Build a CPU out of logic gate in TypeScript

It's romantic (meaning waste of time).

How to play with it

pnpm install
cd packages/playground
pnpm exec vite

Then open the console.

Use tick() to create a clock cycle.

Description

• 16-bits CPU. It's working.
• Up to 64KB RAM.
• 4 general purpose register. (can expand the number of them easily).
• Variable instruction cycle. (from 2 to ...)
• Variable machine code length. (from 2 to ...)

Instructions

Current it can do:

• Copy data between immediate/register/memery
• Add/Substract
• Halt and do nothing
• Jump, w/ condition
• Stack (push,pop)
• Call/return

Layout

• 2*n bytes
• 1st byte : instruction
  • 1st bit: 8 bit mode (for instructions involving immediate/memory address)
• 2nd byte : register address
  • 1st 4-bits is destination, followed by 4-bits source.
  • Reg A: 0b0001
  • Reg B: 0b0010
• others: immediate

Some instructions don't require register information (like JMP), so 2nd byte is not needed (directly followed by imm.)

References

• HALT

  0b00001111

• NOP

  0b00011011

• MOV reg imm (from imm. to register)

  0b00001000,<register-addr>,<immediate-l>,<immediate-h>
  0b10001000,<register-addr>,<immediate-l>

• MOV dst src (from register to register)

  0b00001001,<register-addr>
  0b10001001,<register-addr>

• MOV reg mem

  0b00001010,<register-addr>,<addr-l>,<addr-h>
  0b10001010,<register-addr>,<addr-l>,<addr-h>

• MOV mem reg

  0b00001011,<register-addr>,<addr-l>,<addr-h>
  0b10001011,<register-addr>,<addr-l>,<addr-h>

• ADD dst src : add accumulator (A register) with [source] (register) and store the result in [dest] (register)

  0b00000100,<register-addr>
  0b10000100,<register-addr>

• SUB dst src : substract: similar to add.

  0b00000101,<register-addr>
  0b10000101,<register-addr>

• INC dst src

  0b00001100,<register-addr>

• DEC dst src

  0b00001101,<register-addr>

• JMP : unconditional jump

  0b00010100,<addr-l>,<addr-h>

• JZ : jump if zero

  0b00010110,<addr-l>,<addr-h>

  Flag zero: Avaliable after ADD/SUB/INC/DEC

• JNZ : jump if not zero

  0b00010111,<addr-l>,<addr-h>

• CALL reg

  0b00011000,<0000|source-register-addr>

• RET

  0b00011001

• PUSH reg

  0b00001101,<0000|source-register-addr>
  0b10001101,<0000|source-register-addr>

• POP reg

  0b00001101,<dest-register-addr|0000>
  0b10001101,<dest-register-addr|0000>

CALL/RET

TODO

• More instructions
  • ALU related
• Interrupt
  • Keyboard
  • Timer
• A display (that's why I'm testing in browser)