Support several ROMs. *BASIC

README.md

@@ -25,6 +25,7 @@ References:
 ## Features
 - Some of the MOS entrypoints and VDU control codes are defined.
 - Can run BBC BASIC and most of the language ROMs.
+- Can load up to 16 sideways ROMs.
 - Saves and loads files from the host filesystem.
 - Does some of the mode 7 text coloring using ANSI escape codes on the terminal. Try `VDU 65,129,66,130,67,132,68,135,69,13,10` on BBC BASIC.
 - OSCLI comands suported:
@@ -39,8 +40,8 @@ References:
 bbz [flags] [filename]
 ```
 
-`filename` is the filename of the ROM to run. With no arguments it
-runs the BBC Basic ROM in `BASIC.ROM`.
+`filename` is the filename of the ROM to run (the same as `-rom0`). By default, it
+uses the BBC Basic ROM in `BASIC.ROM`.
 
 AvaIlable flags (to put before the ROM filename if present):
 
@@ -50,6 +51,40 @@ AvaIlable flags (to put before the ROM filename if present):
   -m	dump to the console the MOS calls excluding console I/O calls
   -p	panic on not implemented MOS calls
   -s	dump to the console the accesses to Fred, Jim or Sheila
+  -rom0 string
+    	filename for rom 0 (slot 0xf)
+  -rom1 string
+    	filename for rom 1 (slot 0xe)
+  -rom2 string
+    	filename for rom 2 (slot 0xd)
+  -rom3 string
+    	filename for rom 3 (slot 0xc)
+  -rom4 string
+    	filename for rom 4 (slot 0xb)
+  -rom5 string
+    	filename for rom 5 (slot 0xa)
+  -rom6 string
+    	filename for rom 6 (slot 0x9)
+  -rom7 string
+    	filename for rom 7 (slot 0x8)
+  -rom8 string
+    	filename for rom 8 (slot 0x7)
+  -rom9 string
+    	filename for rom 9 (slot 0x6)
+  -rom10 string
+    	filename for rom 10 (slot 0x5)
+  -rom11 string
+    	filename for rom 11 (slot 0x4)
+  -rom12 string
+    	filename for rom 12 (slot 0x3)
+  -rom13 string
+    	filename for rom 13 (slot 0x2)
+  -rom14 string
+    	filename for rom 14 (slot 0x1)
+  -rom15 string
+    	filename for rom 15 (slot 0x0)
+
+
 
 ```
 
@@ -108,3 +143,31 @@ Using mode 7 colors:
 
 ![mode 7 colors](doc/vdu_colors.png)
 
+Using several ROMs at once:
+```
+$ go run *.go -rom0 BASIC.ROM -rom1 ROMs/Forth_103.rom -rom2 ROMs/LISP-200.rom -rom3 ROMs/COMAL.rom
+bbz - Acorn MOS for 6502 adaptation layer, https://github.com/ivanizag/bbz
+(tip: uppercase is usually needed)
+
+BASIC - (C)1982 Acorn
+
+>*LISP
+LISP - (C)1982 Acornsoft/1979 Owl Computers
+
+
+Evaluate : (* '*FORTH)
+FORTH - (C) Acornsoft Ltd. 1983
+
+COLD or WARM start (C/W)? C
+
+
+FORTH
+OK
+OS' *COMAL'
+COMAL - (C)Acorn
+→*BASIC
+BASIC - (C)1982 Acorn
+
+>
+
+```

asm/firmware.s

@@ -4,7 +4,7 @@
 
 
 ; constants
-                .exportzp ROM_SELECT := $f4 
+                .exportzp ROM_SELECT := $f4
                 .export ROM_TABLE := $023a
                 .export LANGUAGE_ENTRY := $8000
                 .export SERVICE_ENTRY := $8003
@@ -82,7 +82,7 @@ OSBYTE_143:		lda	ROM_SELECT          ; Get current ROM number
 			    ldx	#$0f                ; Start at ROM 15
 				; Issue service call loop
 NEXT:			inc ROM_TABLE,X         ; Read bit 7 on ROM type table (no ROM has type 254 &FE)
-                dec ROM_TABLE,X         ; 
+                dec ROM_TABLE,X         ;
                 bpl SKIP                ; If not set (+ve result), step to next ROM down
                 stx ROM_SELECT          ; Otherwise, select this ROM, &F4 RAM copy
                 stx ROM_LATCH           ; Page in selected ROM

