BOX-256
BOX-256 is a game played by writing assembly code to pass graphics tests.
History
BOX-256 was released for Windows and as an in-browser game by Juha Kiili in April 2016. The first release includes 4 puzzles. v1.1 adds another 8 puzzles and two new opcodes.
Programming
The BOX-256 virtual CPU supports 13 instructions:
| Instruction | Description |
|---|---|
| MOV A B C | copy C cells from A to B |
| PIX A B | display a pixel of colour B in location A |
| FLP A B C | exchange C cells at A and B |
| ADD A B C | Set C = A + B |
| SUB A B C | Set C = A - B |
| MUL A B C | Set C = A * B |
| DIV A B C | Set C = A / B |
| MOD A B C | Set C = A % B (added in v1.1) |
| JMP A | jump to the instruction at A |
| JEQ A B C | jump to the instruction at C if A = B |
| JNE A B C | jump to the instruction at C if A != B (added in v1.1) |
| JGR A B C | jump to the instruction at C if A > B |
| THR A | start a new thread at A |
There are three different addressing modes:
| Mode | Description |
|---|---|
| 0 | constant |
| @ | address |
| * | pointer |
The instruction pointer is stored in address @FF. The instruction pointer for any additional threads is stored at @FE, @FD, etc.
Example
The following example displays a checkerboard pattern:
FLP @16 @17 001 PIX 000 @17 000 ADD 010 @05 @05 JGR @05 00F @00 ADD 001 @05 @05 JMP @04 002 003
