kwmu4k / uni04

silly little 4-bit arch :3

uni04

uni04 (or uni.4) is a 4-bit architecture made for Alex's 4-bit arch challenge

There are 2 registers, X (accumulator), and Y

  v ALU
┌──┬─┐
│  │ │ <- Registers
│  │ │
├──┴─┤
└────┘
  ^ Control Unit

Instructions

Opcode	Instruction	Arguments	Description
00	imm	reg con	Immediate value
01	ldx	adr	Load adr into X
02	ldy	adr	Load adr into Y
03	ldi	reg adr reg	Indexed load
04	stx	adr	Store X into adr
05	sty	adr	Store Y into adr
06	mov	reg reg	Move value from reg1 to reg2
07	add	reg reg	reg1 += reg2
08	sub	reg reg	reg1 -= reg2
09	shr	reg con	Shift right reg by con
0A	not	reg	Bitwise NOT on reg
0B	nor	reg con	Bitwise NOR on reg by con
0C	jmp	adr	Jump to adr
0D	jmz	adr	Jump to adr if zero
0E	cal	adr	Call subroutine
0F	ret		Return from subroutine

ASM syntax example

mov x y    // Hmmm comment
ldx 7      // meow :3
ldi x 21 a

As you can see instead of ; you use // and there is no , unlike most ASMs

Turning into opcode

Registers

x	0
y	1

mov x y = 06 00 01

imm x 8 = 00 00 08

Addreses (8-bit)

adr	##

ldx 16 = 01 0F

jmz 27 = 0D 1B

Constants

con	#

nor x 1 = 0B 01 01