diff --git a/.github/workflows/ccpp.yml b/.github/workflows/ccpp.yml
index 7c5811d0..d8af975a 100644
--- a/.github/workflows/ccpp.yml
+++ b/.github/workflows/ccpp.yml
@@ -4,7 +4,7 @@ on: [push]
 
 jobs:
   build-linux:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v1
     - name: apt update
@@ -12,7 +12,7 @@ jobs:
     - name: add-apt-repository
       run: sudo add-apt-repository ppa:vriviere/ppa -y
     - name: apt
-      run: sudo apt install ninja-build lua5.1 pasmo libz80ex-dev flex libbsd-dev libreadline-dev bison binutils-arm-linux-gnueabihf binutils-i686-linux-gnu binutils-powerpc-linux-gnu binutils-m68k-atari-mint binutils-m68k-linux-gnu qemu-user gpp 64tass libfl-dev nasm
+      run: sudo apt install ninja-build lua5.1 libz80ex-dev flex libbsd-dev libreadline-dev bison binutils-arm-linux-gnueabihf binutils-i686-linux-gnu binutils-powerpc-linux-gnu binutils-m68k-atari-mint binutils-m68k-linux-gnu qemu-user gpp 64tass libfl-dev nasm
     - name: make
       run: make NINJAFLAGS=-k1
 
diff --git a/Makefile b/Makefile
index 3b604023..8df12cec 100644
--- a/Makefile
+++ b/Makefile
@@ -1,20 +1,37 @@
 export OBJ = .obj
 export LUA = lua
+export CC = gcc
+export CXX = g++
+export AR = ar
 export CFLAGS = -g -O0
 export LDFLAGS = -g
 export NINJAFLAGS =
 
-all: $(OBJ)/build.ninja
-	@ninja -f $(OBJ)/build.ninja $(NINJAFLAGS)
+export PYTHONHASHSEED = 1
+
+#all: $(OBJ)/build.mk
+#	@+make -f $(OBJ)/build.mk +all
 
+all: $(OBJ)/build.ninja
+	@ninja -f $< +all
+	
 clean:
 	@echo CLEAN
 	@rm -rf $(OBJ) bin
 
-lua-files = $(shell find . -name 'build*.lua') $(wildcard build/*.lua) toolchains.lua
-$(OBJ)/build.ninja: mkninja.lua Makefile $(lua-files)
-	@echo MKNINJA
+build-files = $(shell find . -name 'build.py') build/*.py config.py
+$(OBJ)/build.mk: Makefile $(build-files)
+	@echo ACKBUILDER
 	@mkdir -p $(OBJ)
-	@$(LUA) \
-		mkninja.lua \
-		> $@
+	@python3 -X pycache_prefix=$(OBJ) build/ab2.py -m make -t +all -o $@ build.py
+
+$(OBJ)/build.ninja: Makefile $(build-files)
+	@echo ACKBUILDER
+	@mkdir -p $(OBJ)
+	@python3 -X pycache_prefix=$(OBJ) build/ab2.py -m ninja -t +all -o $@ \
+		-v OBJ,CC,CXX,AR \
+		build.py
+
+.DELETE_ON_ERROR:
+.SECONDARY:
+
diff --git a/bootstrap/build.lua b/bootstrap/build.lua
deleted file mode 100644
index 76a60550..00000000
--- a/bootstrap/build.lua
+++ /dev/null
@@ -1,20 +0,0 @@
-buildcgen {
-	ins = { "bootstrap/cowfe-cgen.bootstrap.c" },
-	outs = { "bin/cowfe-cgen.bootstrap.exe" }
-}
-
-buildcgen {
-	ins = { "bootstrap/cowbe-cgen.bootstrap.c" },
-	outs = { "bin/cowbe-cgen.bootstrap.exe" }
-}
-
-buildcgen {
-	ins = { "bootstrap/cowlink-cgen.bootstrap.c" },
-	outs = { "bin/cowlink-cgen.bootstrap.exe" }
-}
-
-buildcgen {
-	ins = { "bootstrap/cowwrap.bootstrap.c" },
-	outs = { "bin/cowwrap.bootstrap.exe" }
-}
-
diff --git a/bootstrap/build.py b/bootstrap/build.py
new file mode 100644
index 00000000..4a6ddf6e
--- /dev/null
+++ b/bootstrap/build.py
@@ -0,0 +1,6 @@
+from src.toolchains import cgen
+
+cgen(name="cowfe", srcs=["./cowfe-cgen.bootstrap.c"])
+cgen(name="cowbe", srcs=["./cowbe-cgen.bootstrap.c"])
+cgen(name="cowlink", srcs=["./cowlink-cgen.bootstrap.c"])
+cgen(name="cowwrap", srcs=["./cowwrap.bootstrap.c"])
diff --git a/build.py b/build.py
new file mode 100644
index 00000000..97c21ea4
--- /dev/null
+++ b/build.py
@@ -0,0 +1,38 @@
+from build.ab2 import Rule, export
+from os.path import *
+import config
+
+export(
+    name="all",
+    items={
+        "bin/tubeemu": "tools/tubeemu",
+        "bin/obpemu": "tools/obpemu",
+        "bin/mkadfs": "tools+mkadfs",
+        "bin/mkdfs": "tools+mkdfs",
+        "bin/apout": "third_party/apout",
+        "bin/emu2": "third_party/emu2",
+        "bin/zmac": "third_party/zmac",
+        "bin/cpmemu": "tools/cpmemu",
+        "bin/ataritosemu": "tools/ataritosemu",
+        "bin/lx68kemu": "tools/lx68kemu",
+        "bin/fuzix6303emu": "tools/fuzix6303emu",
+        "bin/cowdis-tlcs90": "src/cowdis+cowdis-for-tlcs90-with-nncgen",
+        "bin/cowbdmp": "src/cowbdmp+cowbdmp-with-nncgen",
+        "bin/basicify": "src/misc+basicify-with-nncgen",
+    },
+    deps=[
+        "dist/cpm",
+        "dist/cpmz",
+        "examples",
+        "src/cowasm",
+        "src/cowbe",
+        "src/cowfe",
+        "src/cowlink",
+        "src/cowwrap",
+        "tests",
+        "third_party/djlink+djlink-programs",
+    ]
+    + (["dist/msdos"] if config.has_msdos else [])
+    + (["dist/ataritos"] if config.has_ataritos else [])
+    + (["dist/bbct"] if config.has_bbct else []),
+)
diff --git a/build/ab2.py b/build/ab2.py
new file mode 100644
index 00000000..ab164ee4
--- /dev/null
+++ b/build/ab2.py
@@ -0,0 +1,556 @@
+from collections.abc import Iterable, Sequence
+from os.path import *
+from types import SimpleNamespace
+import argparse
+import copy
+import functools
+import importlib
+import importlib.abc
+import importlib.util
+import inspect
+import re
+import sys
+import types
+import pathlib
+import builtins
+import os
+
+defaultGlobals = {}
+targets = {}
+unmaterialisedTargets = set()
+materialisingStack = []
+outputFp = None
+emitter = None
+currentVars = None
+cwdStack = [""]
+
+sys.path += ["."]
+old_import = builtins.__import__
+
+
+def new_import(name, *args, **kwargs):
+    if name not in sys.modules:
+        path = name.replace(".", "/") + ".py"
+        if isfile(path):
+            sys.stderr.write(f"loading {path}\n")
+            loader = importlib.machinery.SourceFileLoader(name, path)
+
+            spec = importlib.util.spec_from_loader(
+                name, loader, origin="built-in"
+            )
+            module = importlib.util.module_from_spec(spec)
+            sys.modules[name] = module
+            cwdStack.append(dirname(path))
+            spec.loader.exec_module(module)
+            cwdStack.pop()
+
+    return old_import(name, *args, **kwargs)
+
+
+builtins.__import__ = new_import
+
+
+class ABException(BaseException):
+    pass
+
+
+class ParameterList(Sequence):
+    def __init__(self, parent=[]):
+        self.data = parent
+
+    def __getitem__(self, i):
+        return self.data[i]
+
+    def __len__(self):
+        return len(self.data)
+
+    def __str__(self):
+        return " ".join(self.data)
+
+    def __add__(self, other):
+        newdata = self.data.copy() + other
+        return ParameterList(newdata)
+
+    def __repr__(self):
+        return f"<PList: {self.data}>"
+
+
+def Vars(parent=None):
+    data = {}
+
+    class VarsImpl:
+        def __setattr__(self, k, v):
+            data[k] = v
+
+        def __getattr__(self, k):
+            if k in data:
+                return data[k]
+            if parent:
+                return getattr(parent, k)
+            return ParameterList()
+
+        def __repr__(self):
+            return f"<Vars-{id(self)}: {data} -> {parent}>"
+
+        __setitem__ = __setattr__
+        __getitem__ = __getattr__
+
+    return VarsImpl()
+
+
+class Invocation:
+    name = None
+    callback = None
+    types = None
+    ins = None
+    outs = None
+    binding = None
+    vars = None
+    varsettings = None
+
+    def materialise(self, replacing=False):
+        if self in unmaterialisedTargets:
+            if not replacing and (self in materialisingStack):
+                print("Found dependency cycle:")
+                for i in materialisingStack:
+                    print(f"  {i.name}")
+                print(f"  {self.name}")
+                sys.exit(1)
+
+            materialisingStack.append(self)
+
+            # Perform type conversion to the declared rule parameter types.
+
+            self.args = {}
+            for k, v in self.binding.arguments.items():
+                t = self.types.get(k, None)
+                if t:
+                    v = t(v).convert(self)
+                self.args[k] = v
+
+            # Create a new variable frame and set any variables.
+
+            global currentVars
+            self.vars = Vars(self.callerVars)
+            oldVars = currentVars
+            currentVars = self.vars
+
+            if self.varsettings:
+                for k, v in self.varsettings.items():
+                    if k.startswith("+"):
+                        k = k[1:]
+                        self.vars[k] = self.vars[k] + flatten(v)
+                    else:
+                        self.vars[k] = ParameterList(v)
+
+            # Actually call the callback.
+
+            try:
+                cwdStack.append(self.cwd)
+                self.callback(**self.args)
+                cwdStack.pop()
+            except BaseException as e:
+                print(
+                    f"Error materialising {self} ({id(self)}): {self.callback}"
+                )
+                print(f"Arguments: {self.args}")
+                raise e
+            if not self.outs:
+                raise ABException(f"{self.name} didn't set self.outs")
+
+            # Destack the variable and invocation frame.
+
+            currentVars = oldVars
+            if self in unmaterialisedTargets:
+                unmaterialisedTargets.remove(self)
+
+            materialisingStack.pop()
+
+    def __repr__(self):
+        return "<Invocation %s>" % self.name
+
+
+def Rule(func):
+    sig = inspect.signature(func)
+
+    @functools.wraps(func)
+    def wrapper(*, name=None, replaces=None, **kwargs):
+        cwd = None
+        if name:
+            if ("+" in name) and not name.startswith("+"):
+                (cwd, _) = name.split("+", 1)
+        if not cwd:
+            cwd = cwdStack[-1]
+
+        if name:
+            i = Invocation()
+            if name.startswith("./"):
+                name = join(cwd, name)
+            elif "+" not in name:
+                name = cwd + "+" + name
+
+            i.name = name
+            i.localname = name.split("+")[-1]
+
+            if name in targets:
+                raise ABException(f"target {i.name} has already been defined")
+            targets[name] = i
+        elif replaces:
+            i = replaces
+            name = i.name
+        else:
+            raise ABException("you must supply either name or replaces")
+
+        i.cwd = cwd
+        i.types = func.__annotations__
+        i.callback = func
+        i.callerVars = currentVars
+        i.varsettings = kwargs.get("vars", None)
+        setattr(i, func.__name__, SimpleNamespace())
+
+        kwargs.pop("vars", None)
+
+        i.binding = sig.bind(name=name, self=i, **kwargs)
+        i.binding.apply_defaults()
+
+        unmaterialisedTargets.add(i)
+        if replaces:
+            i.materialise(replacing=True)
+        return i
+
+    defaultGlobals[func.__name__] = wrapper
+    return wrapper
+
+
+class Type:
+    def __init__(self, value):
+        self.value = value
+
+
+class Targets(Type):
+    def convert(self, invocation):
+        value = self.value
+        if type(value) is str:
+            value = [value]
+        if type(value) is list:
+            value = targetsof(value, cwd=invocation.cwd)
+        return value
+
+
+class Target(Type):
+    def convert(self, invocation):
+        value = self.value
+        if not value:
+            return None
+        return targetof(value, cwd=invocation.cwd)
+
+
+class TargetsMap(Type):
+    def convert(self, invocation):
+        value = self.value
+        if type(value) is dict:
+            return {
+                targetof(k, cwd=invocation.cwd): targetof(v, cwd=invocation.cwd)
+                for k, v in value.items()
+            }
+        raise ABException(f"wanted a dict of targets, got a {type(value)}")
+
+
+def flatten(*xs):
+    def recurse(xs):
+        for x in xs:
+            if isinstance(x, Iterable) and not isinstance(x, (str, bytes)):
+                yield from recurse(x)
+            else:
+                yield x
+
+    return list(recurse(xs))
+
+
+def fileinvocation(s):
+    i = Invocation()
+    i.name = "(anonymous)"
+    i.outs = [s]
+    targets[s] = i
+    return i
+
+
+def targetof(s, cwd):
+    if isinstance(s, Invocation):
+        s.materialise()
+        return s
+
+    if s in targets:
+        t = targets[s]
+        t.materialise()
+        return t
+
+    if s.startswith("+"):
+        s = cwd + s
+    if s.startswith("./"):
+        s = join(cwd, s)
+    if s.startswith("$"):
+        return fileinvocation(s)
+
+    if "+" not in s:
+        if isdir(s):
+            s = s + "+" + basename(s)
+        else:
+            return fileinvocation(s)
+
+    (path, target) = s.split("+", 2)
+    loadbuildfile(join(path, "build.py"))
+    if not s in targets:
+        raise ABException(f"build file at {path} doesn't contain +{target}")
+    i = targets[s]
+    i.materialise()
+    return i
+
+
+def targetsof(*xs, cwd):
+    return flatten([targetof(x, cwd) for x in flatten(xs)])
+
+
+def filenamesof(*xs):
+    fs = []
+    for t in flatten(xs):
+        if type(t) == str:
+            fs += [t]
+        else:
+            fs += [normpath(f) for f in t.outs]
+    return fs
+
+
+def targetnamesof(*xs):
+    return [x.name for x in flatten(xs)]
+
+
+def filenameof(x):
+    xs = filenamesof(x)
+    if len(xs) != 1:
+        raise ABException("expected a single item")
+    return xs[0]
+
+
+def stripext(path):
+    return splitext(path)[0]
+
+
+def emit(*args):
+    outputFp.write(" ".join(flatten(args)))
+    outputFp.write("\n")
+
+
+def templateexpand(s, invocation):
+    class Converter:
+        def __getitem__(self, key):
+            if key == "vars":
+                return invocation.vars
+            f = filenamesof(invocation.args[key])
+            if isinstance(f, Sequence):
+                f = ParameterList(f)
+            return f
+
+    return eval("f%r" % s, invocation.callback.__globals__, Converter())
+
+
+class MakeEmitter:
+    def begin(self):
+        emit("hide = @")
+        emit(".DELETE_ON_ERROR:")
+        emit(".SECONDARY:")
+
+    def end(self):
+        pass
+
+    def var(self, name, value):
+        # Don't let emit insert spaces.
+        emit(name + "=" + value)
+
+    def rule(self, name, ins, outs, deps=[]):
+        ins = filenamesof(ins)
+        if outs:
+            outs = filenamesof(outs)
+            emit(".PHONY:", name)
+            emit(name, ":", outs, deps)
+            emit(outs, "&:", ins, deps)
+        else:
+            emit(name, ":", ins, deps)
+
+    def label(self, s):
+        emit("\t$(hide)echo", s)
+
+    def exec(self, cs):
+        for c in cs:
+            emit("\t$(hide)", c)
+
+
+def unmake(*ss):
+    return [
+        re.sub(r"\$\(([^)]*)\)", r"$\1", s) for s in flatten(filenamesof(ss))
+    ]
+
+
+class NinjaEmitter:
+    def begin(self):
+        emit("rule build")
+        emit(" command = $command")
+
+    def end(self):
+        pass
+
+    def var(self, name, value):
+        # Don't let emit insert spaces.
+        emit(name + "=" + unmake(value)[0])
+
+    def rule(self, name, ins, outs, deps=[]):
+        if outs:
+            emit("build", name, ": phony", unmake(outs, deps))
+            emit("build", unmake(outs), ": build", unmake(ins))
+        else:
+            emit("build", name, ": phony", unmake(ins, deps))
+
+    def label(self, s):
+        emit(" description=", s)
+
+    def exec(self, cs):
+        emit(" command=", " && ".join(unmake(cs)))
+
+
+@Rule
+def simplerule(
+    self,
+    name,
+    ins: Targets = [],
+    outs=[],
+    deps: Targets = [],
+    commands=[],
+    label="RULE",
+):
+    self.ins = ins
+    self.outs = outs
+    emitter.rule(self.name, filenamesof(ins, deps), outs)
+    emitter.label(templateexpand("{label} {name}", self))
+    cs = []
+
+    for out in filenamesof(outs):
+        dir = dirname(out)
+        if dir:
+            cs += ["mkdir -p " + dir]
+
+    for c in commands:
+        cs += [templateexpand(c, self)]
+    emitter.exec(cs)
+
+
+@Rule
+def normalrule(
+    self,
+    name=None,
+    ins: Targets = [],
+    deps: Targets = [],
+    outs=[],
+    label="RULE",
+    objdir=None,
+    commands=[],
+):
+    objdir = objdir or join("$(OBJ)", name)
+
+    simplerule(
+        replaces=self,
+        ins=ins,
+        deps=deps,
+        outs=[join(objdir, f) for f in outs],
+        label=label,
+        commands=commands,
+    )
+
+
+@Rule
+def export(self, name=None, items: TargetsMap = {}, deps: Targets = []):
+    emitter.rule(
+        self.name,
+        flatten(items.values()),
+        filenamesof(items.keys()),
+        filenamesof(deps),
+    )
+    emitter.label(f"EXPORT {self.name}")
+
+    cs = []
+    self.ins = items.values()
+    self.outs = filenamesof(deps)
+    for dest, src in items.items():
+        destf = filenameof(dest)
+        dir = dirname(destf)
+        if dir:
+            cs += ["mkdir -p " + dir]
+
+        srcs = filenamesof(src)
+        if len(srcs) != 1:
+            raise ABException(
+                "a dependency of an export must have exactly one output file"
+            )
+
+        cs += ["cp %s %s" % (srcs[0], destf)]
+        self.outs += [destf]
+
+    emitter.exec(cs)
+
+
+def loadbuildfile(filename):
+    filename = filename.replace("/", ".").removesuffix(".py")
+    builtins.__import__(filename)
+
+
+def load(filename):
+    loadbuildfile(filename)
+    callerglobals = inspect.stack()[1][0].f_globals
+    for k, v in defaultGlobals.items():
+        callerglobals[k] = v
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "-m", "--mode", choices=["make", "ninja"], default="make"
+    )
+    parser.add_argument("-o", "--output")
+    parser.add_argument("files", nargs="+")
+    parser.add_argument("-t", "--targets", action="append")
+    parser.add_argument("-v", "--vars", action="append")
+    args = parser.parse_args()
+
+    global outputFp
+    outputFp = open(args.output, "wt")
+
+    global emitter
+    if args.mode == "make":
+        emitter = MakeEmitter()
+    else:
+        emitter = NinjaEmitter()
+    emitter.begin()
+
+    for v in flatten([a.split(",") for a in args.vars]):
+        e = os.getenv(v)
+        if e:
+            emitter.var(v, e)
+
+    global currentVars
+    currentVars = Vars()
+
+    for k in ("Rule", "Targets", "load", "filenamesof", "stripext"):
+        defaultGlobals[k] = globals()[k]
+
+    global __name__
+    sys.modules["build.ab2"] = sys.modules[__name__]
+    __name__ = "build.ab2"
+
+    for f in args.files:
+        loadbuildfile(f)
+
+    for t in flatten([a.split(",") for a in args.targets]):
+        targets[t].materialise()
+    emitter.end()
+
+
+main()
diff --git a/build/c.lua b/build/c.lua
deleted file mode 100644
index 77d63569..00000000
--- a/build/c.lua
+++ /dev/null
@@ -1,138 +0,0 @@
-function cfile(e)
-	local hdrs = {}
-	for _, src in ipairs(e.ins) do
-		local f = src:gsub("[^/]*$", "")
-		if f == "" then
-			f = "."