bbz.go

@@ -12,20 +12,6 @@ import (
 */
 
 func RunMOS(env *environment) {
-
-	/*
-		Next, the MOS will set the error point at &FD/&FE to point at the version string (or copyright
-		message if no version string is present).
-	*/
-	copyrightAddress := 0x8000 + 1 + uint16(env.mem.Peek(romCopyrightOffsetPointer))
-	copyrigt := env.mem.getString(copyrightAddress, 0)
-	env.mem.pokeWord(zpErrorPointer, copyrightAddress)
-	/*
-		The MOS also automatically prints the ROM's title string (&8009) so that the user is acknowledged.
-	*/
-	language := env.mem.getString(romTitleString, 0)
-	fmt.Printf("%s - %s\n", language, copyrigt)
-
 	// Execute
 	for !env.stop {
 		env.cpu.ExecuteInstruction()

environment.go

@@ -60,6 +60,40 @@ func (env *environment) getFile(handle uint8) *os.File {
 	return nil
 }
 
+func (env *environment) initUpperLanguage() {
+	for slot := 0xf; slot >= 0; slot-- {
+		romType := env.mem.data[romTypeTable+uint16(slot)]
+		if romType&0x40 != 0 {
+			env.initLanguage(uint8(slot))
+			return
+		}
+	}
+
+	panic("There is no language ROM available to boot")
+}
+
+func (env *environment) initLanguage(slot uint8) {
+	env.mem.Poke(zpROMSelect, slot)
+	env.mem.Poke(sheila_rom_latch, slot)
+
+	/*
+		Next, the MOS will set the error point at &FD/&FE to point at the version string (or copyright
+		message if no version string is present).
+	*/
+	copyrightAddress := 0x8000 + 1 + uint16(env.mem.Peek(romCopyrightOffsetPointer))
+	copyrigt := env.mem.getString(copyrightAddress, 0)
+	env.mem.pokeWord(zpErrorPointer, copyrightAddress)
+	/*
+		The MOS also automatically prints the ROM's title string (&8009) so that the user is acknowledged.
+	*/
+	language := env.mem.getString(romTitleString, 0)
+	fmt.Printf("%s - %s\n", language, copyrigt)
+
+	_, x, y, p := env.cpu.GetAXYP()
+	env.cpu.SetAXYP(1, x, y, p)
+	env.cpu.SetPC(romStartAddress)
+}
+
 func (env *environment) raiseError(code uint8, msg string) {
 	/*
 		The BBC microcomputer adopts a standard pattern of bytes

main.go

@@ -29,22 +29,26 @@ func main() {
 		"p",
 		false,
 		"panic on not implemented MOS calls")
-	rom0 := flag.String(
-		"rom",
-		"",
-		"filename for rom 0 (slot 0xf)")
-	rom1 := flag.String(
-		"rom1",
-		"",
-		"filename for rom 1 (slot 0xe)")
-	flag.Parse()
 
-	romFile := flag.Arg(0)
-	if *rom0 != "" {
-		romFile = *rom0
+	roms := make([]*string, 16)
+	for i := 0; i < 16; i++ {
+		roms[i] = flag.String(
+			fmt.Sprintf("rom%v", i),
+			"",
+			fmt.Sprintf("filename for rom %v (slot 0x%x)", i, 15-i))
 	}
-	if romFile == "" {
-		romFile = "BASIC.ROM"
+
+	flag.Parse()
+
+	if *roms[0] == "" {
+		romFile := flag.Arg(0)
+		if romFile == "" {
+			def := "BASIC.ROM"
+			roms[0] = &def
+		} else {
+			roms[0] = &romFile
+		}
+
 	}
 
 	env := newEnvironment(*traceCPU,
@@ -54,11 +58,14 @@ func main() {
 		*panicOnErr)
 
 	env.mem.loadFirmware("firmware")
-	env.mem.loadRom(romFile, 0xf)
-	env.mem.Poke(zpROMSelect, 0xf)
-	if *rom1 != "" {
-		env.mem.loadRom(*rom1, 0xe)
+
+	for i, rom := range roms {
+		if *rom != "" {
+			env.mem.loadRom(*rom, uint8(0xf-i))
+		}
 	}
 
