Instruction Reference

This chapter is the compact reference. Come here when you know what you want to do and just need the exact instruction.

Data movement

Mnemonic	Bytes	Meaning	Effect
`LDA`	1	Load from memory	`A = mem[DP]`
`STA`	1	Store to memory	`mem[DP] = A`
`LDI imm8`	2	Load immediate into `A`	`A = imm`
`LDP imm16/label`	3	Load immediate into `DP`	`DP = addr`
`LDL`	1	Set low byte of `DP` from `A`	`DP[7:0] = A`
`LDH`	1	Set high byte of `DP` from `A`	`DP[15:8] = A`
`SDL`	1	Read low byte of `DP` into `A`	`A = DP[7:0]`
`SDH`	1	Read high byte of `DP` into `A`	`A = DP[15:8]`
`IDP`	1	Increment `DP`	`DP = DP + 1`
`DDP`	1	Decrement `DP`	`DP = DP - 1`

Mnemonic	Bytes	Meaning	Effect
`ADD`	1	Add memory to `A`	`A = A + mem[DP]`
`SUB`	1	Subtract memory from `A`	`A = A - mem[DP]`
`CMP`	1	Compare `A` with memory	flags from `A - mem[DP]`
`ADI imm8`	2	Add immediate	`A = A + imm`
`SBI imm8`	2	Subtract immediate	`A = A - imm`
`CMI imm8`	2	Compare immediate	flags from `A - imm`

These instructions update flags except for store-like operations.

Mnemonic	Bytes	Meaning	Effect
`AND`	1	Bitwise AND	`A = A & mem[DP]`
`ORR`	1	Bitwise OR	`A = A \| mem[DP]`
`XOR`	1	Bitwise XOR	`A = A ^ mem[DP]`
`SHL`	1	Shift left	`A = A << 1`
`SHR`	1	Shift right	`A = A >> 1`

Mnemonic	Bytes	Meaning	Effect
`PSH`	1	Push `A`	`push(A)`
`POP`	1	Pop into `A`	`A = pop()`
`JSR addr`	3	Jump to subroutine	`push(PC); PC = addr`
`RET`	1	Return	`PC = pop()`

Mnemonic	Bytes	Meaning	Effect
`JMP addr`	3	Unconditional jump	`PC = addr`
`JEQ addr`	3	Jump if zero	if `Z`, jump
`JNG addr`	3	Jump if negative	if `N`, jump
`NOP`	1	Do nothing	no state change
`HLT`	1	Halt execution	stop VM

Mnemonic	Bytes	Meaning	Effect
`PRT`	1	Print byte in `A`	output `A`
`RTR`	1	Read byte into `A`	`A = read()`

T32 maintains:

In practice, this means you often compute or compare first, then branch.