-		end
-		hdrs[#hdrs+1] = "-I"..f
-	end
-
-	local cflags = e.cflags or ""
-	rule {
-		ins = e.ins,
-		outs = e.outs,
-		cmd = "$CC $CFLAGS "..cflags.." "..joined(hdrs).." -c -o &1 @1"
-	}
-end
-
-function cprogram(e)
-	local objdir = e.objdir or "$OBJ"
-	local objs = {}
-	local hdrs = {}
-	local libs = {}
-	for _, src in ipairs(e.ins) do
-		if src:find("%.h$") then
-			hdrs[#hdrs+1] = src
-		end
-	end
-
-	for _, src in ipairs(e.ins) do
-		if src:find("%.a$") then
-			libs[#libs+1] = src
-		elseif not src:find("%.h$") then
-			local o = objdir.."/"..src:gsub("%.c$", ".o"):gsub("%.cpp$", ".o")
-			objs[#objs+1] = o
-			cfile {
-				ins = concat {
-					src,
-					hdrs
-				},
-				outs = { o },
-				cflags = e.cflags,
-			}
-		end
-	end
-
-	local ldflags = e.ldflags or ""
-	rule {
-		ins = concat { objs, libs },
-		outs = e.outs,
-		cmd = "$CC -o &1 @@ "..joined(libs).." $LDFLAGS "..ldflags
-	}
-end
-
-function clibrary(e)
-	local objdir = e.objdir or "$OBJ"
-	local objs = {}
-	local hdrs = {}
-	for _, src in ipairs(e.ins) do
-		if src:find("%.h$") then
-			hdrs[#hdrs+1] = src
-		end
-	end
-
-	for _, src in ipairs(e.ins) do
-		if not src:find("%.h$") then
-			local o = objdir.."/"..src:gsub("%.c$", ".o"):gsub("%.cpp$", ".o")
-			objs[#objs+1] = o
-			cfile {
-				ins = concat {
-					src,
-					hdrs
-				},
-				outs = { o },
-				cflags = e.cflags,
-			}
-		end
-	end
-
-	rule {
-		ins = objs,
-		outs = e.outs,
-		cmd = "rm -f &1 && $AR qcs &1 @@"
-	}
-end
-
-function cxxfile(e)
-	local hdrs = {}
-	for _, src in ipairs(e.ins) do
-		local f = src:gsub("[^/]*$", "")
-		if f == "" then
-			f = "."
-		end
-		hdrs[#hdrs+1] = "-I"..f
-	end
-
-	local cxxflags = e.cxxflags or ""
-	rule {
-		ins = e.ins,
-		outs = e.outs,
-		cmd = "$CXX $CXXFLAGS "..cxxflags.." "..joined(hdrs).." -c -o &1 @1"
-	}
-end
-
-function cxxprogram(e)
-	local objdir = e.objdir or "$OBJ"
-	local objs = {}
-	local hdrs = {}
-	for _, src in ipairs(e.ins) do
-		if src:find("%.h$") then
-			hdrs[#hdrs+1] = src
-		end
-	end
-
-	for _, src in ipairs(e.ins) do
-		if not src:find("%.h$") then
-			local o = objdir.."/"..src:gsub("%.cc$", ".o"):gsub("%.cpp$", ".o")
-			objs[#objs+1] = o
-			cxxfile {
-				ins = concat {
-					src,
-					hdrs
-				},
-				outs = { o },
-				cxxflags = e.cxxflags,
-			}
-		end
-	end
-
-	local ldflags = e.ldflags or ""
-	rule {
-		ins = objs,
-		outs = e.outs,
-		cmd = "$CXX -o &1 @@ $LDFLAGS "..ldflags
-	}
-end
-
-
diff --git a/build/c.py b/build/c.py
new file mode 100644
index 00000000..6ce13890
--- /dev/null
+++ b/build/c.py
@@ -0,0 +1,152 @@
+from build.ab2 import (
+    Rule,
+    Targets,
+    normalrule,
+    filenamesof,
+    filenameof,
+    stripext,
+    flatten,
+)
+from os.path import *
+
+
+def cfileimpl(self, name, srcs, deps, suffix, commands, label, kind, flags):
+    if not name:
+        name = filenamesof(srcs)[1]
+
+    dirs = []
+    for d in deps:
+        for f in filenamesof(d):
+            if f.endswith(".h"):
+                dirs += [dirname(f)]
+        try:
+            dirs += d.clibrary.dirs
+        except:
+            pass
+
+    includeflags = set(["-I" + f for f in filenamesof(dirs)])
+
+    outleaf = stripext(basename(name)) + suffix
+
+    normalrule(
+        replaces=self,
+        ins=srcs,
+        deps=deps,
+        outs=[outleaf],
+        label=label,
+        commands=commands,
+        vars={"+" + flags: flatten(includeflags)},
+    )
+
+
+@Rule
+def cfile(
+    self,
+    name,
+    srcs: Targets = [],
+    deps: Targets = [],
+    suffix=".o",
+    commands=["$(CC) -c -o {outs[0]} {ins[0]} {vars.cflags}"],
+    label="CC",
+):
+    cfileimpl(
+        self, name, srcs, deps, suffix, commands, label, "cfile", "cflags"
+    )
+
+
+@Rule
+def cxxfile(
+    self,
+    name,
+    srcs: Targets = [],
+    deps: Targets = [],
+    suffix=".o",
+    commands=["$(CXX) -c -o {outs[0]} {ins[0]} {vars.cxxflags}"],
+    label="CXX",
+):
+    cfileimpl(
+        self, name, srcs, deps, suffix, commands, label, "cxxfile", "cxxflags"
+    )
+
+
+def findsources(name, srcs, deps):
+    ins = []
+    for f in filenamesof(srcs):
+        if f.endswith(".c") or f.endswith(".cc") or f.endswith(".cpp"):
+            ins += [
+                cfile(
+                    name=name + "/" + basename(filenamesof(f)[0]),
+                    srcs=[f],
+                    deps=deps,
+                )
+            ]
+    return ins
+
+
+@Rule
+def clibrary(
+    self,
+    name,
+    srcs: Targets = [],
+    deps: Targets = [],
+    hdrs: Targets = [],
+    commands=["$(AR) cqs {outs[0]} {ins}"],
+    label="AR",
+):
+    for f in filenamesof(srcs):
+        if f.endswith(".h"):
+            deps += [f]
+
+    normalrule(
+        replaces=self,
+        ins=findsources(name, srcs, deps),
+        outs=[basename(name) + ".a"],
+        label=label,
+        commands=commands,
+    )
+
+    dirs = set([dirname(f) for f in filenamesof(hdrs)])
+
+    self.clibrary.hdrs = hdrs
+    self.clibrary.dirs = dirs
+
+
+def programimpl(self, name, srcs, deps, commands, label, filerule, kind):
+    libraries = [d.outs for d in deps if hasattr(d, "clibrary")]
+
+    for f in filenamesof(srcs):
+        if f.endswith(".h"):
+            deps += [f]
+
+    normalrule(
+        replaces=self,
+        ins=findsources(name, srcs, deps),
+        outs=[basename(name)],
+        label=label,
+        commands=commands,
+        vars={"+ldflags": libraries},
+    )
+
+
+@Rule
+def cprogram(
+    self,
+    name,
+    srcs: Targets = [],
+    deps: Targets = [],
+    commands=["$(CC) -o {outs[0]} {ins} {vars.ldflags}"],
+    label="CLINK",
+):
+    programimpl(self, name, srcs, deps, commands, label, cfile, "cprogram")
+
+
+@Rule
+def cxxprogram(
+    self,
+    name,
+    srcs: Targets = [],
+    deps: Targets = [],
+    commands=["$(CXX) -o {outs[0]} {ins} {vars.ldflags}"],
+    label="CXXLINK",
+):
+    programimpl(self, name, srcs, deps, commands, label, cxxfile, "cxxprogram")
diff --git a/build/gpp.lua b/build/gpp.lua
deleted file mode 100644
index e74ca2f3..00000000
--- a/build/gpp.lua
+++ /dev/null
@@ -1,20 +0,0 @@
-function gpp(e)
-	local hdrs = {}
-	for _, src in ipairs(e.ins) do
-		local f = src:gsub("[^/]*$", "")
-		if f == "" then
-			f = "."
-		end
-		hdrs[#hdrs+1] = "-I"..f
-	end
-
-	local cflags = e.cflags or ""
-	rule {
-		ins = e.ins,
-		outs = e.outs,
-		cmd = "gpp --nostdinc -U '' '' '(' ',' ')' '(' ')' '$$' '' -M '$$' '\\n' ' ' ' ' '\\n' '(' ')' "..
-			cflags.." "..joined(hdrs).." -o &1 @1"
-	}
-end
-
-
diff --git a/build/gpp.py b/build/gpp.py
new file mode 100644
index 00000000..4c87b5eb
--- /dev/null
+++ b/build/gpp.py
@@ -0,0 +1,18 @@
+from build.ab2 import Rule, normalrule, Targets, filenamesof
+from os.path import *
+
+
+@Rule
+def gpp(self, name, srcs: Targets = []):
+    hdrs = set(["-I" + dirname(f) for f in filenamesof(srcs)])
+
+    normalrule(
+        replaces=self,
+        ins=srcs,
+        outs=[self.localname + ".i"],
+        commands=[
+            "gpp --nostdinc -U '' '' '(' ',' ')' '(' ')' '$$' '' -M '$$' '\\n' ' ' ' ' '\\n' '(' ')' "
+            + (" ".join(hdrs))
+            + " -o {outs} {ins[0]}"
+        ],
+    )
diff --git a/build/nasm.py b/build/nasm.py
new file mode 100644
index 00000000..74174ed1
--- /dev/null
+++ b/build/nasm.py
@@ -0,0 +1,12 @@
+from build.ab2 import normalrule, Rule, Targets, filenameof
+
+
+@Rule
+def nasm(self, name, srcs: Targets = []):
+    normalrule(
+        replaces=self,
+        ins=srcs,
+        outs=[self.localname + ".obj"],
+        commands=["nasm -f obj -o {outs} {ins}"],
+        label="NASM",
+    )
diff --git a/build/tass64.lua b/build/tass64.lua
deleted file mode 100644
index 4a18f328..00000000
--- a/build/tass64.lua
+++ /dev/null
@@ -1,20 +0,0 @@
-function tass64(e)
-	local hdrs = {}
-	for _, src in ipairs(e.ins) do
-		local f = src:gsub("[^/]*$", "")
-		if f == "" then
-			f = "."
-		end
-		hdrs[#hdrs+1] = "-I"..f
-	end
-
-	local cflags = e.cflags or ""
-	rule {
-		ins = e.ins,
-		outs = e.outs,
-		cmd = "64tass --quiet --long-branch --ascii --case-sensitive --nostart -o &1 @1"
-	}
-end
-
-
-
diff --git a/build/tass64.py b/build/tass64.py
new file mode 100644
index 00000000..28ae843f
--- /dev/null
+++ b/build/tass64.py
@@ -0,0 +1,14 @@
+from build.ab2 import normalrule, Rule, Targets, filenameof
+
+
+@Rule
+def tass64(self, name, srcs: Targets = []):
+    normalrule(
+        replaces=self,
+        ins=srcs,
+        outs=[self.localname + ".bin"],
+        commands=[
+            "64tass --quiet --long-branch --ascii --case-sensitive --nostart -o {outs} {ins}"
+        ],
+        label="TASS64",
+    )
diff --git a/build/utils.lua b/build/utils.lua
deleted file mode 100644
index 7667f059..00000000
--- a/build/utils.lua
+++ /dev/null
@@ -1,9 +0,0 @@
-function copy(e)
-	rule {
-		ins = e.ins,
-		outs = e.outs,
-		cmd = "cp @1 &1"
-	}
-end
-
-
diff --git a/build/yacc.lua b/build/yacc.lua
deleted file mode 100644
index d1e18f38..00000000
--- a/build/yacc.lua
+++ /dev/null
@@ -1,16 +0,0 @@
-function yacc(e)
-	rule {
-		ins = e.ins,
-		outs = e.outs,
-		cmd = "bison -y -t -o &1 --defines=&2 @1"
-	}
-end
-
-function flex(e)
-	rule {
-		ins = e.ins,
-		outs = e.outs,
-		cmd = "flex -8 -Cem -s -t @1 > &1"
-	}
-end
-
diff --git a/build/yacc.py b/build/yacc.py
new file mode 100644
index 00000000..39481c54
--- /dev/null
+++ b/build/yacc.py
@@ -0,0 +1,23 @@
+from build.ab2 import normalrule, Rule, Targets
+
+
+@Rule
+def yacc(self, name, srcs: Targets = []):
+    normalrule(
+        replaces=self,
+        ins=srcs,
+        outs=["y.tab.c", "y.tab.h"],
+        commands=["bison -y -t -o {outs[0]} --defines={outs[1]} {ins}"],
+        label="YACC",
+    )
+
+
+@Rule
+def flex(self, name, srcs: Targets = []):
+    normalrule(
+        replaces=self,
+        ins=srcs,
+        outs=["lexer.c"],
+        commands=["flex -8 -Cem -s -t {ins[0]} > {outs[0]}"],
+        label="FLEX",
+    )
diff --git a/config.py b/config.py
new file mode 100644
index 00000000..e3ed5441
--- /dev/null
+++ b/config.py
@@ -0,0 +1,28 @@
+import os
+
+
+def enable_if(command):
+    return os.system(f"command -v {command} > /dev/null") == 0
+
+
+has_gccataritos = enable_if("m68k-atari-mint-as")
+has_nasm = enable_if("nasm")
+has_gcc386 = enable_if("i686-linux-gnu-as")
+has_gcc68k = enable_if("m68k-linux-gnu-as")
+has_gccthumb2 = enable_if("arm-linux-gnueabihf-as")
+has_gccpowerpc = enable_if("powerpc-linux-gnu-as")
+has_tass64 = enable_if("64tass")
+has_qemuarm = enable_if("qemu-arm")
+has_qemu386 = enable_if("qemu-i386")
+has_qemuppc = enable_if("qemu-ppc")
+has_qemu68k = enable_if("qemu-m68k")
+
+has_ataritos = has_gccataritos
+has_msdos = has_nasm
+has_lx386 = has_gcc386
+has_lxthumb2 = has_gccthumb2
+has_lx68k = has_gcc68k
+has_lxppc = has_gccpowerpc
+has_bbct = has_tass64
+has_bbctiny = has_tass64
+has_bbct6502 = has_tass64
diff --git a/dist/ataritos/build.lua b/dist/ataritos/build.lua
deleted file mode 100644
index 81ed918d..00000000
--- a/dist/ataritos/build.lua
+++ /dev/null
@@ -1,37 +0,0 @@
-if WITH_ATARITOS then
-	copy {
-		ins = { "examples/mandel.cow" },
-		outs = { "$OBJ/dist/ataritos/mandel.cow" },
-	}
-
-	copy {
-		ins = { "rt/ataritos/cowgol.coh" },
-		outs = { "$OBJ/dist/ataritos/cowgol.coh" },
-	}
-
-	copy {
-		ins = { "rt/common.coh" },
-		outs = { "$OBJ/dist/ataritos/common.coh" },
-	}
-
-	copy {
-		ins = { "$OBJ/rt/ataritos/cowgol.coo" },
-		outs = { "$OBJ/dist/ataritos/cowgol.coo" }
-	}
-
-	copy {
-		ins = { "bin/cowfe-32bita2.ataritos.ataritos.tos" },
-		outs = { "$OBJ/dist/ataritos/cowfe.tos" }
-	}
-
-	copy {
-		ins = { "bin/cowbe-68000.ataritos.ataritos.tos" },
-		outs = { "$OBJ/dist/ataritos/cowbe.tos" }
-	}
-
-	copy {
-		ins = { "bin/cowlink-ataritos.ataritos.ataritos.tos" },
-		outs = { "$OBJ/dist/ataritos/cowlink.tos" }
-	}
-end
-
diff --git a/dist/ataritos/build.py b/dist/ataritos/build.py
new file mode 100644
index 00000000..8f5edcb6
--- /dev/null
+++ b/dist/ataritos/build.py
@@ -0,0 +1,17 @@
+from build.ab2 import export
+from tools.build import tocpm
+
+tocpm(name="demosub", src="./demo.sub")
+
+export(
+    name="ataritos",
+    items={
+        "bin/dist/ataritos/mandel.cow": "examples/mandel.cow",
+        "bin/dist/ataritos/cowgol.coh": "rt/ataritos/cowgol.coh",
+        "bin/dist/ataritos/common.coh": "rt/common.coh",
+        "bin/dist/ataritos/cowgol.coo": "rt/ataritos+cowgolcoo",
+        "bin/dist/ataritos/cowfe.com": "src/cowfe+cowfe-for-32bita2-with-ataritos",
+        "bin/dist/ataritos/cowbe.com": "src/cowbe+cowbe-for-68000-with-ataritos",
+        "bin/dist/ataritos/cowlink.com": "src/cowlink+cowlink-for-ataritos-with-ataritos",
+    },
+)
diff --git a/dist/bbct/build.lua b/dist/bbct/build.lua
deleted file mode 100644
index f7b5cb5c..00000000
--- a/dist/bbct/build.lua
+++ /dev/null
@@ -1,43 +0,0 @@
-function bbcify(e)
-	rule {
-		ins = e.ins,
-		outs = e.outs,
-		cmd = [[sed -e 's/include "\(.*\)\.coh"/include "h.\1"/' < @1 | expand -t4 | tr '\n' '\r' > &1]]
-	}
-end
-
-bbcify {
-	ins = { "examples/mandel.cow" },
-	outs = { "$OBJ/dist/bbct/mandel.cow" },
-}
-
-bbcify {
-	ins = { "rt/bbct/cowgol.coh" },
-	outs = { "$OBJ/dist/bbct/cowgol.coh" },
-}
-
-bbcify {
-	ins = { "rt/common.coh" },
-	outs = { "$OBJ/dist/bbct/common.coh" },
-}
-
-mkdfs {
-	ins = {
-		"-f", "dist/bbct/!boot",
-		"-f", "bin/cowfe-6502.bbct.bbct", "-e0x400", "-l0x400", "-ncowfe",
-		"-f", "bin/cowbe-65c02.bbct.bbct", "-e0x400", "-l0x400", "-ncowbe",
-		"-f", "bin/cowlink-bbctn.bbct.bbct", "-e0x400", "-l0x400", "-ncowlink",
-		"-f", "$OBJ/rt/bbct/cowgol.coo", "-no.cowgol",
-		"-f", "$OBJ/dist/bbct/cowgol.coh", "-nh.cowgol",
-		"-f", "$OBJ/dist/bbct/common.coh", "-nh.common",
-		"-f", "$OBJ/dist/bbct/mandel.cow", "-nw.source",
-		"-B3"
-	},
-	outs = { "bbct.ssd" }
-}
-
-mkdfs {
-	ins = {},
-	outs = { "bbctwork.ssd" }
-}
-
diff --git a/dist/bbct/build.py b/dist/bbct/build.py
