Sacred Tongue ISA v0

Last updated: February 19, 2026 Status: Prototype ISA for STVM Phase-1

Scope

This is the bootstrap ISA for Sacred Tongue VM. It does not claim full 1,536 semantic ops yet. It defines a deterministic executable subset.

Opcode Space

• Tongues: 6 (KO, CA, RU, AV, DR, UM)
• Per-tongue opcode byte: 0..255
• Total addressable instruction heads: 6 * 256 = 1536
• Implemented in v0: 29 instructions

Instruction Encoding

Fixed-width 8-byte instruction:

byte 0: tongue_id   (KO=0, CA=1, RU=2, AV=3, DR=4, UM=5)
byte 1: opcode      (0..255)
byte 2: a           (u8)
byte 3: b           (u8)
byte 4..7: imm      (i32 little-endian)

Container format (STV1):

offset 0..3:  magic = "STV1"
offset 4..7:  instruction_count (u32 LE)
offset 8.. :  instruction stream (count * 8 bytes)

Register File

• r0..r20 (21 registers, integer semantics in v0)

Tongue Families (v0)

KO Control Flow

• KO.NOP 0x00
• KO.HALT 0x01
• KO.JMP target 0x02
• KO.JZ reg target 0x03
• KO.JNZ reg target 0x04
• KO.CALL target 0x05
• KO.RET 0x06
• KO.YIELD 0x07

CA Arithmetic and Logic

• CA.MOVI reg imm 0x10
• CA.MOV dst src 0x11
• CA.ADD dst src 0x12
• CA.SUB dst src 0x13
• CA.MUL dst src 0x14
• CA.DIV dst src 0x15
• CA.MOD dst src 0x16
• CA.CMP lhs rhs 0x17
• CA.AND dst src 0x18
• CA.OR dst src 0x19
• CA.XOR dst src 0x1A

RU Memory

• RU.LOAD reg addr 0x20
• RU.STORE reg addr 0x21

AV IPC and Syscalls

• AV.SEND reg channel 0x30
• AV.RECV reg channel 0x31
• AV.SYSCALL id 0x32

DR Validation

• DR.ASSERT reg 0x40
• DR.VERIFY reg 0x41

UM Security Ops

• UM.HASH reg 0x50
• UM.REDACT reg 0x51

Sacred Token Heads

Instruction heads can be authored as:

• mnemonic: KO.JMP
• sacred token form: ko:<prefix>'<suffix>

stasm decodes sacred token heads using packages/sixtongues/sixtongues.py.

Example

Assembly:

start:
  CA.MOVI r0 2
  CA.MOVI r1 3
  CA.ADD r0 r1
  AV.SEND r0 1
  KO.HALT

Build and run:

python scripts/stasm.py examples/stvm/hello_world.sta -o examples/stvm/hello_world.stv --listing
python scripts/stvm.py run examples/stvm/hello_world.stv

Out of Scope in v0

• Floating-point ops
• Vectorized PHDM register ops
• Privilege ring enforcement in interpreter core
• Syscall ABI and host HAL
• JIT/AOT backends