Example program that counts up and down between 0 and 255 in an infinite loop.
| # | Instruction | Address | Memory | Comment |
|---|---|---|---|---|
| 0 | OUT | 0000 | 1110 0000 | Output the value of the A-register |
| 1 | ADD 15 | 0001 | 0010 1111 | Put the value of the X variable in the B-register and store A+B in the A-register |
| 2 | JC 4 | 0010 | 0111 0100 | Jump to instruction 4 if the A-register is past 255 |
| 3 | JMP 0 | 0011 | 0110 0000 | Jump to instruction 0 |
| 4 | SUB 15 | 0100 | 0011 1111 | Put the value of the X variable in the B-register and store A-B in the A-register |
| 5 | OUT | 0101 | 1110 0000 | Output the value of the A-register |
| 6 | JZ 0 | 0110 | 1000 0000 | Jump to instruction 0 if the A-register is 0 |
| 7 | JMP 4 | 0111 | 0110 0100 | Jump to instruction 4 |
| 15 | X | 1111 | 0000 0001 | The X variable predefined with the value 1 |
This table displays the values of registers, variables and output after the first 5 iterations of the program, and at the 2 points where it switches between increasing and decreasing.
| 0 | 1 | 2 | 3 | 4 | ... | 253 | 254 | 255 | 256 | 257 | ... | 508 | 509 | 510 | 511 | 512 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | 1 | 2 | 3 | 4 | 5 | 254 | 255 | 0+C,255 | 254 | 253 | 2 | 1 | 0+Z,1 | 2 | 3 | ||
| B | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| X | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | ||
| OUT | 0 | 1 | 2 | 3 | 4 | 253 | 254 | 255,255 | 254 | 253 | 2 | 1 | 0,0 | 1 | 2 |
- Iteration 255 does both an ADD and a SUB due to the carry flag being set during ADD.
- Iteration 510 does both an SUB and a ADD due to the zero flag being set during SUB.
- Both results in the same value being output twice.
This program is from Conditional jump instructions.