CPU is programmable.
CPU is a hardware which is controlled by easy-to-modify software.
Couple more instructions for CPU:
| Instruction | Description |
|---|---|
| SUB (Subtract) | Subtract two registers, store value into second registers. |
| JUMP | Update instruction address register to new address. |
| JUMP_NEG (Jump Negative) | If ALU result was negative, update instruction address register to new address. |
| HALT | Program done. Halt computer. |
- Other instructions :
JUMP_IF_EQUAL,JUMP_IF_GREATER, ...
- Software allows jobs that hardware can't do - ex) division.
- Modern processors have thousand instructions.
Thoughts
- If 조건문이 CPU 레벨의 JUMP 에서부터 시작되었구나...
배우는 가장 좋은 방법은 가르치는 것이다.