tomlister / virtualcpu

virtualcpu

A very basic virtual computer.

You can write ascii to the video memory address 0xb8 and it will print to the screen.

VASM

mov ax, 0xb8
mov [ax], 0x48
inc ax
mov [ax], 0x65
inc ax
mov [ax], 0x79

Machine Code

01E0B801 D0E0D048 02E001D0 E0D06502 E001D0E0 D079

VGA Output:

Hey

Current Instruction Set

• mov -- move
• inc -- increment

Next Revision's Instruction Set

• mov -- move
• inc -- increment
• db -- define byte
• equ -- assign values to symbols
• cmp -- compare
• jne -- jump if not equal