VIA C3

From Misc Data Digs

Alternate Instruction Set[edit | edit source]

By executing the x86 instruction 0x0F3F, it will enable the VIA C3's internal registers and instruction set. Some of these processors also came with the instruction set enabled.

Known instructions include:

Instruction Name Effect
lgd load base address of gdt into register
mov copy register contents
izx load 2 byte immediate, zero extended
isx load 2 byte immediate, sign extended
ra4 shift eax (r0) right by 4
la4 shift eax (r0) left by 4
ra8 shift eax (r0) right by 8
la8 shift eax (r0) left by 8
and bitwise and of two registers, into eax
or bitwise or of two registers, into eax
ada add register to eax
sba sub register from eax
ld4 load 4 bytes from kernel memory
st4 store 4 bytes into kernel memory
ad4 increment a register by 4
ad2 increment a register by 2
ad1 increment a register by 1
zl3 zero low 3 bytes of register
zl2 zero low 2 bytes of register
zl1 zero low byte of register
cmb shift lo word of source into lo word of destination

(Source: xoreaxeaxeax's RosenBridge GitHub repo)