256‑bit Virtual Computer open source

Word size: 256-bit Registers: 8 (R0..R7) Memory: 4096 words

Program Editor (Assembly-like)

CPU State

0
Z=0 N=0 C=0
Ready
Registers (hex)
RegHex (64 nybbles)
Watch Memory (addresses are word-indexed)
0x0

I/O Console

Architecture & Instruction Set

256-bit unsigned (mod 2^256 arithmetic)
R0..R7 (general purpose)
Z (zero), N (sign bit), C (carry on add/sub)
4096 words (256-bit), addressed by word index
Comments start with ; or # · Labels end with : · Hex immediates with 0x · Decimal otherwise.
LI Rn, imm · Load immediate
MOVE Rd, Rs
LOAD Rd, [Ra+off] · off optional
STORE Rs, [Ra+off]
ADD|SUB|MUL|DIV|AND|OR|XOR Rd, Ra, Rb
NOT Rd, Ra
SHL|SHR Rd, Ra, imm
CMP Ra, Rb · sets Z,N
JMP label | JZ label | JNZ label
OUT Rs · low 8-bit as char · OUTN Rs · print decimal
IN Rd · prompt for decimal · HALT
Hackable VM Core (edit & Apply)
(You can modify the CPU step() and helpers below and click Apply.)