new file mode 100644
index 00000000..a650bed3
--- /dev/null
+++ b/dist/bbct/build.py
@@ -0,0 +1,68 @@
+from build.ab2 import export, Rule, Target, normalrule
+from tools.build import tocpm, mkdfs
+
+
+@Rule
+def bbcify(self, name, src: Target = None):
+    normalrule(
+        replaces=self,
+        ins=[src],
+        outs=[self.localname + ".txt"],
+        commands=[
+            r"""sed -e 's/include "\(.*\)\.coh"/include "h.\1"/' < {ins} | expand -t4 | tr '\n' '\r' > {outs}"""
+        ],
+        label="BBCIFY",
+    )
+
+
+bbcify(name="mandelcow", src="examples/mandel.cow")
+bbcify(name="cowgolcoh", src="rt/bbct/cowgol.coh")
+bbcify(name="commoncoh", src="rt/common.coh")
+
+mkdfs(
+    name="ssd",
+    flags=[
+        ["-f", Target("./!boot")],
+        [
+            "-f",
+            Target("src/cowfe+cowfe-for-16bit-with-bbct"),
+            "-e0x400",
+            "-l0x400",
+            "-ncowfe",
+        ],
+        [
+            "-f",
+            Target("src/cowbe+cowbe-for-6502-with-bbct"),
+            "-e0x400",
+            "-l0x400",
+            "-ncowbe",
+        ],
+        [
+            "-f",
+            Target("src/cowlink+cowlink-for-bbct-with-bbct"),
+            "-e0x400",
+            "-l0x400",
+            "-ncowlink",
+        ],
+        ["-f", Target("rt/bbct+cowgolcoo"), "-no.cowgol"],
+        ["-f", Target("+cowgolcoh"), "-nh.cowgol"],
+        ["-f", Target("+commoncoh"), "-nh.common"],
+        ["-f", Target("+mandelcow"), "-nw.source"],
+        "-B3",
+    ],
+)
+
+export(
+    name="bbct",
+    items={
+        "bin/dist/bbct/!boot": "./!boot",
+        "bin/dist/bbct/mandel.cow": "+mandelcow",
+        "bin/dist/bbct/cowgol.coh": "+cowgolcoh",
+        "bin/dist/bbct/common.coh": "+commoncoh",
+        "bin/dist/bbct/cowgol.coo": "rt/bbct+cowgolcoo",
+        "bin/dist/bbct/cowfe.com": "src/cowfe+cowfe-for-16bit-with-bbct",
+        "bin/dist/bbct/cowbe.com": "src/cowbe+cowbe-for-6502-with-bbct",
+        "bin/dist/bbct/cowlink.com": "src/cowlink+cowlink-for-bbct-with-bbct",
+        "bin/dist/bbct.ssd": "+ssd",
+    },
+)
diff --git a/dist/cpm/build.lua b/dist/cpm/build.lua
deleted file mode 100644
index e8cc8c79..00000000
--- a/dist/cpm/build.lua
+++ /dev/null
@@ -1,64 +0,0 @@
-function cpmify(e)
-	rule {
-		ins = concat {
-			"dist/cpm/tocpm.lua",
-			e.ins,
-		},
-		outs = e.outs,
-		cmd = "$LUA @1 < @2 > &1",
-	}
-end
-
-function copy(e)
-	rule {
-		ins = e.ins,
-		outs = e.outs,
-		cmd = "cp @1 &1"
-	}
-end
-
-cpmify {
-	ins = { "examples/mandel.cow" },
-	outs = { "$OBJ/dist/cpm/mandel.cow" },
-}
-
-cpmify {
-	ins = { "rt/cpm/cowgol.coh" },
-	outs = { "$OBJ/dist/cpm/cowgol.coh" },
-}
-
-cpmify {
-	ins = { "rt/common.coh" },
-	outs = { "$OBJ/dist/cpm/common.coh" },
-}
-
-cpmify {
-	ins = { "dist/cpm/demo.sub" },
-	outs = { "$OBJ/dist/cpm/demo.sub" },
-}
-
-copy {
-	ins = { "$OBJ/rt/cpm/cowgol.coo" },
-	outs = { "$OBJ/dist/cpm/cowgol.coo" }
-}
-
-copy {
-	ins = { "bin/cowfe-16bit.ncpm.8080.com" },
-	outs = { "$OBJ/dist/cpm/cowfe.com" }
-}
-
-copy {
-	ins = { "bin/cowbe-8080.ncpm.8080.com" },
-	outs = { "$OBJ/dist/cpm/cowbe.com" }
-}
-
-copy {
-	ins = { "bin/cowlink-8080.ncpm.8080.com" },
-	outs = { "$OBJ/dist/cpm/cowlink.com" }
-}
-
-copy {
-	ins = { "bin/cowasm-8080.ncpm.8080.com" },
-	outs = { "$OBJ/dist/cpm/cowasm.com" }
-}
-
diff --git a/dist/cpm/build.py b/dist/cpm/build.py
new file mode 100644
index 00000000..4112cfdf
--- /dev/null
+++ b/dist/cpm/build.py
@@ -0,0 +1,18 @@
+from build.ab2 import export
+from tools.build import tocpm
+
+tocpm(name="demosub", src="./demo.sub")
+
+export(
+    name="cpm",
+    items={
+        "bin/dist/cpm/demo.sub": "+demosub",
+        "bin/dist/cpm/mandel.cow": "examples/mandel.cow",
+        "bin/dist/cpm/cowgol.coh": "rt/cpm/cowgol.coh",
+        "bin/dist/cpm/common.coh": "rt/common.coh",
+        "bin/dist/cpm/cowgol.coo": "rt/cpm+cowgolcoo",
+        "bin/dist/cpm/cowfe.com": "src/cowfe+cowfe-for-16bit-with-ncpm",
+        "bin/dist/cpm/cowbe.com": "src/cowbe+cowbe-for-8080-with-ncpm",
+        "bin/dist/cpm/cowlink.com": "src/cowlink+cowlink-for-8080-with-ncpm",
+    },
+)
diff --git a/dist/cpmbasic/build.lua b/dist/cpmbasic/build.lua
deleted file mode 100644
index 301b8d21..00000000
--- a/dist/cpmbasic/build.lua
+++ /dev/null
@@ -1,54 +0,0 @@
-function cpmify(e)
-	rule {
-		ins = concat {
-			"dist/cpmbasic/tocpm.lua",
-			e.ins,
-		},
-		outs = e.outs,
-		cmd = "$LUA @1 < @2 > &1",
-	}
-end
-
-function copy(e)
-	rule {
-		ins = e.ins,
-		outs = e.outs,
-		cmd = "cp @1 &1"
-	}
-end
-
-cpmify {
-	ins = { "dist/cpmbasic/demo.sub" },
-	outs = { "$OBJ/dist/cpmbasic/demo.sub" },
-}
-
-cpmify {
-	ins = { "examples/music.dat" },
-	outs = { "$OBJ/dist/cpmbasic/music.dat" },
-}
-
-cpmify {
-	ins = { "examples/crisps.cow" },
-	outs = { "$OBJ/dist/cpmbasic/crisps.cow" },
-}
-
-copy {
-	ins = { "bin/cowfe-basic.ncpmz.z80.com" },
-	outs = { "$OBJ/dist/cpmbasic/cowfe.com" }
-}
-
-copy {
-	ins = { "bin/cowbe-basic.ncpmz.z80.com" },
-	outs = { "$OBJ/dist/cpmbasic/cowbe.com" }
-}
-
-copy {
-	ins = { "bin/cowlink-basic.ncpmz.z80.com" },
-	outs = { "$OBJ/dist/cpmbasic/cowlink.com" }
-}
-
-copy {
-	ins = { "bin/basicify.ncpmz.z80.com" },
-	outs = { "$OBJ/dist/cpmbasic/basicify.com" }
-}
-
diff --git a/dist/cpmbasic/tocpm.lua b/dist/cpmbasic/tocpm.lua
deleted file mode 100644
index 1176c6f2..00000000
--- a/dist/cpmbasic/tocpm.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-for l in io.stdin:lines() do
-	io.write(l, "\r\n")
-end
-io.write(string.char(26))
-
diff --git a/dist/cpmz/build.lua b/dist/cpmz/build.lua
deleted file mode 100644
index 48bdf0e8..00000000
--- a/dist/cpmz/build.lua
+++ /dev/null
@@ -1,59 +0,0 @@
-function cpmify(e)
-	rule {
-		ins = concat {
-			"dist/cpmz/tocpm.lua",
-			e.ins,
-		},
-		outs = e.outs,
-		cmd = "$LUA @1 < @2 > &1",
-	}
-end
-
-function copy(e)
-	rule {
-		ins = e.ins,
-		outs = e.outs,
-		cmd = "cp @1 &1"
-	}
-end
-
-cpmify {
-	ins = { "examples/mandel.cow" },
-	outs = { "$OBJ/dist/cpmz/mandel.cow" },
-}
-
-cpmify {
-	ins = { "rt/cpmz/cowgol.coh" },
-	outs = { "$OBJ/dist/cpmz/cowgol.coh" },
-}
-
-cpmify {
-	ins = { "rt/common.coh" },
-	outs = { "$OBJ/dist/cpmz/common.coh" },
-}
-
-cpmify {
-	ins = { "dist/cpmz/demo.sub" },
-	outs = { "$OBJ/dist/cpmz/demo.sub" },
-}
-
-copy {
-	ins = { "$OBJ/rt/cpmz/cowgol.coo" },
-	outs = { "$OBJ/dist/cpmz/cowgol.coo" }
-}
-
-copy {
-	ins = { "bin/cowfe-16bit.ncpmz.z80.com" },
-	outs = { "$OBJ/dist/cpmz/cowfe.com" }
-}
-
-copy {
-	ins = { "bin/cowbe-z80.ncpmz.z80.com" },
-	outs = { "$OBJ/dist/cpmz/cowbe.com" }
-}
-
-copy {
-	ins = { "bin/cowlink-8080.ncpmz.z80.com" },
-	outs = { "$OBJ/dist/cpmz/cowlink.com" }
-}
-
diff --git a/dist/cpmz/build.py b/dist/cpmz/build.py
new file mode 100644
index 00000000..d03a1a24
--- /dev/null
+++ b/dist/cpmz/build.py
@@ -0,0 +1,18 @@
+from build.ab2 import export
+from tools.build import tocpm
+
+tocpm(name="demosub", src="./demo.sub")
+
+export(
+    name="cpmz",
+    items={
+        "bin/dist/cpmz/demo.sub": "+demosub",
+        "bin/dist/cpmz/mandel.cow": "examples/mandel.cow",
+        "bin/dist/cpmz/cowgol.coh": "rt/cpmz/cowgol.coh",
+        "bin/dist/cpmz/common.coh": "rt/common.coh",
+        "bin/dist/cpmz/cowgol.coo": "rt/cpmz+cowgolcoo",
+        "bin/dist/cpmz/cowfe.com": "src/cowfe+cowfe-for-16bit-with-ncpmz",
+        "bin/dist/cpmz/cowbe.com": "src/cowbe+cowbe-for-z80-with-ncpmz",
+        "bin/dist/cpmz/cowlink.com": "src/cowlink+cowlink-for-8080-with-ncpmz",
+    },
+)
diff --git a/dist/cpmz/tocpm.lua b/dist/cpmz/tocpm.lua
deleted file mode 100644
index 1176c6f2..00000000
--- a/dist/cpmz/tocpm.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-for l in io.stdin:lines() do
-	io.write(l, "\r\n")
-end
-io.write(string.char(26))
-
diff --git a/dist/msdos/build.lua b/dist/msdos/build.lua
deleted file mode 100644
index ba48d407..00000000
--- a/dist/msdos/build.lua
+++ /dev/null
@@ -1,42 +0,0 @@
-if WITH_MSDOS then
-	copy {
-		ins = { "examples/mandel.cow" },
-		outs = { "$OBJ/dist/msdos/mandel.cow" },
-	}
-
-	cpmify {
-		ins = { "rt/msdos/cowgol.coh" },
-		outs = { "$OBJ/dist/msdos/cowgol.coh" },
-	}
-
-	cpmify {
-		ins = { "rt/common.coh" },
-		outs = { "$OBJ/dist/msdos/common.coh" },
-	}
-
-	cpmify {
-		ins = { "dist/msdos/demo.bat" },
-		outs = { "$OBJ/dist/msdos/demo.bat" },
-	}
-
-	copy {
-		ins = { "$OBJ/rt/msdos/cowgol.coo" },
-		outs = { "$OBJ/dist/msdos/cowgol.coo" }
-	}
-
-	copy {
-		ins = { "bin/cowfe-16bit.msdos.msdos.exe" },
-		outs = { "$OBJ/dist/msdos/cowfe.exe" }
-	}
-
-	copy {
-		ins = { "bin/cowbe-8086.msdos.msdos.exe" },
-		outs = { "$OBJ/dist/msdos/cowbe.exe" }
-	}
-
-	copy {
-		ins = { "bin/cowlink-msdos.msdos.msdos.exe" },
-		outs = { "$OBJ/dist/msdos/cowlink.exe" }
-	}
-end
-
diff --git a/dist/msdos/build.py b/dist/msdos/build.py
new file mode 100644
index 00000000..f0ba8c9d
--- /dev/null
+++ b/dist/msdos/build.py
@@ -0,0 +1,15 @@
+from build.ab2 import export
+
+export(
+    name="msdos",
+    items={
+        "bin/dist/msdos/demo.bat": "./demo.bat",
+        "bin/dist/msdos/mandel.cow": "examples/mandel.cow",
+        "bin/dist/msdos/cowgol.coh": "rt/msdos/cowgol.coh",
+        "bin/dist/msdos/common.coh": "rt/common.coh",
+        "bin/dist/msdos/cowgol.coo": "rt/msdos+cowgolcoo",
+        "bin/dist/msdos/cowfe.exe": "src/cowfe+cowfe-for-16bit-with-msdos",
+        "bin/dist/msdos/cowbe.exe": "src/cowbe+cowbe-for-8086-with-msdos",
+        "bin/dist/msdos/cowlink.exe": "src/cowlink+cowlink-for-msdos-with-msdos",
+    },
+)
diff --git a/doc/building.md b/doc/building.md
index f986970a..e282a3fa 100644
--- a/doc/building.md
+++ b/doc/building.md
@@ -9,7 +9,7 @@ dependencies.
 
   - the Ninja build tool
 
-  - Lua 5.1 (needed for the build)
+  - Python 3 and Lua 5.1 (needed for the build)
 
   - the Pasmo Z80 assembler (needed to build part of the CP/M emulator)
 
@@ -37,7 +37,7 @@ dependencies.
 If you're on a Debianish platform, you should be able to install them (after
 adding any custom package sources as above) with:
 
-    apt install ninja-build lua5.1 pasmo libz80ex-dev flex libbsd-dev libreadline-dev bison binutils-arm-linux-gnueabihf binutils-i686-linux-gnu binutils-powerpc-linux-gnu binutils-m68k-linux-gnu binutils-m68k-atari-mint qemu-user gpp 64tass nasm
+    apt install ninja-build lua5.1 libz80ex-dev flex libbsd-dev libreadline-dev bison binutils-arm-linux-gnueabihf binutils-i686-linux-gnu binutils-powerpc-linux-gnu binutils-m68k-linux-gnu binutils-m68k-atari-mint qemu-user gpp 64tass nasm python3
 
 Once done you can build the compiler itself with:
 
@@ -47,10 +47,10 @@ make
 ```
 
 You'll be left with a lot of stuff in the `bin` directory. The tools are all
-labeled as (name).(toolchain).(extension); however, several extensions also
-contain a dot.  So, `cowfe-65c02.ncpmz.z80.com` is cowfe, the main front-end
-compiler, targeting the 65c02, built with the `ncpmz` toolchain, which produced
-a `z80.com` executable.
+labeled as (name)-for-(toolchain)-with-(toolchain).  So,
+`cowfe-for-65c02-with-ncpmz.com` is cowfe, the main front-end compiler,
+targeting the 65c02, built with the `ncpmz` toolchain, which produced a `.com`
+executable.
 
 
 
diff --git a/examples/build.lua b/examples/build.lua
deleted file mode 100644
index 76d48d91..00000000
--- a/examples/build.lua
+++ /dev/null
@@ -1,20 +0,0 @@
-local PROGRAMS = {
-	"argv",
-	"file",
-	"filetester",
-	"helloworld",
-	"icando",
-	"mandel",
-}
-
-for _, toolchain in ipairs(ALL_TOOLCHAINS) do
-	for _, prog in ipairs(PROGRAMS) do
-        cowgol {
-                toolchain = toolchain,
-                ins = {
-                        "examples/"..prog..".cow"
-                },
-                outs = { "bin/examples/"..prog }
-        }
-	end
-end
diff --git a/examples/build.py b/examples/build.py
new file mode 100644
index 00000000..6b6fd288
--- /dev/null
+++ b/examples/build.py
@@ -0,0 +1,28 @@
+from src.build import cowgol
+from src.toolchains import TOOLCHAINS
+from build.ab2 import export
+
+PROGRAMS = [
+    "argv",
+    "file",
+    "filetester",
+    "helloworld",
+    "icando",
+    "mandel",
+]
+
+items = {}
+for toolchain in TOOLCHAINS:
+    toolchain.materialise()
+    for prog in PROGRAMS:
+        t = cowgol(
+            name=prog + "-for-" + toolchain.localname,
+            srcs="./" + prog + ".cow",
+            toolchain=toolchain,
+        )
+
+        items[
+            f"bin/examples/{prog}-for-{toolchain.localname}{toolchain.binext}"
+        ] = t
+
+export(name="examples", items=items)
diff --git a/mkninja.lua b/mkninja.lua
deleted file mode 100644
index b61a1b06..00000000
--- a/mkninja.lua
+++ /dev/null
@@ -1,184 +0,0 @@
-local function env(var, default)
-	return os.getenv(var) or default
-end
-
-print("OBJ = "..env("OBJ", ".obj"))
-print("LUA = "..env("LUA", "lua5.1"))
-print("CC = "..env("CC", "cc"))
-print("CXX = "..env("CC", "c++"))
-print("CPP = "..env("CC", "cpp"))
-print("AR = "..env("AR", "ar"))
-print("CFLAGS = "..env("CFLAGS", ""))
-print("CXXFLAGS = "..env("CXXFLAGS", "$CFLAGS"))
-print("LDFLAGS = "..env("LDFLAGS", ""))
-print("rule build");
-print("  command = $command");
-print("")
-
-function include(filename)
-	io.stderr:write("loading ", filename, "\n")
-	local fp, e = io.open(filename)
-	if not e then
-		local data
-		data, e = fp:read("*a")
-		fp:close();
-		if not e then
-			local chunk
-			chunk, e = loadstring(data, "@"..filename)
-			if not e then
-				chunk()
-			end
-		end
-	end
-	if e then
-		error(string.format("coudn't load %s: %s", filename, e))
-	end
-end
-
-function string:obj()
-	if not self:find("^%$") then
-		return "$OBJ/"..self
-	end
-	return self
-end
-
-function string:ext(newext)
-	return self:gsub("%.[^.]*$", newext)
-end
-
-function string:dir()
-	return self:gsub("[^/]*$", "")
-end
-
-function string:leaf()
-	return self:gsub("^.*/", "")
-end
-
-function concat(...)
