This repository contains my version of a little man computer but for the cie a level instruction set. It is hosted here.
these are all the possible instructions:
Possible operands:
#n: a number either in denary as#123, binary as#B1010, or hex as#&FE<address>: an address of memory in the little man computer<register>: a register in the little man computer. Allowed registers are specified in the description- nothing: no operand
| Instruction | Operand | Description |
|---|---|---|
| END | Return control to the operating system | |
| LDM | #n |
Immediate addressing. Load the number n to ACC |
| LDD | <address> |
Direct addressing. Load the contents of the location at the given address to ACC |
| LDI | <address> |
Indirect addressing. The address to be used is at the given address. Load the contents of this second address to ACC |
| LDX | <address> |
Indexed addressing. Form the address from <address> + the contents of the index register. Copy the contents of this calculated address to ACC |
| LDR | #n |
Immediate addressing. Load the number n to IX |
| MOV | <register> |
Move the contents of the accumulator to the given register (IX) |
| STO | <address> |
Store the contents of ACC at the given address |
| ADD | <address> |
Add the contents of the given address to the ACC |
#n |
Add the number n to the ACC | |
| SUB | <address> |
Subtract the contents of the given address from the ACC |
#n |
Subtract the number n from the ACC | |
| INC | <register> |
Add 1 to the contents of the register (ACC or IX) |
| DEC | <register> |
Subtract 1 from the contents of the register (ACC or IX) |
| JMP | <address> |
Jump to the given address |
| CMP | <address> |
Compare the contents of ACC with the contents of <address> |
#n |
Compare the contents of ACC with number n | |
| CMI | <address> |
Indirect addressing. The address to be used is at the given address. Compare the contents of ACC with the contents of this second address |
| JPE | <address> |
Following a compare instruction, jump to <address> if the compare was True |
| JPN | <address> |
Following a compare instruction, jump to <address> if the compare was False |
| IN | Key in a character and store its ASCII value in ACC. Defaults to 0 if no character is entered | |
| OUT | Output to the screen the character whose ASCII value is stored in ACC | |
| LSL | #n |
Bits in ACC are shifted logically n places to the left. Zeros are introduced on the right-hand end |
| LSR | #n |
Bits in ACC are shifted logically n places to the right. Zeros are introduced on the left-hand end |
| AND | <address> |
Bitwise AND operation of the contents of ACC with the contents of <address> |
#n |
Bitwise AND operation of the contents of ACC with the operand | |
| OR | <address> |
Bitwise OR operation of the contents of ACC with the contents of <address> |
#n |
Bitwise OR operation of the contents of ACC with the operand | |
| XOR | <address> |
Bitwise XOR operation of the contents of ACC with the contents of <address> |
#n |
Bitwise XOR operation of the contents of ACC with the operand | |
| BRK | NON STANDARD INSTRUCTION. adds a breakpoint in the browser console and dumps the current memory into the browser console | |
| ERR | #n |
NON STANDARD INSTRUCTION. Errors with error code #n |