@value // A = value
where value is either a constant or a symbol referring to such a constant
Binary syntax: 0valueInBinary
- eg: @21 will be translated to 0000000000010101
- Variable symbols: represent memory locations where the programmer wants to maintain values
- Label symbols: represent destinations of goto instructions
- Pre-defined symbols: represent special memory locations
- In the Hack programming language, there are 23 pre-defined symbols
dest = comp ; jump (both dest and jump are optional)
Binary syntax: 1 1 1 a c1 c2 c3 c4 c5 c6 d1 d2 d3 j1 j2 j3
| comp | comp | c1 c2 c3 c4 c5 c6 |
|---|---|---|
| 0 | 101010 | |
| 1 | 111111 | |
| -1 | 111010 | |
| D | 001100 | |
| A | M | 110000 |
| !D | 001111 | |
| !A | !M | 110001 |
| -D | 001111 | |
| -A | -M | 110011 |
| D + 1 | 011111 | |
| A + 1 | M + 1 | 110111 |
| D - 1 | 001110 | |
| A - 1 | M - 1 | 110010 |
| D + A | D + M | 000010 |
| D - A | D - M | 010011 |
| A - D | M - D | 000111 |
| D & A | D & M | 000000 |
| D | A | D | M | 010101 |
| a = 0 | a = 1 |
| dest | d1 d2 d3 | effect: the value is stored in |
|---|---|---|
| null | 000 | The value is not stored |
| M | 001 | RAM[A] |
| D | 010 | D register |
| MD | 011 | RAM[A] and D register |
| A | 100 | A register |
| AM | 101 | A register and RAM[A] |
| AD | 110 | A register and D register |
| AMD | 111 | A register, RAM[A] and D register |
| jump | j1 j2 j3 | effect: the value is stored in |
|---|---|---|
| null | 000 | no jump |
| JGT | 001 | if out > 0 jump |
| JEQ | 010 | if out = 0 jump |
| JGE | 011 | if out >= 0 jump |
| JLT | 100 | if out < 0 jump |
| JNE | 101 | if out != 0 jump |
| JLE | 110 | if out <= 0 jump |
| JMP | 111 | Unconditional jump |
- Computes the value of comp
- Stores the result in dest
- If the Boolean expression (comp jump 0) is true, jumps to execute the instruction stored in ROM[A]
- SCREEN: base address of the screen memory map (16,384)
- KBD: address of the keyboard memory map (24,576)
Check out ./Architecture.svg to zoom into details
