8bit cpu:
- 4 gpr

bus-based interface between component:
- format:
  - 1 value: dest
  - 1 value: source
  - 1 value: command
  - 2 value: operands

fixed size instructions (1-byte each):
- jnz (prefix) 0b000 (offset) 0bXXXXX (5bit signed)
- mov (prefix) 0b0010 (src) 0bXX (dst) 0bXX
- swp (prefix) 0b0011 (src) 0bXX (dst) 0bXX
- shl (prefix) 0b010 (src) 0bXX (sh) 0bXXX
- shr (prefix) 0b011 (src) 0bXX (sh) 0bXXX
- add (prefix) 0b1000 (src) 0bXX (dst) 0bXX
- sub (prefix) 0b1001 (src) 0bXX (dst) 0bXX
- xor (prefix) 0b1010 (src) 0bXX (dst) 0bXX
- and (prefix) 0b1011 (src) 0bXX (dst) 0bXX
- ldb (prefix) 0b1100 (reg-addr) 0bXX (reg-dst) 0bXX
- stb (prefix) 0b1101 (reg-src) 0bXX (reg-addr) 0bXX
- inp (prefix) 0b111000 (dst) 0bXX
- out (prefix) 0b111001 (src) 0bXX
- not (prefix) 0b111010 (reg) 0bXX
- jre (prefix) 0b111011 (reg) 0bXX
- inc (prefix) 0b111100 (reg) 0bXX
- dec (prefix) 0b111101 (reg) 0bXX
- hlt (prefix) 0b11111111

program:
- read input into memory,
- compute some checksum over values
- validate checksum

description:
- pff password managers, I store secrets in a TPM! (tesselated platform module)
- run with 'echo -ne "SECRET\x00" | ./tis256 chall.asm'

credit the artist:
https://www.pixilart.com/art/bongo-cat-8c9e158c184a944