+	env.initUpperLanguage()
+
 	RunMOS(env)
 }

osByte.go

@@ -154,6 +154,19 @@ func execOSBYTE(env *environment) {
 		*/
 		// TODO
 
+	case 0x8e:
+		option = "Enter language ROM"
+		/*
+			Entry parameters: X determines which language ROM is entered
+			The selected language will be re-entered after a soft BREAK.
+			The action of this call is to printout the language name and enter the selected
+			language ROM at &8000 with A=1. Locations &FD and &FE in zero page point to the
+			copyright message in the ROM. When a Tube is present this call will copy the
+			language across to the second processor.
+		*/
+		env.initLanguage(x)
+		newA = 1
+
 	case 0xca:
 		option = "Read/write keyboard status byte"
 		/*
@@ -182,6 +195,17 @@ func execOSBYTE(env *environment) {
 			env.notImplemented("OSBYTEda for x or y not zero")
 		}
 
+	case 0xea:
+		option = "R/W Tube present flag"
+		/*
+			The value 255 indicates the Tube is present 0 indicates it is not
+			Writing to this value is not recommended
+
+			We return 0 always
+		*/
+		newX = 0
+		newY = 0
+
 	default:
 		env.notImplemented(fmt.Sprintf("OSBYTE%02x", a))
 		/*

osCLI.go

@@ -24,6 +24,7 @@ func execOSCLI(env *environment) {
 	// The command-line interpreter does not distinguish between upper and lower case characters in the command name
 	command = strings.ToUpper(command)
 	params := fields[1:]
+	handled := false
 
 	if command == "*" && len(params) > 0 {
 		// There are spaces between the * and the command
@@ -61,11 +62,13 @@ func execOSCLI(env *environment) {
 			for example.
 		*/
 		// do nothing
+		handled = true
 
 	case "*H.":
 		fallthrough
 	case "*HELP":
 		msg = "bbz - Acorn MOS for 6502 adaptation layer, https://github.com/ivanizag/bbz"
+		handled = true
 
 		// TODO: multiple ROMS: service call 9 after the MOS message
 
@@ -74,9 +77,11 @@ func execOSCLI(env *environment) {
 	case "*CAT":
 		// TODO
 		msg = "<<directory placeholder>>"
+		handled = true
 
 	case "*QUIT":
 		env.stop = true
+		handled = true
 
 	case "*HOST":
 		if len(params) == 0 {
@@ -89,6 +94,7 @@ func execOSCLI(env *environment) {
 			}
 			fmt.Println(string(stdout))
 		}
+		handled = true
 
 	case "*FX":
 		// Parse  *FX args
@@ -117,14 +123,27 @@ func execOSCLI(env *environment) {
 		// Send to OSBYTE
 		env.cpu.SetAXYP(uint8(argA), uint8(argX), uint8(argY), p)
 		execOSBYTE(env)
+		handled = true
+
+	case "*BASIC":
+		// Runs the first language ROM with no service entry
+		for slot := 0xf; slot >= 0; slot-- {
+			romType := env.mem.data[romTypeTable+uint16(slot)]
+			if romType&0b1100_0000 == 0b0100_0000 { // bit 7 clear, bit 6 set
+				env.initLanguage(uint8(slot))
+				handled = true
+				break
+			}
+		}
+	}
 
-	default:
+	if !handled {
 		// Send to the other ROMS if available.
 		env.mem.pokeWord(zpStr, xy)
 		cmd := uint8(4) // Unrecognized command
 		env.cpu.SetAXYP(cmd, x, 1, p)
 		env.cpu.SetPC(procCLITOROMS)
-		// procCLITOROMS issues a 254-Bad command if the command is not handles by any ROM
+		// procCLITOROMS issues a 254-Bad command if the command is not handled by any ROM
 	}
 
 	if msg != "" {