-	local result = {}
-
-	local function recurse(t)
-		for _, i in ipairs(t) do
-			if type(i) == "table" then
-				recurse(i)
-			else
-				result[#result+1] = i
-			end
-		end
-	end
-	recurse({...})
-	return result
-end
-
-function joined(t)
-	local m = {}
-	for _, i in ipairs(t) do
-		m[i] = true
-	end
-	t = {}
-	for i in pairs(m) do
-		t[#t+1] = i
-	end
-	table.sort(t)
-	return table.concat(t, " ")
-end
-
-function set(t)
-	local s = {}
-	for _, k in ipairs(t) do
-		s[k] = true
-	end
-	return s
-end
-
-function command_present(name)
-	return os.execute("command -v "..name.." >/dev/null") ~= false
-end
-
-
-function rule(e)
-	print(string.format("build %s: build %s",
-		table.concat(e.outs, " "),
-		table.concat(e.ins, " ")))
-	local cmd = e.cmd
-		:gsub("@(%d+)", function (n) return e.ins[tonumber(n)] end)
-		:gsub("@@", table.concat(e.ins, " "))
-		:gsub("&(%d+)", function (n) return e.outs[tonumber(n)] end)
-
-	print("  command = "..cmd)
-	print("")
-end
-
-function addto(t, v)
-	t[#t+1] = v
-end
-
-function enable_if(name, command)
-	local v = command_present(command)
-	if not v then
-		io.stderr:write(name.." is 0 as "..command.." is not present\n")
-	end
-	_G[name] = v
-end
-
-enable_if("WITH_ATARITOS", "m68k-atari-mint-as")
-enable_if("WITH_MSDOS", "nasm")
-enable_if("WITH_LX386", "i686-linux-gnu-as")
-enable_if("WITH_LX68K", "m68k-linux-gnu-as")
-enable_if("WITH_LXTHUMB2", "arm-linux-gnueabihf-as")
-enable_if("WITH_LXPPC", "powerpc-linux-gnu-as")
-
-include "build/c.lua"
-include "build/yacc.lua"
-include "build/gpp.lua"
-include "build/tass64.lua"
-include "build/utils.lua"
-include "tools/build.lua"
-include "third_party/emu2/build.lua"
-include "third_party/apout/build.lua"
-include "third_party/zmac/build.lua"
-include "third_party/djlink/build.lua"
-include "third_party/musashi/build.lua"
-include "tools/cpmemu/build.lua"
-include "tools/tubeemu/build.lua"
-include "tools/fuzix6303emu/build.lua"
-include "tools/lx68kemu/build.lua"
-include "tools/ataritosemu/build.lua"
-include "tools/obpemu/build.lua"
-include "third_party/lemon/build.lua"
-include "tools/newgen/build.lua"
-include "src/build.lua"
-include "bootstrap/build.lua"
-include "toolchains.lua"
-include "src/cowlink/build.lua"
-include "src/cowfe/build.lua"
-include "src/cowbe/build.lua"
-include "src/cowwrap/build.lua"
-include "src/cowbdmp/build.lua"
-include "src/cowasm/build.lua"
-include "src/cowasm2/build.lua"
-include "src/cowdis/build.lua"
-include "src/misc/build.lua"
-include "rt/ataritos/build.lua"
-include "rt/cpm/build.lua"
-include "rt/cpmz/build.lua"
-include "rt/cgen/build.lua"
-include "rt/lx386/build.lua"
-include "rt/lx68k/build.lua"
-include "rt/lxthumb2/build.lua"
-include "rt/lxppc/build.lua"
-include "rt/bbct/build.lua"
-include "rt/bbcti/build.lua"
-include "rt/unixv7/build.lua"
-include "rt/fuzix6303/build.lua"
-include "rt/msdos/build.lua"
-include "examples/build.lua"
-include "tests/build.lua"
-include "dist/bbct/build.lua"
-include "dist/cpm/build.lua"
-include "dist/cpmz/build.lua"
-include "dist/cpmbasic/build.lua"
-include "dist/msdos/build.lua"
-include "dist/ataritos/build.lua"
-
-
diff --git a/rt/ataritos/build.lua b/rt/ataritos/build.lua
deleted file mode 100644
index 7bcc6414..00000000
--- a/rt/ataritos/build.lua
+++ /dev/null
@@ -1,6 +0,0 @@
-cowwrap {
-	ins = { "rt/common-68000/cowgol.cos" },
-	outs = { "$OBJ/rt/ataritos/cowgol.coo" }
-}
-
-
diff --git a/rt/ataritos/build.py b/rt/ataritos/build.py
new file mode 100644
index 00000000..1bedc025
--- /dev/null
+++ b/rt/ataritos/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="rt/common-68000/cowgol.cos")
diff --git a/rt/bbct/build.lua b/rt/bbct/build.lua
deleted file mode 100644
index 90a8a6bc..00000000
--- a/rt/bbct/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/bbct/cowgol.cos" },
-	outs = { "$OBJ/rt/bbct/cowgol.coo" }
-}
-
diff --git a/rt/bbct/build.py b/rt/bbct/build.py
new file mode 100644
index 00000000..b7594b3b
--- /dev/null
+++ b/rt/bbct/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="./cowgol.cos")
diff --git a/rt/bbcti/build.lua b/rt/bbcti/build.lua
deleted file mode 100644
index a391a768..00000000
--- a/rt/bbcti/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/bbcti/cowgol.cos" },
-	outs = { "$OBJ/rt/bbcti/cowgol.coo" }
-}
-
diff --git a/rt/cgen/build.lua b/rt/cgen/build.lua
deleted file mode 100644
index 192c139a..00000000
--- a/rt/cgen/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/cgen/cowgol.cos" },
-	outs = { "$OBJ/rt/cgen/cowgol.coo" }
-}
-
diff --git a/rt/cgen/build.py b/rt/cgen/build.py
new file mode 100644
index 00000000..b7594b3b
--- /dev/null
+++ b/rt/cgen/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="./cowgol.cos")
diff --git a/rt/cpm/build.lua b/rt/cpm/build.lua
deleted file mode 100644
index c7fdffe0..00000000
--- a/rt/cpm/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/cpm/cowgol.cos" },
-	outs = { "$OBJ/rt/cpm/cowgol.coo" }
-}
-
diff --git a/rt/cpm/build.py b/rt/cpm/build.py
new file mode 100644
index 00000000..b7594b3b
--- /dev/null
+++ b/rt/cpm/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="./cowgol.cos")
diff --git a/rt/cpmz/build.lua b/rt/cpmz/build.lua
deleted file mode 100644
index be847a05..00000000
--- a/rt/cpmz/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/cpmz/cowgol.cos" },
-	outs = { "$OBJ/rt/cpmz/cowgol.coo" }
-}
-
diff --git a/rt/cpmz/build.py b/rt/cpmz/build.py
new file mode 100644
index 00000000..b7594b3b
--- /dev/null
+++ b/rt/cpmz/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="./cowgol.cos")
diff --git a/rt/fuzix6303/build.lua b/rt/fuzix6303/build.lua
deleted file mode 100644
index b6b4fdfd..00000000
--- a/rt/fuzix6303/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/fuzix6303/cowgol.cos" },
-	outs = { "$OBJ/rt/fuzix6303/cowgol.coo" }
-}
-
diff --git a/rt/fuzix6303/build.py b/rt/fuzix6303/build.py
new file mode 100644
index 00000000..b7594b3b
--- /dev/null
+++ b/rt/fuzix6303/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="./cowgol.cos")
diff --git a/rt/lx386/build.lua b/rt/lx386/build.lua
deleted file mode 100644
index 2d7c0dd2..00000000
--- a/rt/lx386/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/lx386/cowgol.cos" },
-	outs = { "$OBJ/rt/lx386/cowgol.coo" }
-}
-
diff --git a/rt/lx386/build.py b/rt/lx386/build.py
new file mode 100644
index 00000000..b7594b3b
--- /dev/null
+++ b/rt/lx386/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="./cowgol.cos")
diff --git a/rt/lx68k/build.lua b/rt/lx68k/build.lua
deleted file mode 100644
index c8ba38a5..00000000
--- a/rt/lx68k/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/common-68000/cowgol.cos" },
-	outs = { "$OBJ/rt/lx68k/cowgol.coo" }
-}
-
diff --git a/rt/lx68k/build.py b/rt/lx68k/build.py
new file mode 100644
index 00000000..1bedc025
--- /dev/null
+++ b/rt/lx68k/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="rt/common-68000/cowgol.cos")
diff --git a/rt/lxppc/build.lua b/rt/lxppc/build.lua
deleted file mode 100644
index ed69d955..00000000
--- a/rt/lxppc/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/lxppc/cowgol.cos" },
-	outs = { "$OBJ/rt/lxppc/cowgol.coo" }
-}
-
diff --git a/rt/lxppc/build.py b/rt/lxppc/build.py
new file mode 100644
index 00000000..b7594b3b
--- /dev/null
+++ b/rt/lxppc/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="./cowgol.cos")
diff --git a/rt/lxppc/file.coh b/rt/lxppc/file.coh
index 73838f5b..0094bca6 100644
--- a/rt/lxppc/file.coh
+++ b/rt/lxppc/file.coh
@@ -29,7 +29,8 @@ include "fileio.coh";
 	@asm "lwz 8, ", pos, "@l(8)";
 	@asm "li 0, 0xb3"; # pread64
 	@asm "sc";
-	@asm "bsol ", _fix_errno;
+	@asm "bns . + 4";
+	@asm "bl ", _fix_errno;
 	@asm "lis 4, ", i, "@ha";
 	@asm "stw 3, ", i, "@l(4)";
 
@@ -58,7 +59,8 @@ end sub;
 	@asm "lwz 8, ", pos, "@l(8)";
 	@asm "li 0, 0xb4"; # pwrite64
 	@asm "sc";
-	@asm "bsol ", _fix_errno;
+	@asm "bns . + 4";
+	@asm "bl ", _fix_errno;
 	@asm "lis 4, ", i, "@ha";
 	@asm "stw 3, ", i, "@l(4)";
 
@@ -78,7 +80,8 @@ sub fcb_i_open(fcb: [FCB], filename: [uint8], flags: uint32): (errno: uint8) is
 	@asm "li 5, ", 0o666; # umask
 	@asm "li 0, 0x05"; # open
 	@asm "sc";
-	@asm "bsol ", _fix_errno;
+	@asm "bns . + 4";
+	@asm "bl ", _fix_errno;
 	@asm "lis 4, ", fd, "@ha";
 	@asm "stw 3, ", fd, "@l(4)";
 	if fd < 0 then
diff --git a/rt/lxthumb2/build.lua b/rt/lxthumb2/build.lua
deleted file mode 100644
index 9642e816..00000000
--- a/rt/lxthumb2/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/lxthumb2/cowgol.cos" },
-	outs = { "$OBJ/rt/lxthumb2/cowgol.coo" }
-}
-
diff --git a/rt/lxthumb2/build.py b/rt/lxthumb2/build.py
new file mode 100644
index 00000000..b7594b3b
--- /dev/null
+++ b/rt/lxthumb2/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="./cowgol.cos")
diff --git a/rt/msdos/build.lua b/rt/msdos/build.lua
deleted file mode 100644
index 9099e7e6..00000000
--- a/rt/msdos/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/msdos/cowgol.cos" },
-	outs = { "$OBJ/rt/msdos/cowgol.coo" }
-}
-
diff --git a/rt/msdos/build.py b/rt/msdos/build.py
new file mode 100644
index 00000000..b7594b3b
--- /dev/null
+++ b/rt/msdos/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="./cowgol.cos")
diff --git a/rt/unixv7/build.lua b/rt/unixv7/build.lua
deleted file mode 100644
index 7e616888..00000000
--- a/rt/unixv7/build.lua
+++ /dev/null
@@ -1,5 +0,0 @@
-cowwrap {
-	ins = { "rt/unixv7/cowgol.cos" },
-	outs = { "$OBJ/rt/unixv7/cowgol.coo" }
-}
-
diff --git a/rt/unixv7/build.py b/rt/unixv7/build.py
new file mode 100644
index 00000000..b7594b3b
--- /dev/null
+++ b/rt/unixv7/build.py
@@ -0,0 +1,3 @@
+from src.build import cowwrap
+
+cowwrap(name="cowgolcoo", src="./cowgol.cos")
diff --git a/src/build.lua b/src/build.lua
deleted file mode 100644
index 1a4a8c38..00000000
--- a/src/build.lua
+++ /dev/null
@@ -1,331 +0,0 @@
-rule {
-    ins = {
-        "scripts/mkiburgcodes.lua",
-        "scripts/libcowgol.lua",
-        "src/midcodes.coh.tab",
-    },
-    outs = { "$OBJ/iburgcodes-coh.h" },
-    cmd = "$LUA @1 -- @3 &1"
-}
-
-rule {
-    ins = {
-        "scripts/mkmidcodescoh.lua",
-        "scripts/libcowgol.lua",
-        "src/midcodes.coh.tab",
-    },
-    outs = { "$OBJ/midcodes.coh" },
-    cmd = "$LUA @1 -- @3 &1 combined"
-}
-
-rule {
-    ins = {
-        "scripts/mkcobin.lua",
-        "scripts/libcowgol.lua",
-        "src/midcodes.coh.tab",
-    },
-    outs = { "$OBJ/cobin.coh" },
-    cmd = "$LUA @1 -- @3 &1"
-}
-
-rule {
-    ins = {
-        "scripts/mkcobout.lua",
-        "scripts/libcowgol.lua",
-        "src/midcodes.coh.tab",
-    },
-    outs = { "$OBJ/cobout.coh" },
-    cmd = "$LUA @1 -- @3 &1"
-}
-
-rule {
-    ins = {
-        "scripts/mkmidcodescoh.lua",
-        "scripts/libcowgol.lua",
-        "src/midcodes.coh.tab",
-    },
-    outs = { "$OBJ/midcodesfe.coh" },
-    cmd = "$LUA @1 -- @3 &1 fe"
-}
-
-rule {
-    ins = {
-        "scripts/mkmidcodescoh.lua",
-        "scripts/libcowgol.lua",
-        "src/midcodes.coh.tab",
-    },
-    outs = { "$OBJ/midcodesbe.coh" },
-    cmd = "$LUA @1 -- @3 &1 be"
-}
-
-function uncoo(e)
-    rule {
-        ins = concat {
-            "scripts/uncoo.lua",
-            e.ins
-        },
-        outs = e.outs,
-        cmd = "$LUA @1 @2 &1"
-    }
-end
-
-function buildcgen(e)
-    cprogram {
-        ins = concat {
-            e.ins,
-            "rt/cgen/cowgol.h",
-        },
-        outs = e.outs
-    }
-end
-
-function buildgas(arch, e)
-    local obj = e.outs[1]:ext(".o"):obj()
-    rule {
-        ins = e.ins,
-        outs = { obj },
-        cmd = arch.."-as -g @1 -o &1"
-    }
-
-    rule {
-        ins = { obj },
-        outs = e.outs,
-        cmd = arch.."-ld -g @1 -o &1"
-    }
-end
-
-function buildgas386(e)
-    return buildgas("i686-linux-gnu", e)
-end
-
-function buildgas68k(e)
-    return buildgas("m68k-linux-gnu", e)
-end
-
-function buildgasarm(e)
-    return buildgas("arm-linux-gnueabihf", e)
-end
-
-function buildgasppc(e)
-	return buildgas("powerpc-linux-gnu", e)
-end
-
-function buildgasataritos(e)
-	return buildgas("m68k-atari-mint", e)
-end
-
-function buildzmac(e)
-    local cim = e.outs[1]:ext(".cim"):obj()
-    zmac {
-        ins = e.ins,
-        outs = { cim }
-    }
-
-    rule {
-        ins = { cim },
-        outs = e.outs,
-        cmd = "cp @1 &1"
-    }
-end
-
-function buildcowasm(e, asm)
-    local lst = e.outs[1]:ext(".lst"):obj()
-    rule {
-        ins = concat {
-            "scripts/quiet",
-            "bin/cowasm-"..asm..".nncgen.exe",
-            e.ins
-        },
-        outs = { e.outs[1], lst },
-        cmd = "@1 @2 @3 -o &1 -l &2"
-    }
-end
-
-function buildcowasm8080(e)
-    buildcowasm(e, "8080")
-end
-
-function buildcowasmpdp11(e)
-    buildcowasm(e, "pdp11")
-end
-
-function buildcowasm6303(e)
-    buildcowasm(e, "6303")
-end
-
-function buildtass64(e)
-    local img = e.outs[1]:ext(".img"):obj()
-    tass64 {
-        ins = e.ins,
-        outs = e.outs,
-    }
-end
-
-function buildnasm(e)
-    local lst = e.outs[1]:ext(".lst"):obj()
-    local obj = e.outs[1]:ext(".obj"):obj()
-    rule {
-        ins = e.ins,
-        outs = { obj, lst },
-        cmd = "nasm -f obj -o &1 -l &2 @1",
-    }
-
-    djlink {
-        ins = { obj },
-        outs = { e.outs[1] }
-    }
-end
-
-function simpletest(interpreter, e)
-    local badfile = e.ins[1]:ext(".bad")
-    rule {
-        ins = e.ins,
-        outs = { badfile },
-        cmd = "timeout 5s "..interpreter.." @1 > &1.tmp && mv &1.tmp &1 && diff -u -w &1 "..e.goodfile,
-    }
-end
-
-function nativetest(e)
-    return simpletest("", e)
-end
-
-function qemu386test(e)
-    return simpletest("qemu-i386", e)
-end
-
-function qemu68ktest(e)
-    return simpletest("qemu-m68k", e)
-end
-
-function qemuarmtest(e)
-    return simpletest("qemu-arm", e)
-end
-
-function qemuppctest(e)
-    return simpletest("qemu-ppc", e)
-end
-
-function cpmtest(e)
-    e.ins = concat { e.ins, "bin/cpmemu" }
-    return simpletest("bin/cpmemu", e)
-end
-
-function tubeemutest(e)
-    e.ins = concat { e.ins, "bin/tubeemu" }
-    return simpletest("bin/tubeemu -l 0x400 -e 0x400 -f", e)
-end
-
-function apouttest(e)
-    e.ins = concat { e.ins, "bin/apout" }
-    return simpletest("bin/apout ", e)
-end
-
-function fuzix6303test(e)
-    e.ins = concat { e.ins, "bin/fuzix6303emu" }
-    return simpletest("bin/fuzix6303emu -f", e)
-end
-
-function emu2test(e)
-    e.ins = concat { e.ins, "bin/emu2" }
-    return simpletest("bin/emu2", e)
-end
-
-function ataritosemutest(e)
-	e.ins = concat { e.ins, "bin/ataritosemu" }
-	return simpletest("bin/ataritosemu", e)
-end
-
-function cowgol(e)
-    local out = e.outs[1].."."..e.toolchain.name..e.toolchain.binext
-    local coo = out:ext(".coo"):obj()
-    local asm = out:ext(e.toolchain.asmext):obj()
-
-    local hdrs = {}
-    for _, src in ipairs(e.ins) do
-        local f = src:gsub("[^/]*$", "")
-        if f == "" then
-            f = "."
