vc4

virtual computer 4 (see vc3 and vc2)

a computer-emulator with custom architecture, and some stuff to write and run software on it.

goals

assemble program on host
run program from host
run program from emulated disk
output to monitor device
input from keyboard device
command shell
read/write files on emulated disk
host/vm file share
run programs from emulated disk
edit text files
assemble program on vm

isa

16-bit instruction set
big endian

registers

r0      accumulator / return value
r1
r2
r3
r4
r5
r6
sp      stack pointer
bp      base pointer

instructions

r   = register
i16 = 16-bit immediate
m   = memory [r/i16]

nop
hlt
jmp     r/i16
jnz     r/i16
cmp     r/i16
mov     r/i16/m r
mov     r       r/i16/m
movb    m       r
movb    r       m
in      r/i16
out     r/i16   r/i16
call    r/i16
ret
lit     r/i16
int     i8

or      r       r/i16
xor     r       r/i16
and     r       r/i16
shl     r       r/i16
rshl    r       r/i16
shr     r       r/i16
rshr    r       r/i16
add     r       r/i16
sub     r       r/i16
rsub    r       r/i16
mul     r       r/i16
imul    r       r/i16
div     r       r/i16
idiv    r       r/i16
mod     r       r/i16
rmod    r       r/i16