-        end
-        hdrs[#hdrs+1] = "-I"..f
-    end
-
-    if e.toolchain.compiler then
-        rule {
-            ins = concat {
-                e.toolchain.compiler,
-                e.ins,
-                "scripts/quiet",
-                "rt/common-file.coh",
-                "rt/common.coh",
-                "rt/fileio.coh",
-                "rt/malloc.coh",
-                "rt/strings.coh",
-                (e.toolchain.runtime.."/cowgol.coh"),
-                (e.toolchain.runtime.."/file.coh"),
-                (e.toolchain.runtime.."/argv.coh"),
-            },
-            outs = { coo },
-            cmd = "scripts/quiet @1 -Irt/ -I"..e.toolchain.runtime.."/ "..joined(hdrs).." @2 &1"
-        }
-    else
-        local cob = out:ext(".cob"):obj()
-        rule {
-            ins = concat {
-                e.toolchain.cowfe,
-                e.ins,
-                "scripts/quiet",
-                "rt/common-file.coh",
-                "rt/common.coh",
-                "rt/fileio.coh",
-                "rt/malloc.coh",
-                "rt/strings.coh",
-                (e.toolchain.runtime.."/cowgol.coh"),
-                (e.toolchain.runtime.."/file.coh"),
-                (e.toolchain.runtime.."/argv.coh"),
-            },
-            outs = { cob },
-            cmd = "scripts/quiet @1 -Irt/ -I"..e.toolchain.runtime.."/ "..joined(hdrs).." @2 &1"
-        }
-
-        rule {
-            ins = concat {
-                e.toolchain.cowbe,
-                "scripts/quiet",
-                cob,
-            },
-            outs = { coo },
-            cmd = "scripts/quiet @1 @3 &1"
-        }
-    end
-
-    rule {
-        ins = concat {
-            "scripts/quiet",
-            e.toolchain.linker,
-            (e.toolchain.runtime.."/cowgol.coo"):obj(),
-            coo
-        },
-        outs = { asm },
-        cmd = "@1 @2 -o &1 @3 @4"
-    }
-
-    e.toolchain.assembler {
-        ins = { asm },
-        outs = { out }
-    }
-
-    return out
-end
-
-function cowwrap(e)
-    rule {
-        ins = concat {
-            "scripts/quiet",
-            "bin/cowwrap.bootstrap.exe",
-            e.ins
-        },
-        outs = e.outs,
-        cmd = "@1 @2 @3 &1"
-    }
-end
-
diff --git a/src/build.py b/src/build.py
new file mode 100644
index 00000000..00cc4bad
--- /dev/null
+++ b/src/build.py
@@ -0,0 +1,165 @@
+from build.ab2 import (
+    Rule,
+    Target,
+    Targets,
+    export,
+    normalrule,
+    filenamesof,
+    filenameof,
+)
+from build.c import cprogram
+from os.path import *
+from types import SimpleNamespace
+import config
+
+
+@Rule
+def cowlib(
+    self,
+    name,
+    srcs: Targets = [],
+    deps: Targets = [],
+    toolchain: Target = None,
+):
+    srcs += [
+        "rt/common-file.coh",
+        "rt/common.coh",
+        "rt/fileio.coh",
+        "rt/malloc.coh",
+        "rt/strings.coh",
+        toolchain.runtime + "/cowgol.coh",
+        toolchain.runtime + "/file.coh",
+        toolchain.runtime + "/argv.coh",
+    ]
+
+    cow = [f for f in filenamesof(srcs) if f.endswith(".cow")]
+    dirs = set([dirname(f) for f in filenamesof(srcs)])
+    flags = [f"-I{dir}/" for dir in dirs]
+
+    cob = normalrule(
+        name=name + "/cowfe",
+        ins=[toolchain.cowfe, cow] + srcs,
+        outs=[self.localname + ".cob"],
+        commands=[
+            "scripts/quiet {ins[0]} "
+            + (" ".join(flags))
+            + " {ins[1]} {outs[0]}"
+        ],
+        label="COWFE-" + toolchain.localname.upper(),
+    )
+
+    normalrule(
+        replaces=self,
+        ins=[toolchain.cowbe, cob],
+        outs=[self.localname + ".coo"],
+        commands=["scripts/quiet {ins[0]} {ins[1]} {outs}"],
+        label="COWBE-" + toolchain.localname.upper(),
+    )
+
+
+@Rule
+def cowlink(self, name, deps: Targets = [], toolchain: Target = None):
+    coos = []
+    for d in deps:
+        if hasattr(d, "cowlib"):
+            coos += filenamesof(d)
+
+    asm = normalrule(
+        name=name + "/cowlink",
+        ins=[toolchain.cowlink] + [coos],
+        outs=[self.localname + toolchain.asmext],
+        commands=["scripts/quiet {ins[0]} -o {outs} {' '.join(ins[1:])}"],
+        label="COWLINK-" + toolchain.localname.upper(),
+    )
+
+    toolchain.assembler(replaces=self, srcs=[asm])
+
+
+@Rule
+def cowgol(
+    self,
+    name,
+    srcs: Targets = [],
+    deps: Targets = [],
+    toolchain: Target = None,
+):
+    coo = cowlib(name=name + "/main", srcs=srcs, toolchain=toolchain)
+
+    cowlink(
+        replaces=self,
+        deps=[coo, toolchain.runtime + "+cowgolcoo"] + deps,
+        toolchain=toolchain,
+    )
+
+
+@Rule
+def cowwrap(self, name, src: Target = None, toolchain: Target = "src+ncgen"):
+    self.cowlib = SimpleNamespace()
+    normalrule(
+        replaces=self,
+        ins=[toolchain.cowwrap, src],
+        outs=["cowgol.coo"],
+        label="COWWRAP-" + toolchain.localname.upper(),
+        commands=["scripts/quiet {ins[0]} {ins[1]} {outs}"],
+    )
+
+
+normalrule(
+    name="midcodesfecoh",
+    ins=[
+        "scripts/mkmidcodescoh.lua",
+        "scripts/libcowgol.lua",
+        "src/midcodes.coh.tab",
+    ],
+    outs=["midcodesfe.coh"],
+    commands=["lua {ins[0]} -- {ins[2]} {outs[0]} fe"],
+    label="MKMIDCODESFE",
+)
+
+normalrule(
+    name="midcodesbecoh",
+    ins=[
+        "scripts/mkmidcodescoh.lua",
+        "scripts/libcowgol.lua",
+        "src/midcodes.coh.tab",
+    ],
+    outs=["midcodesbe.coh"],
+    commands=["lua {ins[0]} -- {ins[2]} {outs[0]} be"],
+    label="MKMIDCODESBE",
+)
+
+normalrule(
+    name="coboutcoh",
+    ins=[
+        "scripts/mkcobout.lua",
+        "scripts/libcowgol.lua",
+        "src/midcodes.coh.tab",
+    ],
+    outs=["cobout.coh"],
+    commands=["lua {ins[0]} -- {ins[2]} {outs[0]}"],
+    label="MKCOBOUT",
+)
+
+normalrule(
+    name="iburgcodes",
+    ins=[
+        "scripts/mkiburgcodes.lua",
+        "scripts/libcowgol.lua",
+        "src/midcodes.coh.tab",
+    ],
+    outs=["iburgcodes-coh.h"],
+    commands=["lua {ins[0]} -- {ins[2]} {outs[0]}"],
+    label="MKIBURGCODES",
+)
+
+normalrule(
+    name="cobincoh",
+    ins=[
+        "scripts/mkcobin.lua",
+        "scripts/libcowgol.lua",
+        "src/midcodes.coh.tab",
+    ],
+    outs=["cobin.coh"],
+    commands=["lua {ins[0]} -- {ins[2]} {outs[0]}"],
+    label="MKCOBIN",
+)
diff --git a/src/cowasm/build.lua b/src/cowasm/build.lua
deleted file mode 100644
index f718424a..00000000
--- a/src/cowasm/build.lua
+++ /dev/null
@@ -1,16 +0,0 @@
-local ARCHS = { "8080", "pdp11", "6303", "tlcs90", "obp" }
-
-for _, toolchain in ipairs(ALL_TOOLCHAINS) do
-	for _, arch in ipairs(ARCHS) do
-		cowgol {
-			toolchain = toolchain,
-			ins = {
-				"src/cowasm/arch"..arch..".cow",
-				"src/cowasm/cowasm.coh",
-				"src/cowasm/stdsyms.coh",
-			},
-			outs = { "bin/cowasm-"..arch }
-		}
-	end
-end
-
diff --git a/src/cowasm/build.py b/src/cowasm/build.py
new file mode 100644
index 00000000..c99bb15d
--- /dev/null
+++ b/src/cowasm/build.py
@@ -0,0 +1,23 @@
+from build.ab2 import normalrule, export
+from src.build import cowgol
+from tools.newgen.build import newgencowgol
+from src.toolchains import TOOLCHAINS
+
+ARCHS = ["8080", "pdp11", "6303", "tlcs90", "obp"]
+
+items = {}
+for toolchain in TOOLCHAINS:
+    toolchain.materialise()
+    for arch in ARCHS:
+        name = "cowasm-for-" + arch + "-with-" + toolchain.localname
+        items[name] = cowgol(
+            name=name,
+            toolchain=toolchain,
+            srcs=[
+                "./arch" + arch + ".cow",
+                "./cowasm.coh",
+                "./stdsyms.coh",
+            ],
+        )
+
+export(name="cowasm", items=items)
diff --git a/src/cowasm2/build.lua b/src/cowasm2/build.lua
deleted file mode 100644
index 1ab65fe7..00000000
--- a/src/cowasm2/build.lua
+++ /dev/null
@@ -1,30 +0,0 @@
-local ARCHS = { "ac1082" }
-
-for _, arch in ipairs(ARCHS) do
-	lemoncowgol {
-		ins = { "src/cowasm2/arch"..arch..".y" },
-		outs = {
-			"$OBJ/src/cowasm2/arch"..arch..".parser.coh",
-			"$OBJ/src/cowasm2/arch"..arch..".tokens.coh",
-		}
-	}
-
-	for _, toolchain in ipairs(ALL_TOOLCHAINS) do
-		cowgol {
-			toolchain = toolchain,
-			ins = {
-				"src/cowasm2/arch"..arch..".cow",
-				"src/cowasm2/types.coh",
-				"src/cowasm2/lexer.coh",
-				"src/cowasm2/symbols.coh",
-				"src/cowasm2/emitter.coh",
-				"src/cowasm2/cowasm2.coh",
-				"$OBJ/src/cowasm2/arch"..arch..".parser.coh",
-				"$OBJ/src/cowasm2/arch"..arch..".tokens.coh",
-			},
-			outs = { "bin/cowasm-"..arch }
-		}
-	end
-end
-
-
diff --git a/src/cowbdmp/build.lua b/src/cowbdmp/build.lua
deleted file mode 100644
index 023fa89d..00000000
--- a/src/cowbdmp/build.lua
+++ /dev/null
@@ -1,16 +0,0 @@
-for _, toolchain in ipairs(ALL_TOOLCHAINS) do
-	cowgol {
-		toolchain = toolchain,
-		ins = {
-			"src/cowbdmp/main.cow",
-			"src/cowbdmp/types.coh",
-			"src/cowbe/inputter.coh",
-			"src/cowbe/utils.coh",
-			"src/cowbe/treewalker.coh",
-			"$OBJ/cobin.coh",
-			"$OBJ/midcodesbe.coh",
-		},
-		outs = { "bin/cowbdmp" }
-	}
-end
-
diff --git a/src/cowbdmp/build.py b/src/cowbdmp/build.py
new file mode 100644
index 00000000..85bcace0
--- /dev/null
+++ b/src/cowbdmp/build.py
@@ -0,0 +1,15 @@
+from build.ab2 import normalrule
+from src.build import cowgol
+from src.toolchains import TOOLCHAINS
+
+for toolchain in TOOLCHAINS:
+    cowgol(
+        name="cowbdmp-with-" + toolchain.localname,
+        toolchain=toolchain,
+        srcs=[
+            "./main.cow",
+            "./types.coh",
+            "src+midcodesbecoh",
+            "src+cobincoh",
+        ],
+    )
diff --git a/src/cowbe/build.lua b/src/cowbe/build.lua
deleted file mode 100644
index 484c1bc9..00000000
--- a/src/cowbe/build.lua
+++ /dev/null
@@ -1,61 +0,0 @@
-local ARCHS = {
-	"6303",
-	"6502",
-	"65c02",
-	"65c02-tiny",
-	"68000",
-	"80386",
-	"8080",
-	"8086",
-	"basic",
-	"cgen",
-	"pdp11",
-	"powerpc",
-	"thumb2",
-	"z80",
-}
-
-local extras = {
-	["65c02"] = "src/cowbe/arch6502.cow.ng",
-	["65c02-tiny"] = "src/cowbe/arch6502.cow.ng"
-}
-
-for _, arch in ipairs(ARCHS) do
-	newgencowgol {
-		ins = {
-			"src/cowbe/arch"..arch..".cow.ng",
-			extras[arch]
-		},
-		outs = {
-			"$OBJ/cowbe-"..arch.."/inssel.coh",
-			"$OBJ/cowbe-"..arch.."/inssel.decl.coh",
-		}
-	}
-end
-
-for _, toolchain in ipairs(ALL_TOOLCHAINS) do
-	for _, arch in ipairs(ARCHS) do
-		cowgol {
-			toolchain = toolchain,
-			ins = {
-				"src/cowbe/main.cow",
-				"include/coodecls.coh",
-				"src/cowbe/allocator.coh",
-				"src/cowbe/codegen.coh",
-				"src/cowbe/emitter.coh",
-				"src/cowbe/inputter.coh",
-				"src/cowbe/midcodec.coh",
-				"src/cowbe/processor.coh",
-				"src/cowbe/regcache.coh",
-				"src/cowbe/treewalker.coh",
-				"src/cowbe/types.coh",
-				"src/cowbe/utils.coh",
-				"$OBJ/cowbe-"..arch.."/inssel.coh",
-				"$OBJ/cowbe-"..arch.."/inssel.decl.coh",
-				"$OBJ/midcodesbe.coh",
-			},
-			outs = { "bin/cowbe-"..arch }
-		}
-	end
-end
-
diff --git a/src/cowbe/build.py b/src/cowbe/build.py
new file mode 100644
index 00000000..9e25119c
--- /dev/null
+++ b/src/cowbe/build.py
@@ -0,0 +1,60 @@
+from build.ab2 import normalrule, export
+from src.build import cowgol
+from src.toolchains import TOOLCHAINS
+from tools.newgen.build import newgencowgol
+
+ARCHS = [
+    "6303",
+    "6502",
+    "65c02",
+    "65c02-tiny",
+    "68000",
+    "80386",
+    "8080",
+    "8086",
+    "basic",
+    "cgen",
+    "pdp11",
+    "powerpc",
+    "thumb2",
+    "z80",
+]
+
+extras = {
+    "65c02": ["src/cowbe/arch6502.cow.ng"],
+    "65c02-tiny": ["src/cowbe/arch6502.cow.ng"],
+}
+
+for arch in ARCHS:
+    newgencowgol(
+        name="gen-" + arch,
+        srcs=["src/cowbe/arch" + arch + ".cow.ng"] + extras.get(arch, []),
+    )
+
+items = {}
+for toolchain in TOOLCHAINS:
+    for arch in ARCHS:
+        name = "cowbe-for-" + arch + "-with-" + toolchain.localname
+        items["bin/" + name] = cowgol(
+            name=name,
+            toolchain=toolchain,
+            srcs=[
+                "+gen-" + arch,
+                "include/coodecls.coh",
+                "src+midcodesbecoh",
+                "src+cobincoh",
+                "./main.cow",
+                "./allocator.coh",
+                "./codegen.coh",
+                "./emitter.coh",
+                "./inputter.coh",
+                "./midcodec.coh",
+                "./processor.coh",
+                "./regcache.coh",
+                "./treewalker.coh",
+                "./types.coh",
+                "./utils.coh",
+            ],
+        )
+
+export(name="cowbe", items=items)
diff --git a/src/cowdis/build.lua b/src/cowdis/build.lua
deleted file mode 100644
index 803c048b..00000000
--- a/src/cowdis/build.lua
+++ /dev/null
@@ -1,14 +0,0 @@
-local ARCHS = { "tlcs90" }
-
-for _, toolchain in ipairs(ALL_TOOLCHAINS) do
-	for _, arch in ipairs(ARCHS) do
-		cowgol {
-			toolchain = toolchain,
-			ins = {
-				"src/cowdis/arch"..arch..".cow",
-			},
-			outs = { "bin/cowdis-"..arch }
-		}
-	end
-end
-
diff --git a/src/cowdis/build.py b/src/cowdis/build.py
new file mode 100644
index 00000000..b4b4017a
--- /dev/null
+++ b/src/cowdis/build.py
@@ -0,0 +1,15 @@
+from build.ab2 import normalrule
+from src.build import cowgol
+from src.toolchains import TOOLCHAINS
+
+ARCHS = ["tlcs90"]
+
+for toolchain in TOOLCHAINS:
+    for arch in ARCHS:
+        cowgol(
+            name="cowdis-for-" + arch + "-with-" + toolchain.localname,
+            toolchain=toolchain,
+            srcs=[
+                "./arch" + arch + ".cow",
+            ],
+        )
diff --git a/src/cowfe/build.lua b/src/cowfe/build.lua
deleted file mode 100644
index d30f7810..00000000
--- a/src/cowfe/build.lua
+++ /dev/null
@@ -1,56 +0,0 @@
-local ARCHS = {
-	"6502",
-	"80386",
-	"basic",
-	"cgen",
-	"pdp11",
-	"16bit",
-	"32bita2",
-	"32bita",
-}
-
-lemoncowgol {
-	ins = { "src/cowfe/parser.y" },
-	outs = {
-		"$OBJ/src/cowfe/parser.coh",
-		"$OBJ/src/cowfe/parser.tokens.coh",
-	}
-}
-
-for _, arch in ipairs(ARCHS) do
-	rule {
-		ins = { "src/cowfe/arch"..arch..".coh" },
-		outs = { "$OBJ/cowfe-"..arch.."/arch.coh" },
-		cmd = "cp @1 &1",
-	}
-end
-
-for _, toolchain in ipairs(ALL_TOOLCHAINS) do
-	for _, arch in ipairs(ARCHS) do
-		cowgol {
-			toolchain = toolchain,
-			ins = {
-				"src/cowfe/main.cow",
-				"include/coodecls.coh",
-				"src/cowfe/allocator.coh",
-				"src/cowfe/codegen.coh",
-				"src/cowfe/emitter.coh",
-				"src/cowfe/expressions.coh",
-				"src/cowfe/lexer.coh",
-				"src/cowfe/midcodec.coh",
-				"src/cowfe/namespace.coh",
-				"src/cowfe/regcache.coh",
-				"src/cowfe/symbols.coh",
-				"src/cowfe/treewalker.coh",
-				"src/cowfe/types.coh",
-				"$OBJ/src/cowfe/parser.coh",
-				"$OBJ/src/cowfe/parser.tokens.coh",
-				"$OBJ/cowfe-"..arch.."/arch.coh",
-				"$OBJ/midcodesfe.coh",
-				"$OBJ/cobout.coh",
-			},
-			outs = { "bin/cowfe-"..arch }
-		}
-	end
-end
-
diff --git a/src/cowfe/build.py b/src/cowfe/build.py
new file mode 100644
index 00000000..711984e4
--- /dev/null
+++ b/src/cowfe/build.py
@@ -0,0 +1,56 @@
+from build.ab2 import normalrule, export
+from src.build import cowgol
+from src.toolchains import TOOLCHAINS
+from third_party.lemon.build import lemoncowgol
+
+ARCHS = [
+    "6502",
+    "80386",
+    "basic",
+    "cgen",
+    "pdp11",
+    "16bit",
+    "32bita2",
+    "32bita",
+]
+
+lemoncowgol(name="parser", src="src/cowfe/parser.y")
+
+for arch in ARCHS:
+    normalrule(
+        name="arch-" + arch,
+        ins=["./arch" + arch + ".coh"],
+        outs=["arch.coh"],
+        commands=["cp {ins} {outs}"],
+        label="COPY",
+    )
+
+items = {}
+for toolchain in TOOLCHAINS:
+    for arch in ARCHS:
+        name = "cowfe-for-" + arch + "-with-" + toolchain.localname
+        items[name] = cowgol(
+            name="cowfe-for-" + arch + "-with-" + toolchain.localname,
+            toolchain=toolchain,
+            srcs=[
+                "+arch-" + arch,
+                "+parser",
+                "./allocator.coh",
+                "./codegen.coh",
+                "./emitter.coh",
+                "./expressions.coh",
+                "./lexer.coh",
+                "./main.cow",
+                "./midcodec.coh",
+                "./namespace.coh",
+                "./regcache.coh",
+                "./symbols.coh",
+                "./treewalker.coh",
+                "./types.coh",
+                "include/coodecls.coh",
+                "src+coboutcoh",
+                "src+midcodesfecoh",
+            ],
+        )
+
+export(name="cowfe", items=items)
diff --git a/src/cowlink/build.lua b/src/cowlink/build.lua
deleted file mode 100644
index 567d7fea..00000000
--- a/src/cowlink/build.lua
+++ /dev/null
@@ -1,46 +0,0 @@
-local ARCHS = {
-	"8080",
-	"ataritos",
-	"basic",
-	"bbct",
-	"bbctn",
-	"cgen",
-	"fuzix6303",
-	"lx386",
-	"lx68k",
-	"lxppc",
-	"lxthumb2",
-	"msdos",
-	"rt11",
-	"v7unix",
-}
-
-for _, arch in ipairs(ARCHS) do
-	rule {
-		ins = { "src/cowlink/arch"..arch..".coh" },
-		outs = { "$OBJ/cowlink-"..arch.."/archlink.coh" },
-		cmd = "cp @1 &1",
-	}
-end
-
-for _, toolchain in ipairs(ALL_TOOLCHAINS) do
-	for _, arch in ipairs(ARCHS) do
-		cowgol {
-			toolchain = toolchain,
-			ins = {
-				"src/cowlink/main.cow",
-				"include/coodecls.coh",
-				"$OBJ/cowlink-"..arch.."/archlink.coh",
-				"src/cowlink/asmwrite.coh",
-				"src/cowlink/cooread.coh",
-				"src/cowlink/emitter.coh",
-				"src/cowlink/graph.coh",
-				"src/cowlink/streams.coh",
-				"src/cowlink/types.coh",
-				"src/cowlink/utils.coh",
-			},
-			outs = { "bin/cowlink-"..arch }
-		}
-	end
-end
-
diff --git a/src/cowlink/build.py b/src/cowlink/build.py
new file mode 100644
index 00000000..31c9d738
--- /dev/null
+++ b/src/cowlink/build.py
@@ -0,0 +1,51 @@
+from build.ab2 import normalrule, export
+from src.build import cowgol
+from src.toolchains import TOOLCHAINS
+
+ARCHS = [
+    "8080",
+    "ataritos",
+    "basic",
+    "bbct",
+    "bbctn",
+    "cgen",
+    "fuzix6303",
+    "lx386",
+    "lx68k",
+    "lxppc",
+    "lxthumb2",
+    "msdos",
+    "rt11",
+    "v7unix",
+]
+
+for arch in ARCHS:
+    normalrule(
+        name="arch-" + arch,
+        ins=["./arch" + arch + ".coh"],
+        outs=["archlink.coh"],
+        commands=["cp {ins} {outs}"],
+        label="COPY",
+    )
+
+items = {}
+for toolchain in TOOLCHAINS:
+    for arch in ARCHS:
+        name = "cowlink-for-" + arch + "-with-" + toolchain.localname
+        items[name] = cowgol(
+            name="cowlink-for-" + arch + "-with-" + toolchain.localname,
+            toolchain=toolchain,
+            srcs=[
+                "include/coodecls.coh",
+                "+arch-" + arch,
+                "./main.cow",
+                "./asmwrite.coh",
+                "./cooread.coh",
+                "./emitter.coh",
+                "./graph.coh",
+                "./streams.coh",
+                "./types.coh",
+                "./utils.coh",
+            ],
+        )
+export(name="cowlink", items=items)
diff --git a/src/cowwrap/build.lua b/src/cowwrap/build.lua
deleted file mode 100644
index efaadfee..00000000
--- a/src/cowwrap/build.lua
+++ /dev/null
@@ -1,13 +0,0 @@
-for _, toolchain in ipairs(ALL_TOOLCHAINS) do
-	cowgol {
-		toolchain = toolchain,
-		ins = {
-			"src/cowwrap/main.cow",
-			"include/coodecls.coh",
-			"src/cowwrap/emitter.coh",
-			"src/cowwrap/reader.coh",
-		},
-		outs = { "bin/cowwrap" },
-	}
-end
-
diff --git a/src/cowwrap/build.py b/src/cowwrap/build.py
new file mode 100644
index 00000000..13f9a5ce
--- /dev/null
+++ b/src/cowwrap/build.py
@@ -0,0 +1,18 @@
+from src.build import cowgol, export
+from src.toolchains import TOOLCHAINS
+
+items = {}
+for toolchain in TOOLCHAINS:
+    name = "cowwrap-with-" + toolchain.localname
+    items[name] = cowgol(
+        name=name,
+        toolchain=toolchain,
+        srcs=[
+            "include/coodecls.coh",
+            "./main.cow",
+            "./emitter.coh",
+            "./reader.coh",
+        ],
+    )
+
+export(name="cowwrap", items=items)
diff --git a/src/misc/build.lua b/src/misc/build.lua
deleted file mode 100644
index d0887c48..00000000
--- a/src/misc/build.lua
+++ /dev/null
@@ -1,11 +0,0 @@
-for _, toolchain in ipairs(ALL_TOOLCHAINS) do
-	cowgol {
-		toolchain = toolchain,
-		ins = {
-			"src/misc/basicify.cow"
-		},
-		outs = { "bin/basicify" }
-	}
-end
-
-
diff --git a/src/misc/build.py b/src/misc/build.py
new file mode 100644
index 00000000..4359b20a
--- /dev/null
+++ b/src/misc/build.py
@@ -0,0 +1,15 @@
+from build.ab2 import normalrule
+from src.build import cowgol
+from src.toolchains import TOOLCHAINS
+
+PROGRAMS = ["basicify"]
+
+for toolchain in TOOLCHAINS:
+    for program in PROGRAMS:
+        cowgol(
+            name=program + "-with-" + toolchain.localname,
+            toolchain=toolchain,
+            srcs=[
+                "./" + program + ".cow",
+            ],
+        )
diff --git a/src/toolchains.py b/src/toolchains.py
new file mode 100644
index 00000000..e8e72cac
--- /dev/null
+++ b/src/toolchains.py
@@ -0,0 +1,428 @@
+from build.ab2 import (
+    Rule,
+    Target,
+    Targets,
+    export,
+    normalrule,
+    filenamesof,
+    filenameof,
+)
+from build.c import cprogram
+from os.path import *
+from third_party.zmac.build import zmac
+from types import SimpleNamespace
+from build.tass64 import tass64
+from build.nasm import nasm
+from third_party.djlink.build import djlink
+import config
+
+
+@Rule
+def cgen(self, name, srcs: Targets = []):
+    cprogram(replaces=self, srcs=srcs + ["rt/cgen/cowgol.h"])
+
+
+def buildgasimpl(self, prefix, flags=""):
+    normalrule(
+        replaces=self,
+        ins=self.args["srcs"],
+        outs=[self.localname + ".elf"],
+        commands=[
+            prefix + "-as " + flags + " -g {ins} -o {outs[0]}.s",
+            prefix + "-ld -g {outs[0]}.s -o {outs[0]}",
+        ],
+        label="ASM-" + prefix.upper(),
+    )
+
+
+@Rule
+def buildgasarm(self, name, srcs: Targets = None):
+    buildgasimpl(self, "arm-linux-gnueabihf")
+
+
+@Rule
+def buildgas386(self, name, srcs: Targets = None):
+    buildgasimpl(self, "i686-linux-gnu")
+
+
+@Rule
+def buildgas68k(self, name, srcs: Targets = None):
+    buildgasimpl(self, "m68k-linux-gnu")
+
+
+@Rule
+def buildgasppc(self, name, srcs: Targets = None):
+    buildgasimpl(self, "powerpc-linux-gnu")
+
+
+@Rule
+def buildgasataritos(self, name, srcs: Targets = None):
+    buildgasimpl(self, "m68k-atari-mint")
+
+
+@Rule
+def buildtass64(self, name, srcs: Targets = None):
+    tass64(replaces=self, srcs=srcs)
+
+
+def buildcowasmimpl(self, asm):
+    normalrule(
+        replaces=self,
+        ins=[asm] + self.args["srcs"],
+        outs=[self.localname + ".bin"],
+        commands=["scripts/quiet {ins[0]} -o {outs[0]} {ins[1]}"],
+        label="ASM",
+    )
+
+
+@Rule
+def buildcowasmpdp11(self, name, srcs: Targets = None):
+    buildcowasmimpl(self, "src/cowasm+cowasm-for-pdp11-with-ncgen")
+
+
+@Rule
+def buildcowasm6303(self, name, srcs: Targets = None):
+    buildcowasmimpl(self, "src/cowasm+cowasm-for-6303-with-ncgen")
+
+
+@Rule
+def buildnasm(self, name, srcs: Targets = None):
+    o = nasm(name=name + "/obj", srcs=srcs)
+    djlink(replaces=self, srcs=[o])
+
+
+def testimpl(self, dep, command):
+    goodfile = self.args["goodfile"]
+    normalrule(
+        replaces=self,
+        ins=dep + [self.args["exe"]],
+        outs=[self.localname + ".bad"],
+        commands=[
+            "timeout 5s " + command + " > {outs}; true",
+            "diff -u -w {outs[0]} " + filenameof(goodfile),
+        ],
+        label="TEST",
+    )
+
+
+@Rule
+def nativetest(self, name, goodfile: Target = None, exe: Target = None):
+    testimpl(self, [], "{ins[0]}")
+
+
+@Rule
+def tubeemutest(self, name, goodfile: Target = None, exe: Target = None):
+    testimpl(self, ["tools/tubeemu"], "{ins[0]} -l 0x400 -e 0x400 -f {ins[1]}")
+
+
+@Rule
+def cpmtest(self, name, goodfile: Target = None, exe: Target = None):
+    testimpl(self, ["tools/cpmemu"], "{ins[0]} {ins[1]}")
+
+
+@Rule
+def apouttest(self, name, goodfile: Target = None, exe: Target = None):
+    testimpl(self, ["third_party/apout"], "{ins[0]} {ins[1]}")
+
+
+@Rule
+def fuzix6303test(self, name, goodfile: Target = None, exe: Target = None):
+    testimpl(self, ["tools/fuzix6303emu"], "{ins[0]} -f {ins[1]}")
+
+
+@Rule
+def ataritostest(self, name, goodfile: Target = None, exe: Target = None):
+    testimpl(self, ["tools/ataritosemu"], "{ins[0]} {ins[1]}")
+
+
+@Rule
+def qemuarmtest(self, name, goodfile: Target = None, exe: Target = None):
+    testimpl(self, [], "qemu-arm {ins[0]}")
+
+
+@Rule
+def qemu386test(self, name, goodfile: Target = None, exe: Target = None):
+    testimpl(self, [], "qemu-i386 {ins[0]}")
+
+
+@Rule
+def qemu68ktest(self, name, goodfile: Target = None, exe: Target = None):
+    testimpl(self, [], "qemu-m68k {ins[0]}")
+
+
+@Rule
+def qemuppctest(self, name, goodfile: Target = None, exe: Target = None):
+    testimpl(self, [], "qemu-ppc {ins[0]}")
+
+
+@Rule
+def msdostest(self, name, goodfile: Target = None, exe: Target = None):
+    testimpl(self, ["third_party/emu2"], "{ins[0]} {ins[1]}")
+
+
+@Rule
+def toolchain(
+    self,
+    name,
+    cowfe: Target = None,
+    cowbe: Target = None,
+    cowlink: Target = None,
+    cowwrap: Target = None,
+    runtime=None,
+    asmext=None,
+    binext=None,
+    assembler=None,
+    tester=None,
+):
+    id = self.localname
+
+    for k, v in self.args.items():
+        setattr(self, k, v)
+
+    items = {}
+    if cowfe:
+        items["bin/cowfe-" + id] = cowfe
+    if cowbe:
+        items["bin/cowbe-" + id] = cowbe
+    if cowlink:
+        items["bin/cowlink-" + id] = cowlink
+    if cowwrap:
+        items["bin/cowwrap-" + id] = cowwrap
+
+    export(replaces=self, items=items)
+
+
+TOOLCHAINS = []
+
+TOOLCHAINS.append(
+    toolchain(
+        name="ncgen",
+        cowfe="bootstrap+cowfe",
+        cowbe="bootstrap+cowbe",
+        cowlink="bootstrap+cowlink",
+        cowwrap="bootstrap+cowwrap",
+        runtime="rt/cgen",
+        asmext=".c",
+        binext=".exe",
+        assembler=cgen,
+    )
+)
+
+TOOLCHAINS.append(
+    toolchain(
+        name="nncgen",
+        cowfe="src/cowfe+cowfe-for-cgen-with-ncgen",
+        cowbe="src/cowbe+cowbe-for-cgen-with-ncgen",
+        cowlink="src/cowlink+cowlink-for-cgen-with-ncgen",
+        cowwrap="src/cowwrap+cowwrap-with-ncgen",
+        runtime="rt/cgen",
+        asmext=".c",
+        binext=".exe",
+        assembler=cgen,
+        tester=nativetest,
+    )
+)
+
+TOOLCHAINS.append(
+    toolchain(
+        name="ncpm",
+        cowfe="src/cowfe+cowfe-for-16bit-with-nncgen",
+        cowbe="src/cowbe+cowbe-for-8080-with-ncgen",
+        cowlink="src/cowlink+cowlink-for-8080-with-ncgen",
+        cowwrap="src/cowwrap+cowwrap-with-ncgen",
+        runtime="rt/cpm",
+        asmext=".asm",
+        binext=".com",
+        assembler=zmac,
+        tester=cpmtest,
+    )
+)
+
+TOOLCHAINS.append(
+    toolchain(
+        name="ncpmz",
+        cowfe="src/cowfe+cowfe-for-16bit-with-nncgen",
+        cowbe="src/cowbe+cowbe-for-z80-with-ncgen",
+        cowlink="src/cowlink+cowlink-for-8080-with-ncgen",
+        cowwrap="src/cowwrap+cowwrap-with-ncgen",
+        runtime="rt/cpmz",
+        asmext=".z80",
+        binext=".com",
+        assembler=zmac,
+        tester=cpmtest,
+    )
+)
+
+TOOLCHAINS.append(
+    toolchain(
+        name="unixv7",
+        cowfe="src/cowfe+cowfe-for-pdp11-with-nncgen",
+        cowbe="src/cowbe+cowbe-for-pdp11-with-ncgen",
+        cowlink="src/cowlink+cowlink-for-v7unix-with-ncgen",
+        cowwrap="src/cowwrap+cowwrap-with-ncgen",
+        runtime="rt/unixv7",
+        asmext=".asm",
+        binext=".exe",
+        assembler=buildcowasmpdp11,
+        tester=apouttest,
+    )
+)
+
+TOOLCHAINS.append(
+    toolchain(
+        name="fuzix6303",
+        cowfe="src/cowfe+cowfe-for-16bit-with-nncgen",
+        cowbe="src/cowbe+cowbe-for-6303-with-ncgen",
+        cowlink="src/cowlink+cowlink-for-fuzix6303-with-ncgen",
+        cowwrap="src/cowwrap+cowwrap-with-ncgen",
+        runtime="rt/fuzix6303",
+        asmext=".asm",
+        binext=".exe",
+        assembler=buildcowasm6303,
+        tester=fuzix6303test,
+    )
+)
+
+if config.has_lxthumb2:
+    TOOLCHAINS.append(
+        toolchain(
+            name="lxthumb2",
+            cowfe="src/cowfe+cowfe-for-32bita-with-nncgen",
+            cowbe="src/cowbe+cowbe-for-thumb2-with-ncgen",
+            cowlink="src/cowlink+cowlink-for-lxthumb2-with-ncgen",
+            cowwrap="src/cowwrap+cowwrap-with-ncgen",
+            runtime="rt/lxthumb2",
+            asmext=".s",
+            binext=".exe",
+            assembler=buildgasarm,
+            tester=qemuarmtest if config.has_qemuarm else None,
+        )
+    )
+
+if config.has_lx386:
+    TOOLCHAINS.append(
+        toolchain(
+            name="lx386",
+            cowfe="src/cowfe+cowfe-for-80386-with-nncgen",
+            cowbe="src/cowbe+cowbe-for-80386-with-ncgen",
+            cowlink="src/cowlink+cowlink-for-lx386-with-ncgen",
+            cowwrap="src/cowwrap+cowwrap-with-ncgen",
+            runtime="rt/lx386",
+            asmext=".s",
+            binext=".exe",
+            assembler=buildgas386,
+            tester=qemu386test if config.has_qemu386 else None,
+        )
+    )
+
+if config.has_lx68k:
+    TOOLCHAINS.append(
+        toolchain(
+            name="lx68k",
+            cowfe="src/cowfe+cowfe-for-32bita2-with-nncgen",
+            cowbe="src/cowbe+cowbe-for-68000-with-ncgen",
+            cowlink="src/cowlink+cowlink-for-lx68k-with-ncgen",
+            cowwrap="src/cowwrap+cowwrap-with-ncgen",
+            runtime="rt/lx68k",
+            asmext=".s",
+            binext=".exe",
+            assembler=buildgas68k,
+            tester=qemu68ktest if config.has_qemu68k else None,
+        )
+    )
+
+if config.has_lxppc:
+    TOOLCHAINS.append(
+        toolchain(
+            name="lxppc",
+            cowfe="src/cowfe+cowfe-for-32bita-with-nncgen",
+            cowbe="src/cowbe+cowbe-for-powerpc-with-ncgen",
+            cowlink="src/cowlink+cowlink-for-lxppc-with-ncgen",
+            cowwrap="src/cowwrap+cowwrap-with-ncgen",
+            runtime="rt/lxppc",
+            asmext=".s",
+            binext=".exe",
+            assembler=buildgasppc,
+            tester=qemuppctest if config.has_qemuppc else None,
+        )
+    )
+
+if config.has_bbct:
+    TOOLCHAINS.append(
+        toolchain(
+            name="bbct",
+            cowfe="src/cowfe+cowfe-for-6502-with-nncgen",
+            cowbe="src/cowbe+cowbe-for-65c02-with-ncgen",
+            cowlink="src/cowlink+cowlink-for-bbct-with-ncgen",
+            cowwrap="src/cowwrap+cowwrap-with-ncgen",
+            runtime="rt/bbct",
+            asmext=".asm",
+            binext=".bin",
+            assembler=buildtass64,
+            tester=tubeemutest,
+        )
+    )
+
+if config.has_bbctiny:
+    TOOLCHAINS.append(
+        toolchain(
+            name="bbctiny",
+            cowfe="src/cowfe+cowfe-for-6502-with-nncgen",
+            cowbe="src/cowbe+cowbe-for-65c02-tiny-with-ncgen",
+            cowlink="src/cowlink+cowlink-for-bbct-with-ncgen",
+            cowwrap="src/cowwrap+cowwrap-with-ncgen",
+            runtime="rt/bbct",
+            asmext=".asm",
+            binext=".bin",
+            assembler=buildtass64,
+            tester=tubeemutest,
+        )
+    )
+
+if config.has_bbct6502:
+    TOOLCHAINS.append(
+        toolchain(
+            name="bbct6502",
+            cowfe="src/cowfe+cowfe-for-6502-with-nncgen",
+            cowbe="src/cowbe+cowbe-for-6502-with-ncgen",
+            cowlink="src/cowlink+cowlink-for-bbct-with-ncgen",
+            cowwrap="src/cowwrap+cowwrap-with-ncgen",
+            runtime="rt/bbct",
+            asmext=".asm",
+            binext=".bin",
+            assembler=buildtass64,
+            tester=tubeemutest,
+        )
+    )
+
+if config.has_msdos:
+    TOOLCHAINS.append(
+        toolchain(
+            name="msdos",
+            cowfe="src/cowfe+cowfe-for-16bit-with-nncgen",
+            cowbe="src/cowbe+cowbe-for-8086-with-ncgen",
+            cowlink="src/cowlink+cowlink-for-msdos-with-ncgen",
+            cowwrap="src/cowwrap+cowwrap-with-ncgen",
+            runtime="rt/msdos",
+            asmext=".asm",
+            binext=".exe",
+            assembler=buildnasm,
+            tester=msdostest,
+        )
+    )
+
+if config.has_ataritos:
+    TOOLCHAINS.append(
+        toolchain(
+            name="ataritos",
+            cowfe="src/cowfe+cowfe-for-32bita2-with-nncgen",
+            cowbe="src/cowbe+cowbe-for-68000-with-ncgen",
+            cowlink="src/cowlink+cowlink-for-ataritos-with-ncgen",
+            cowwrap="src/cowwrap+cowwrap-with-ncgen",
+            runtime="rt/ataritos",
+            asmext=".asm",
+            binext=".tos",
+            assembler=buildgasataritos,
+            tester=ataritostest,
+        )
+    )
diff --git a/tests/build.lua b/tests/build.lua
deleted file mode 100644
index 894a807f..00000000
--- a/tests/build.lua
+++ /dev/null
@@ -1,72 +0,0 @@
-ALL_TESTS = {
-	"addsub-16bit",
-	"addsub-32bit",
-	"addsub-8bit",
-	"atoi",
-	"arrayinitialisers",
-	"case",
-	"casts",
-	"conditionals",
-	"divrem-16bit-s",
-	"divrem-16bit-u",
-	"divrem-32bit-s",
-	"divrem-32bit-u",
-	"divrem-8bit-s",
-	"divrem-8bit-u",
-	--"empty", # causes qemu to crash, but works on real hardware
-	"fileio",
-	"folding",
-	"forwards",
-	"inputparams",
-	"interfaces",
-	"itoa",
-	"logic-16bit",
-	"logic-32bit",
-	"logic-8bit",
-	"loops",
-	"lvalues",
-	"malloc",
-	"mul-16bit-s",
-	"mul-16bit-u",
-	"mul-32bit-s",
-	"mul-32bit-u",
-	"mul-8bit-s",
-	"mul-8bit-u",
-	"nested-calls",
-	"outputparams",
-	"pointers",
-	"rangetypes",
-	"recordinitialisers",
-	"records",
-	"regalloc",
-	"shifts-16bit",
-	"shifts-32bit",
-	"shifts-8bit",
-	"unions",
-}
-
-for _, toolchain in ipairs(ALL_TOOLCHAINS) do
-	-- ncgen uses the bootstrap compiler, which should be tested and also
-	-- doesn't support the current language features. So, we don't need to
-	-- run the tests for it and they likely won't work anyway.
-	if toolchain.name ~= "ncgen" then
-		for _, test in ipairs(ALL_TESTS) do
-			if toolchain.tester then
-				local exe = cowgol {
-					toolchain = toolchain,
-					ins = {
-						"tests/"..test..".test.cow",
-						"tests/_framework.coh",
-					},
-					outs = { "$OBJ/tests/"..test }
-				}
-
-				toolchain.tester {
-					ins = { exe },
-					goodfile = "tests/"..test..".good"
-				}
-			end
-		end
-	end
-end
-
diff --git a/tests/build.py b/tests/build.py
new file mode 100644
index 00000000..672cbfed
--- /dev/null
+++ b/tests/build.py
@@ -0,0 +1,87 @@
+from build.ab2 import normalrule, Rule, Target, export
+from src.build import cowgol
+from src.toolchains import TOOLCHAINS
+
+TESTS = [
+    "addsub-16bit",
+    "addsub-32bit",
+    "addsub-8bit",
+    "atoi",
+    "arrayinitialisers",
+    "case",
+    "casts",
+    "conditionals",
+    "divrem-16bit-s",
+    "divrem-16bit-u",
+    "divrem-32bit-s",
+    "divrem-32bit-u",
+    "divrem-8bit-s",
+    "divrem-8bit-u",
+    # "empty",  # causes qemu to crash, but works on real hardware
+    "fileio",
+    "folding",
+    "forwards",
+    "inputparams",
+    "interfaces",
+    "itoa",
+    "logic-16bit",
+    "logic-32bit",
+    "logic-8bit",
+    "loops",
+    "lvalues",
+    "malloc",
+    "mul-16bit-s",
+    "mul-16bit-u",
+    "mul-32bit-s",
+    "mul-32bit-u",
+    "mul-8bit-s",
+    "mul-8bit-u",
+    "nested-calls",
+    "outputparams",
+    "pointers",
+    "rangetypes",
+    "recordinitialisers",
+    "records",
+    "regalloc",
+    "shifts-16bit",
+    "shifts-32bit",
+    "shifts-8bit",
+    "unions",
+]
+
+
+@Rule
+def testsuite(self, name, toolchain: Target = None):
+    tests = []
+    if toolchain.tester:
+        for test in TESTS:
+            bin = cowgol(
+                name=name + "/" + test + "/bin",
+                srcs=["./" + test + ".test.cow"],
+                toolchain=toolchain,
+            )
+
+            tests.append(
+                toolchain.tester(
+                    name=name + "/" + test,
+                    goodfile="./" + test + ".good",
+                    exe=bin,
+                )
+            )
+
+    normalrule(
+        replaces=self,
+        ins=tests,
+        outs=["stamp"],
+        commands=["touch {outs}"],
+        label="TESTSUITE",
+    )
+
+
+export(
+    name="tests",
+    deps=[
+        testsuite(name="tests-" + toolchain.localname, toolchain=toolchain)
+        for toolchain in TOOLCHAINS
+    ],
+)
diff --git a/third_party/apout/build.lua b/third_party/apout/build.lua
deleted file mode 100644
index 22335627..00000000
--- a/third_party/apout/build.lua
+++ /dev/null
@@ -1,25 +0,0 @@
-cprogram {
-	ins = {
-		"third_party/apout/aout.c",
-		"third_party/apout/branch.c",
-		"third_party/apout/bsd_ioctl.c",
-		"third_party/apout/bsd_signal.c",
-		"third_party/apout/bsdtrap.c",
-		"third_party/apout/cpu.c",
-		"third_party/apout/debug.c",
-		"third_party/apout/double.c",
-		"third_party/apout/ea.c",
-		"third_party/apout/fp.c",
-		"third_party/apout/itab.c",
-		"third_party/apout/ke11a.c",
-		"third_party/apout/magic.c",
-		"third_party/apout/main.c",
-		"third_party/apout/single.c",
-		"third_party/apout/v1trap.c",
-		"third_party/apout/v7trap.c",
-	},
-	ldflags = "-lm",
-	cflags = "-DEMUV1 -DNATIVES -DRUN_V1_RAW -DDEBUG -DZERO_MEMORY -DWRITEBASE -DHEX",
-	outs = { "bin/apout" }
-}
-
diff --git a/third_party/apout/build.py b/third_party/apout/build.py
new file mode 100644
index 00000000..a94b3480
--- /dev/null
+++ b/third_party/apout/build.py
@@ -0,0 +1,36 @@
+from build.c import cprogram
+
+cprogram(
+    name="apout",
+    srcs=[
+        "./aout.c",
+        "./branch.c",
+        "./bsd_ioctl.c",
+        "./bsd_signal.c",
+        "./bsdtrap.c",
+        "./cpu.c",
+        "./debug.c",
+        "./double.c",
+        "./ea.c",
+        "./fp.c",
+        "./itab.c",
+        "./ke11a.c",
+        "./magic.c",
+        "./main.c",
+        "./single.c",
+        "./v1trap.c",
+        "./v7trap.c",
+    ],
+    vars={
+        "+ldflags": ["-lm"],
+        "+cflags": [
+            "-DEMUV1",
+            "-DNATIVES",
+            "-DRUN_V1_RAW",
+            "-DDEBUG",
+            "-DZERO_MEMORY",
+            "-DWRITEBASE",
+            "-DHEX",
+        ],
+    },
+)
diff --git a/third_party/djlink/build.lua b/third_party/djlink/build.lua
deleted file mode 100644
index 552b5288..00000000
--- a/third_party/djlink/build.lua
+++ /dev/null
@@ -1,54 +0,0 @@
-cxxprogram {
-	ins = { "third_party/djlink/objdump.cc" },
-	outs = { "bin/objdump" }
-}
-
-cxxprogram {
-	ins = { "third_party/djlink/bindiff.cc" },
-	outs = { "bin/bindiff" }
-}
-
-cxxprogram {
-	ins = {
-		"third_party/djlink/djlink.cc",
-		"third_party/djlink/fixups.cc",
-		"third_party/djlink/libs.cc",
-		"third_party/djlink/list.cc",
-		"third_party/djlink/map.cc",
-		"third_party/djlink/objs.cc",
-		"third_party/djlink/out.cc",
-		"third_party/djlink/quark.cc",
-		"third_party/djlink/segments.cc",
-		"third_party/djlink/stricmp.cc",
-		"third_party/djlink/symbols.cc",
-		"third_party/djlink/fixups.h",
-		"third_party/djlink/libs.h",
-		"third_party/djlink/link.h",
-		"third_party/djlink/list.h",
-		"third_party/djlink/map.h",
-		"third_party/djlink/objs.h",
-		"third_party/djlink/omf.h",
-		"third_party/djlink/out.h",
-		"third_party/djlink/quark.h",
-		"third_party/djlink/segments.h",
-		"third_party/djlink/stricmp.h",
-		"third_party/djlink/symbols.h",
-		"third_party/djlink/vars.h",
-	},
-	outs = { "bin/djlink" }
-}
-
-function djlink(e)
-	local map = e.outs[1]:ext(".map")
-	rule {
-		ins = concat {
-			"bin/djlink",
-			e.ins,
-		},
-		outs = concat {
-			e.outs,
-			map
-		},
-		cmd = "@1 -o &1 -m &2 @2 > /dev/null"
-	}
-end 
diff --git a/third_party/djlink/build.py b/third_party/djlink/build.py
new file mode 100644
index 00000000..cb16c0a4
--- /dev/null
+++ b/third_party/djlink/build.py
@@ -0,0 +1,62 @@
+from build.c import cxxprogram
+from build.ab2 import export, Rule, Targets, normalrule
+
+cxxprogram(
+    name="objdump",
+    srcs=["./objdump.cc"],
+)
+
+cxxprogram(
+    name="bindiff",
+    srcs=["./bindiff.cc"],
+)
+
+cxxprogram(
+    name="djlink",
+    srcs=[
+        "./djlink.cc",
+        "./fixups.cc",
+        "./libs.cc",
+        "./list.cc",
+        "./map.cc",
+        "./objs.cc",
+        "./out.cc",
+        "./quark.cc",
+        "./segments.cc",
+        "./stricmp.cc",
+        "./symbols.cc",
+        "./fixups.h",
+        "./libs.h",
+        "./link.h",
+        "./list.h",
+        "./map.h",
+        "./objs.h",
+        "./omf.h",
+        "./out.h",
+        "./quark.h",
+        "./segments.h",
+        "./stricmp.h",
+        "./symbols.h",
+        "./vars.h",
+    ],
+)
+
+export(
+    name="djlink-programs",
+    items={
+        "bin/objdump": "+objdump",
+        "bin/bindiff": "+bindiff",
+        "bin/djlink": "+djlink",
+    },
+)
+
+
+@Rule
+def djlink(self, name, srcs: Targets = []):
+    normalrule(
+        replaces=self,
+        ins=["third_party/djlink"] + srcs,
+        outs=[self.localname + ".bin"],
+        commands=["{ins[0]} -o {outs} {ins[1]} > /dev/null"],
+        label="DJLINK",
+    )
diff --git a/third_party/emu2/build.lua b/third_party/emu2/build.lua
deleted file mode 100644
index 65b6a29e..00000000
--- a/third_party/emu2/build.lua
+++ /dev/null
@@ -1,19 +0,0 @@
-cprogram {
-	ins = {
-		"third_party/emu2/src/cpu.c",
-		"third_party/emu2/src/loader.c",
-		"third_party/emu2/src/main.c",
-		"third_party/emu2/src/codepage.c",
-		"third_party/emu2/src/dosnames.c",
-		"third_party/emu2/src/dis.c",
-		"third_party/emu2/src/dos.c",
-		"third_party/emu2/src/keyb.c",
-		"third_party/emu2/src/dbg.c",
-		"third_party/emu2/src/timer.c",
-		"third_party/emu2/src/utils.c",
-		"third_party/emu2/src/video.c",
-	},
-	ldflags = "-lm",
-	outs = { "bin/emu2" }
-}
-
diff --git a/third_party/emu2/build.py b/third_party/emu2/build.py
new file mode 100644
index 00000000..b731d236
--- /dev/null
+++ b/third_party/emu2/build.py
@@ -0,0 +1,20 @@
+from build.c import cprogram
+
+cprogram(
+    name="emu2",
+    srcs=[
+        "./src/cpu.c",
+        "./src/loader.c",
+        "./src/main.c",
+        "./src/codepage.c",
+        "./src/dosnames.c",
+        "./src/dis.c",
+        "./src/dos.c",
+        "./src/keyb.c",
+        "./src/dbg.c",
+        "./src/timer.c",
+        "./src/utils.c",
+        "./src/video.c",
+    ],
+    vars={"+ldflags": ["-lm"]},
+)
diff --git a/third_party/lemon/build.lua b/third_party/lemon/build.lua
deleted file mode 100644
index eef67b95..00000000
--- a/third_party/lemon/build.lua
+++ /dev/null
@@ -1,41 +0,0 @@
-cprogram {
-	ins = { "third_party/lemon/lemon.c" },
-	outs = { "bin/lemon" }
-}
-
-cprogram {
-	ins = { "third_party/lemon/lemon-cowgol.c" },
-	outs = { "bin/lemon-cowgol" }
-}
-
-function lemon(e)
-	local dir = e.outs[1]:gsub("/[^/]*$", "").."/tmp"
-	rule {
-		ins = concat {
-			"bin/lemon",
-			"third_party/lemon/lempar.c",
-			e.ins,
-		},
-		outs = e.outs,
-		cmd = "mkdir -p "..dir.." && @1 -T@2 -d"..dir.." @3"
-			.." && mv "..dir.."/parser.c &1"
-			.." && mv "..dir.."/parser.h &2"
-	}
-end
-
-function lemoncowgol(e)
-	local dir = e.outs[1]:gsub("/[^/]*$", "").."/tmp"
-	local leaf = e.ins[1]:leaf():ext("")
-	rule {
-		ins = concat {
-			"bin/lemon-cowgol",
-			"src/cowfe/lempar.coh",
-			e.ins,
-		},
-		outs = e.outs,
-		cmd = "mkdir -p "..dir.." && @1 -T@2 -d"..dir.." @3"
-			.." && mv "..dir.."/"..leaf..".c &1"
-			.." && mv "..dir.."/"..leaf..".h &2"
-	}
-end
-
diff --git a/third_party/lemon/build.py b/third_party/lemon/build.py
new file mode 100644
index 00000000..ad348e1c
--- /dev/null
+++ b/third_party/lemon/build.py
@@ -0,0 +1,34 @@
+from build.ab2 import Rule, Target, normalrule
+from build.c import cprogram
+
+cprogram(
+    name="lemon",
+    srcs=["./lemon.c"],
+)
+
+cprogram(
+    name="lemon-cowgol",
+    srcs=["./lemon-cowgol.c"],
+)
+
+
+@Rule
+def lemon(self, name, src: Target = None):
+    normalrule(
+        replaces=self,
+        ins=["third_party/lemon+lemon", "third_party/lemon/lempar.c", src],
+        outs=[self.localname + ".c", self.localname + ".h"],
+        commands=["{ins[0]} -T{ins[1]} -d{dirname(outs[0])} {ins[2]}"],
+        label="LEMON",
+    )
+
+
+@Rule
+def lemoncowgol(self, name, src: Target = None):
+    normalrule(
+        replaces=self,
+        ins=["third_party/lemon+lemon-cowgol", "src/cowfe/lempar.coh", src],
+        outs=[self.localname + ".coh", self.localname + ".tokens.coh"],
+        commands=["{ins[0]} -T{ins[1]} -d{dirname(outs[0])} {ins[2]}"],
+        label="LEMON-COWGOL",
+    )
diff --git a/third_party/lemon/lemon-cowgol.c b/third_party/lemon/lemon-cowgol.c
index 760d7031..4c2f3242 100644
--- a/third_party/lemon/lemon-cowgol.c
+++ b/third_party/lemon/lemon-cowgol.c
@@ -4104,7 +4104,7 @@ void ReportTable(
 
   in = tplt_open(lemp);
   if( in==0 ) return;
-  out = file_open(lemp,".c","wb");
+  out = file_open(lemp,".coh","wb");
   if( out==0 ){
     fclose(in);
     return;
@@ -4115,7 +4115,7 @@ void ReportTable(
   /* Generate the include code, if any */
   tplt_print(out,lemp,lemp->include,&lineno);
   if( mhflag ){
-    char *incName = file_makename(lemp, ".h");
+    char *incName = file_makename(lemp, ".tokens.coh");
     fprintf(out,"#include \"%s\"\n", incName); lineno++;
     free(incName);
   }
@@ -4625,22 +4625,7 @@ void ReportHeader(struct lemon *lemp)
 
   if( lemp->tokenprefix ) prefix = lemp->tokenprefix;
   else                    prefix = "";
-  in = file_open(lemp,".h","rb");
-  if( in ){
-    int nextChar;
-    for(i=1; i<lemp->nterminal && fgets(line,LINESIZE,in); i++){
-      lemon_sprintf(pattern,"const %s%s := %d;\n",
-                    prefix,lemp->symbols[i]->name,i);
-      if( strcmp(line,pattern) ) break;
-    }
-    nextChar = fgetc(in);
-    fclose(in);
-    if( i==lemp->nterminal && nextChar==EOF ){
-      /* No change in the file.  Don't rewrite it. */
-      return;
-    }
-  }
-  out = file_open(lemp,".h","wb");
+  out = file_open(lemp,".tokens.coh","wb");
   if( out ){
     for(i=1; i<lemp->nterminal; i++){
       fprintf(out,"const %s%s := %d;\n",prefix,lemp->symbols[i]->name,i);
diff --git a/third_party/lib6502/build.py b/third_party/lib6502/build.py
new file mode 100644
index 00000000..1b39e44d
--- /dev/null
+++ b/third_party/lib6502/build.py
@@ -0,0 +1,7 @@
+from build.c import clibrary
+
+clibrary(
+    name="lib6502",
+    srcs=["./lib6502.c"],
+    hdrs=["./lib6502.h"],
+)
diff --git a/third_party/musashi/build.lua b/third_party/musashi/build.lua
deleted file mode 100644
index af53f7fa..00000000
--- a/third_party/musashi/build.lua
+++ /dev/null
@@ -1,40 +0,0 @@
-cprogram {
-	ins = {
-		"third_party/musashi/m68kmake.c"
-	},
-	outs = {
-		"$OBJ/third_party/musashi/m68kmake"
-	}
-}
-
-rule {
-	ins = {
-		"$OBJ/third_party/musashi/m68kmake",
-		"third_party/musashi/m68k_in.c"
-	},
-	outs = {
-		"$OBJ/third_party/musashi/m68kops.c",
-		"$OBJ/third_party/musashi/m68kops.h"
-	},
-	cmd = "@1 $OBJ/third_party/musashi @2 > /dev/null"
-}
-
-function musashilib(e)
-	clibrary {
-		ins = {
-			e.m68kconf,
-			"third_party/musashi/m68kcpu.c",
-			"third_party/musashi/m68kcpu.h",
-			"third_party/musashi/m68kdasm.c",
-			"third_party/musashi/m68k.h",
-			"third_party/musashi/m68kmmu.h",
-			"third_party/musashi/softfloat/softfloat.c",
-			"third_party/musashi/softfloat/softfloat.h",
-			"$OBJ/third_party/musashi/m68kops.c",
-			"$OBJ/third_party/musashi/m68kops.h"
-		},
-		objdir = e.outs[1]:dir().."musashi",
-		outs = e.outs
-	}
-end
-
diff --git a/third_party/musashi/build.py b/third_party/musashi/build.py
new file mode 100644
index 00000000..ae8db58a
--- /dev/null
+++ b/third_party/musashi/build.py
@@ -0,0 +1,30 @@
+from build.ab2 import Rule, Target, normalrule
+from build.c import clibrary, cprogram
+
+cprogram(name="m68kmake", srcs=["./m68kmake.c"])
+
+normalrule(
+    name="m68kops",
+    ins=["+m68kmake", "./m68k_in.c"],
+    outs=["m68kops.c", "m68kops.h"],
+    commands=["{ins[0]} {dirname(outs[0])} {ins[1]} > /dev/null"],
+    label="MUSASHILIB",
+)
+
+
+@Rule
+def musashilib(self, name, m68kconf: Target = None):
+    clibrary(
+        replaces=self,
+        srcs=[
+            m68kconf,
+            "third_party/musashi/m68kcpu.c",
+            "third_party/musashi/m68kcpu.h",
+            "third_party/musashi/m68kdasm.c",
+            "third_party/musashi/m68k.h",
+            "third_party/musashi/m68kmmu.h",
+            "third_party/musashi/softfloat/softfloat.c",
+            "third_party/musashi/softfloat/softfloat.h",
+            "third_party/musashi+m68kops",
+        ],
+    )
diff --git a/third_party/rc2014emu/build.lua b/third_party/rc2014emu/build.lua
deleted file mode 100644
index e69de29b..00000000
diff --git a/third_party/rc2014emu/build.py b/third_party/rc2014emu/build.py
new file mode 100644
index 00000000..e1bae79d
--- /dev/null
+++ b/third_party/rc2014emu/build.py
@@ -0,0 +1,3 @@
+from build.c import clibrary
+
+clibrary(name="rc2014emu", srcs=["./6800.c"], hdrs=["./6800.h"])
diff --git a/third_party/zmac/build.lua b/third_party/zmac/build.lua
deleted file mode 100644
index 06614293..00000000
--- a/third_party/zmac/build.lua
+++ /dev/null
@@ -1,44 +0,0 @@
-yacc {
-	ins = { "third_party/zmac/zmac.y" },
-	outs = {
-		"$OBJ/third_party/zmac/y.tab.c",
-		"$OBJ/third_party/zmac/y.tab.h",
-	}
-}
-
-cprogram {
-	ins = {
-		"$OBJ/third_party/zmac/y.tab.c",
-		"third_party/zmac/mio.c",
-		"third_party/zmac/zi80dis.cpp"
-	},
-	outs = {
-		"bin/zmac"
-	},
-	cflags = "-I$OBJ/third_party/zmac -Ithird_party/zmac"
-}
-
-function zmac(e)
-	local f = e.ins[1]
-	local _, _, ext = f:find("%.(%w+)$")
-	local archflag = (ext == "z80") and "-z" or "-8"
-	local lstfile = e.outs[1]:ext(".lst")
-
-	local hdrpaths = {}
-	for _, t in ipairs(e.ins) do
-		hdrpaths[#hdrpaths+1] = "-I"..t
-	end
-
-	rule {
-		ins = concat(
-			"bin/zmac",
-			e.ins
-		),
-		outs = {
-			e.outs[1],
-			lstfile
-		},
-		cmd = "@1 -j -m "..archflag.." -o &1 -o &2 "..table.concat(hdrpaths, " ").." @2"
-	}
-end
-
diff --git a/third_party/zmac/build.py b/third_party/zmac/build.py
new file mode 100644
index 00000000..911ca726
--- /dev/null
+++ b/third_party/zmac/build.py
@@ -0,0 +1,35 @@
+from build.yacc import yacc
+from build.c import cprogram
+from build.ab2 import Rule, Targets, normalrule, filenameof
+from os.path import *
+
+yacc(
+    name="parser",
+    srcs=["third_party/zmac/zmac.y"],
+)
+
+cprogram(
+    name="zmac",
+    srcs=["+parser", "./mio.c", "./zi80dis.cpp", "./zi80dis.h"],
+    vars={
+        "+cflags": ["-Ithird_party/zmac"],
+    },
+)
+
+
+@Rule
+def zmac(self, name, srcs: Targets = []):
+    filename, ext = splitext(filenameof(srcs))
+    archflag = "-z" if (ext == ".z80") else "-8"
+
+    normalrule(
+        replaces=self,
+        ins=["third_party/zmac", srcs[0]],
+        outs=[self.localname + ".cim"],
+        commands=[
+            "{ins[0]} -j -m "
+            + archflag
+            + " -o {outs[0]} -o {outs[0]}.lst {ins[1]}"
+        ],
+        label="ZMAC",
+    )
diff --git a/toolchains.lua b/toolchains.lua
deleted file mode 100644
index 7ea33425..00000000
--- a/toolchains.lua
+++ /dev/null
@@ -1,202 +0,0 @@
-toolchain_ataritos = {
-	name = "ataritos",
-	cowfe = "bin/cowfe-32bita2.nncgen.exe",
-	cowbe = "bin/cowbe-68000.nncgen.exe",
-	linker = "bin/cowlink-ataritos.nncgen.exe",
-	assembler = buildgasataritos,
-	runtime = "rt/ataritos",
-	asmext = ".s",
-	binext = ".ataritos.tos",
-	tester = ataritosemutest,
-}
-
-toolchain_ncgen = {
-	name = "ncgen",
-	cowfe = "bin/cowfe-cgen.bootstrap.exe",
-	cowbe = "bin/cowbe-cgen.bootstrap.exe",
-	linker = "bin/cowlink-cgen.bootstrap.exe",
-	assembler = buildcgen,
-	runtime = "rt/cgen",
-	asmext = ".c",
-	binext = ".exe",
-	tester = nativetest
-}
-
-toolchain_nncgen = {
-	name = "nncgen",
-	cowbe = "bin/cowbe-cgen.ncgen.exe",
-	cowfe = "bin/cowfe-cgen.ncgen.exe",
-	linker = "bin/cowlink-cgen.ncgen.exe",
-	assembler = buildcgen,
-	runtime = "rt/cgen",
-	asmext = ".c",
-	binext = ".exe",
-	tester = nativetest
-}
-
-toolchain_ncpm = {
-	name = "ncpm",
-	cowfe = "bin/cowfe-16bit.nncgen.exe",
-	cowbe = "bin/cowbe-8080.nncgen.exe",
-	linker = "bin/cowlink-8080.nncgen.exe",
-	assembler = buildcowasm8080,
-	runtime = "rt/cpm",
-	asmext = ".asm",
-	binext = ".8080.com",
-	tester = cpmtest,
-}
-
-toolchain_ncpmz = {
-	name = "ncpmz",
-	cowfe = "bin/cowfe-16bit.nncgen.exe",
-	cowbe = "bin/cowbe-z80.nncgen.exe",
-	linker = "bin/cowlink-8080.nncgen.exe",
-	assembler = buildzmac,
-	runtime = "rt/cpmz",
-	asmext = ".z80",
-	binext = ".z80.com",
-	tester = cpmtest,
-}
-
-toolchain_lxthumb2 = {
-	name = "lxthumb2",
-	cowfe = "bin/cowfe-32bita.nncgen.exe",
-	cowbe = "bin/cowbe-thumb2.nncgen.exe",
-	linker = "bin/cowlink-lxthumb2.nncgen.exe",
-	assembler = buildgasarm,
-	runtime = "rt/lxthumb2",
-	asmext = ".s",
-	binext = ".lxthumb2.exe",
-	tester = qemuarmtest
-}
-
-toolchain_lx386 = {
-	name = "lx386",
-	cowfe = "bin/cowfe-80386.nncgen.exe",
-	cowbe = "bin/cowbe-80386.nncgen.exe",
-	linker = "bin/cowlink-lx386.nncgen.exe",
-	assembler = buildgas386,
-	runtime = "rt/lx386",
-	asmext = ".s",
-	binext = ".lx386.exe",
-	tester = qemu386test
-}
-
-toolchain_lx68k = {
-	name = "lx68k",
-	cowfe = "bin/cowfe-32bita2.nncgen.exe",
-	cowbe = "bin/cowbe-68000.nncgen.exe",
-	linker = "bin/cowlink-lx68k.nncgen.exe",
-	assembler = buildgas68k,
-	runtime = "rt/lx68k",
-	asmext = ".s",
-	binext = ".lx68k.exe",
-	tester = qemu68ktest
-}
-
-toolchain_lxppc = {
-	name = "lxppc",
-	cowfe = "bin/cowfe-32bita.nncgen.exe",
-	cowbe = "bin/cowbe-powerpc.nncgen.exe",
-	linker = "bin/cowlink-lxppc.nncgen.exe",
-	assembler = buildgasppc,
-	runtime = "rt/lxppc",
-	asmext = ".s",
-	binext = ".lxppc.exe",
-	tester = qemuppctest
-}
-
-toolchain_bbct = {
-	name = "bbct",
-	cowfe = "bin/cowfe-6502.nncgen.exe",
-	cowbe = "bin/cowbe-65c02.nncgen.exe",
-	linker = "bin/cowlink-bbct.nncgen.exe",
-	assembler = buildtass64,
-	runtime = "rt/bbct",
-	asmext = ".asm",
-	binext = ".bbct",
-	tester = tubeemutest,
-	archs = { "8080" }
-}
-
-toolchain_bbctiny = {
-	name = "bbctiny",
-	cowfe = "bin/cowfe-6502.nncgen.exe",
-	cowbe = "bin/cowbe-65c02-tiny.nncgen.exe",
-	linker = "bin/cowlink-bbct.nncgen.exe",
-	assembler = buildtass64,
-	runtime = "rt/bbct",
-	asmext = ".asm",
-	binext = ".bbctiny",
-	tester = tubeemutest,
-}
-
-toolchain_bbct6502 = {
-	name = "bbct6502",
-	cowfe = "bin/cowfe-6502.nncgen.exe",
-	cowbe = "bin/cowbe-6502.nncgen.exe",
-	linker = "bin/cowlink-bbct.nncgen.exe",
-	assembler = buildtass64,
-	runtime = "rt/bbct",
-	asmext = ".asm",
-	binext = ".bbct6502",
-	tester = tubeemutest,
-	archs = { "8080" },
-}
-
-toolchain_unixv7 = {
-	name = "unixv7",
-	cowfe = "bin/cowfe-pdp11.nncgen.exe",
-	cowbe = "bin/cowbe-pdp11.nncgen.exe",
-	linker = "bin/cowlink-v7unix.nncgen.exe",
-	assembler = buildcowasmpdp11,
-	runtime = "rt/unixv7",
-	asmext = ".asm",
-	binext = ".exe",
-	tester = apouttest
-}
-
-toolchain_fuzix6303 = {
-	name = "fuzix6303",
-	cowfe = "bin/cowfe-16bit.nncgen.exe",
-	cowbe = "bin/cowbe-6303.nncgen.exe",
-	linker = "bin/cowlink-fuzix6303.nncgen.exe",
-	assembler = buildcowasm6303,
-	runtime = "rt/fuzix6303",
-	asmext = ".asm",
-	binext = ".6303.exe",
-	tester = fuzix6303test,
-}
-
-toolchain_msdos = {
-	name = "msdos",
-	cowfe = "bin/cowfe-16bit.nncgen.exe",
-	cowbe = "bin/cowbe-8086.nncgen.exe",
-	linker = "bin/cowlink-msdos.nncgen.exe",
-	assembler = buildnasm,
-	runtime = "rt/msdos",
-	asmext = ".asm",
-	binext = ".msdos.exe",
-	tester = emu2test,
-}
-
-ALL_TOOLCHAINS = {}
-addto(ALL_TOOLCHAINS, toolchain_nncgen)
-addto(ALL_TOOLCHAINS, toolchain_ncgen)
-
-addto(ALL_TOOLCHAINS, toolchain_bbct)
-addto(ALL_TOOLCHAINS, toolchain_bbct6502)
-addto(ALL_TOOLCHAINS, toolchain_bbcti)
-addto(ALL_TOOLCHAINS, toolchain_bbctiny)
-addto(ALL_TOOLCHAINS, toolchain_fuzix6303)
-addto(ALL_TOOLCHAINS, toolchain_ncpm)
-addto(ALL_TOOLCHAINS, toolchain_ncpmz)
-addto(ALL_TOOLCHAINS, toolchain_unixv7)
-
-if WITH_ATARITOS then addto(ALL_TOOLCHAINS, toolchain_ataritos) end
-if WITH_LX386    then addto(ALL_TOOLCHAINS, toolchain_lx386) end
-if WITH_LX68K    then addto(ALL_TOOLCHAINS, toolchain_lx68k) end
-if WITH_LXPPC    then addto(ALL_TOOLCHAINS, toolchain_lxppc) end
-if WITH_LXTHUMB2 then addto(ALL_TOOLCHAINS, toolchain_lxthumb2) end
-if WITH_MSDOS    then addto(ALL_TOOLCHAINS, toolchain_msdos) end
-
diff --git a/tools/ataritosemu/build.lua b/tools/ataritosemu/build.lua
deleted file mode 100644
index d4e94e68..00000000
--- a/tools/ataritosemu/build.lua
+++ /dev/null
@@ -1,17 +0,0 @@
-musashilib {
-	m68kconf = "tools/ataritosemu/m68kconf.h",
-	outs = { "$OBJ/tools/ataritosemu/libmusashi.a" }
-}
-
-cprogram {
-	ins = {
-		"tools/ataritosemu/gemdos.c",
-		"tools/ataritosemu/sim.c",
-		"tools/ataritosemu/sim.h",
-		"third_party/musashi/m68k.h",
-		"$OBJ/tools/ataritosemu/libmusashi.a",
-	},
-	outs = { "bin/ataritosemu" },
-}
-
-
diff --git a/tools/ataritosemu/build.py b/tools/ataritosemu/build.py
new file mode 100644
index 00000000..78c29574
--- /dev/null
+++ b/tools/ataritosemu/build.py
@@ -0,0 +1,18 @@
+from build.c import cprogram
+from third_party.musashi.build import musashilib
+
+musashilib(
+    name="musashi",
+    m68kconf="tools/ataritosemu/m68kconf.h",
+)
+
+cprogram(
+    name="ataritosemu",
+    srcs=[
+        "./gemdos.c",
+        "./sim.c",
+        "./sim.h",
+        "third_party/musashi/m68k.h",
+    ],
+    deps=["+musashi"],
+)
diff --git a/tools/build.lua b/tools/build.lua
deleted file mode 100644
index 04c2e0fd..00000000
--- a/tools/build.lua
+++ /dev/null
@@ -1,39 +0,0 @@
-function objectify(e)
-	rule {
-		ins = concat {
-			"tools/objectify",
-			e.ins
-		},
-		outs = e.outs,
-		cmd = "$LUA @1 "..e.symbol.." < @2 > &1"
-	}
-end
-
-cprogram {
-	ins = { "tools/mkadfs.c" },
-	outs = { "bin/mkadfs" },
-}
-
-cprogram {
-	ins = { "tools/mkdfs.c" },
-	outs = { "bin/mkdfs" },
-}
-
-function mkdfs(e)
-	local ins = {}
-	for _, f in ipairs(e.ins) do
-		if not f:find("^-") then
-			ins[#ins+1] = f
-		end
-	end
-
-	rule {
-		ins = concat {
-			"bin/mkdfs",
-			ins,
-		},
-		outs = e.outs,
-		cmd = "@1 -O &1 "..table.concat(e.ins, " ")
-	}
-end
-
diff --git a/tools/build.py b/tools/build.py
new file mode 100644
index 00000000..ed05a9ac
--- /dev/null
+++ b/tools/build.py
@@ -0,0 +1,54 @@
+from build.c import cprogram
+from build.ab2 import Rule, Target, Targets, normalrule, flatten, filenamesof
+
+cprogram(
+    name="mkadfs",
+    srcs=["./mkadfs.c"],
+)
+
+cprogram(
+    name="mkdfs",
+    srcs=["./mkdfs.c"],
+)
+
+
+@Rule
+def objectify(self, name, src: Target = None, symbol=None):
+    normalrule(
+        replaces=self,
+        ins=["tools/objectify", src],
+        outs=[symbol + ".c"],
+        commands=["lua {ins[0]} " + symbol + " < {ins[1]} > {outs}"],
+        label="OBJECTIFY",
+    )
+
+
+@Rule
+def tocpm(self, name, src: Target = None):
+    normalrule(
+        replaces=self,
+        ins=["tools/tocpm.lua", src],
+        outs=[self.localname + ".txt"],
+        commands=["lua {ins[0]} < {ins[1]} > {outs}"],
+        label="TOCPM",
+    )
+
+
+@Rule
+def mkdfs(self, name, flags=[]):
+    srcs = []
+    cmdline = ["{ins[0]}", "-O", "{outs}"]
+    for f in flatten(flags):
+        if isinstance(f, Target):
+            srcs += [f.convert(self)]
+            cmdline += filenamesof(f.convert(self))
+        else:
+            cmdline += [f]
+
+    normalrule(
+        replaces=self,
+        ins=["tools+mkdfs"] + srcs,
+        outs=[self.localname + ".ssd"],
+        commands=[" ".join(cmdline)],
+        label="MKDFS",
+    )
diff --git a/tools/cpmemu/build.lua b/tools/cpmemu/build.lua
deleted file mode 100644
index 574b584d..00000000
--- a/tools/cpmemu/build.lua
+++ /dev/null
@@ -1,24 +0,0 @@
-zmac {
-	ins = { "tools/cpmemu/biosbdos.z80" },
-	outs = { "$OBJ/tools/cpmemu/biosbdos.cim" }
-}
-
-objectify {
-	ins = { "$OBJ/tools/cpmemu/biosbdos.cim" },
-	outs = { "$OBJ/tools/cpmemu/biosbdosdata.c" },
-	symbol = "biosbdosdata"
-}
-
-cprogram {
-	ins = {
-		"tools/cpmemu/main.c",
-		"tools/cpmemu/emulator.c",
-		"tools/cpmemu/fileio.c",
-		"tools/cpmemu/biosbdos.c",
-		"$OBJ/tools/cpmemu/biosbdosdata.c",
-	},
-	ldflags = "-lz80ex -lz80ex_dasm -lreadline",
-	outs = { "bin/cpmemu" }
-}
-
-
diff --git a/tools/cpmemu/build.py b/tools/cpmemu/build.py
new file mode 100644
index 00000000..0fcb8888
--- /dev/null
+++ b/tools/cpmemu/build.py
@@ -0,0 +1,19 @@
+from build.c import cprogram
+from third_party.zmac.build import zmac
+from tools.build import objectify
+
+zmac(name="biosbdos", srcs=["./biosbdos.z80"])
+
+objectify(name="biosbdosdata", src="+biosbdos", symbol="biosbdosdata")
+
+cprogram(
+    name="cpmemu",
+    srcs=[
+        "./main.c",
+        "./emulator.c",
+        "./fileio.c",
+        "./biosbdos.c",
+        "+biosbdosdata",
+    ],
+    vars={"+ldflags": ["-lz80ex", "-lz80ex_dasm", "-lreadline"]},
+)
diff --git a/tools/fuzix6303emu/build.lua b/tools/fuzix6303emu/build.lua
deleted file mode 100644
index 407a7005..00000000
--- a/tools/fuzix6303emu/build.lua
+++ /dev/null
@@ -1,15 +0,0 @@
-cprogram {
-	ins = {
-		"tools/fuzix6303emu/main.c",
-		"tools/fuzix6303emu/disasm.c",
-		"tools/fuzix6303emu/globals.h",
-		"third_party/rc2014emu/6800.c",
-		"third_party/rc2014emu/6800.h",
-	},
-	outs = { "bin/fuzix6303emu" },
-	ldflags = "-lreadline",
-}
-
-
-
-
diff --git a/tools/fuzix6303emu/build.py b/tools/fuzix6303emu/build.py
new file mode 100644
index 00000000..ec38bc68
--- /dev/null
+++ b/tools/fuzix6303emu/build.py
@@ -0,0 +1,12 @@
+from build.c import cprogram
+
+cprogram(
+    name="fuzix6303emu",
+    srcs=[
+        "./main.c",
+        "./disasm.c",
+        "./globals.h",
+    ],
+    deps=["third_party/rc2014emu"],
+    vars={"+ldflags": ["-lreadline"]},
+)
diff --git a/tools/lx68kemu/build.lua b/tools/lx68kemu/build.lua
deleted file mode 100644
index cc6ed12b..00000000
--- a/tools/lx68kemu/build.lua
+++ /dev/null
@@ -1,16 +0,0 @@
-musashilib {
-	m68kconf = "tools/lx68kemu/m68kconf.h",
-	outs = { "$OBJ/tools/lx68kemu/libmusashi.a" }
-}
-
-cprogram {
-	ins = {
-		"tools/lx68kemu/sim.c",
-		"tools/lx68kemu/sim.h",
-		"third_party/musashi/m68k.h",
-		"$OBJ/tools/lx68kemu/libmusashi.a",
-	},
-	outs = { "bin/lx68kemu" },
-}
-
-
diff --git a/tools/lx68kemu/build.py b/tools/lx68kemu/build.py
new file mode 100644
index 00000000..85db496d
--- /dev/null
+++ b/tools/lx68kemu/build.py
@@ -0,0 +1,17 @@
+from build.c import cprogram
+from third_party.musashi.build import musashilib
+
+musashilib(
+    name="musashi",
+    m68kconf="tools/lx68kemu/m68kconf.h",
+)
+
+cprogram(
+    name="lx68kemu",
+    srcs=[
+        "./sim.c",
+        "./sim.h",
+        "third_party/musashi/m68k.h",
+    ],
+    deps=["+musashi"],
+)
diff --git a/tools/newgen/build.lua b/tools/newgen/build.lua
deleted file mode 100644
index 6af30971..00000000
--- a/tools/newgen/build.lua
+++ /dev/null
@@ -1,48 +0,0 @@
-lemon {
-	ins = { "tools/newgen/parser.y" },
-	outs = {
-		"$OBJ/tools/newgen/parser.c",
-		"$OBJ/tools/newgen/parser.h",
-	}
-}
-
-flex {
-	ins = { "tools/newgen/lexer.l" },
-	outs = { "$OBJ/tools/newgen/lexer.c" },
-}
-
-cprogram {
-	ins = {
-		"tools/newgen/main.c",
-		"tools/newgen/utils.c",
-		"tools/newgen/globals.h",
-		"$OBJ/iburgcodes-coh.h",
-		"$OBJ/tools/newgen/parser.c",
-		"$OBJ/tools/newgen/parser.h",
-		"$OBJ/tools/newgen/lexer.c",
-	},
-	objdir = "$OBJ/newgen-cowgol",
-	cflags = "-DCOWGOL",
-	ldflags = "-lfl",
-	outs = { "bin/newgen-cowgol" }
-}
-
-function newgencowgol(e)
-	local infile = e.ins[1]
-	local cppfile = infile:ext(".i"):obj();
-
-	gpp {
-		ins = e.ins,
-		outs = { cppfile }
-	}
-
-	rule {
-		ins = concat {
-			"bin/newgen-cowgol",
-			cppfile
-		},
-		outs = e.outs,
-		cmd = "@1 @2 &1 &2"
-	}
-end
-
diff --git a/tools/newgen/build.py b/tools/newgen/build.py
new file mode 100644
index 00000000..0ef8c248
--- /dev/null
+++ b/tools/newgen/build.py
@@ -0,0 +1,35 @@
+from build.ab2 import Rule, Targets, normalrule
+from build.c import cprogram
+from build.yacc import flex
+from build.gpp import gpp
+from third_party.lemon.build import lemon
+
+lemon(name="parser", src="./parser.y")
+
+flex(name="lexer", srcs=["./lexer.l"])
+
+cprogram(
+    name="newgen",
+    srcs=[
+        "./main.c",
+        "./utils.c",
+        "./globals.h",
+        "+parser",
+        "+lexer",
+        "src+iburgcodes",
+    ],
+    vars={"+cflags": ["-DCOWGOL"], "+ldflags": ["-lfl"]},
+)
+
+
+@Rule
+def newgencowgol(self, name, srcs: Targets = []):
+    preprocessed = gpp(name=name + "/preprocessed", srcs=srcs)
+
+    normalrule(
+        replaces=self,
+        ins=["tools/newgen", preprocessed],
+        outs=["inssel.coh", "inssel.decl.coh"],
+        commands=["{ins[0]} {ins[1]} {outs[0]} {outs[1]}"],
+        label="NEWGEN",
+    )
diff --git a/tools/obpemu/build.lua b/tools/obpemu/build.lua
deleted file mode 100644
index 4f53f951..00000000
--- a/tools/obpemu/build.lua
+++ /dev/null
@@ -1,12 +0,0 @@
-cprogram {
-	ins = {
-		"tools/obpemu/main.c",
-		"tools/obpemu/emulator.c",
-	},
-	outs = { "bin/obpemu" },
-	ldflags = "-lreadline",
-}
-
-
-
-
diff --git a/tools/obpemu/build.py b/tools/obpemu/build.py
new file mode 100644
index 00000000..78c9d0c9
--- /dev/null
+++ b/tools/obpemu/build.py
@@ -0,0 +1,7 @@
+from build.c import cprogram
+
+cprogram(
+    name="obpemu",
+    srcs=["./emulator.c", "./main.c"],
+    vars={"+ldflags": "-lreadline"},
+)
diff --git a/dist/cpm/tocpm.lua b/tools/tocpm.lua
similarity index 100%
rename from dist/cpm/tocpm.lua
rename to tools/tocpm.lua
diff --git a/tools/tubeemu/build.lua b/tools/tubeemu/build.lua
deleted file mode 100644
index 0789c66a..00000000
--- a/tools/tubeemu/build.lua
+++ /dev/null
@@ -1,11 +0,0 @@
-cprogram {
-	ins = {
-		"tools/tubeemu/bbctube.c",
-		"third_party/lib6502/lib6502.c",
-		"third_party/lib6502/lib6502.h",
-	},
-	outs = { "bin/tubeemu" }
-}
-
-
-
diff --git a/tools/tubeemu/build.py b/tools/tubeemu/build.py
new file mode 100644
index 00000000..fee3995f
--- /dev/null
+++ b/tools/tubeemu/build.py
@@ -0,0 +1,3 @@
+from build.c import cprogram
+
+cprogram(name="tubeemu", srcs=["./bbctube.c"], deps=["third_party/lib6502"])