Programming
The SSEM's three bit instruction set allowed a maximum of eight (23) different instructions. In contrast to the modern convention, the machine's storage was arranged with the least significant digits to the left; thus a one was represented in three bits as "100", rather than the more conventional "001".
| Binary code | Original notation | Modern mnemonic | Operation |
|---|---|---|---|
| 000 | S, Cl | JMP S | Jump to the instruction at the address obtained from the specified memory address S (absolute unconditional jump) |
| 100 | Add S, Cl | JRP S | Jump to the instruction at the program counter plus (+) the relative value obtained from the specified memory address S (relative unconditional jump) |
| 010 | -S, C | LDN S | Take the number from the specified memory address S, negate it, and load it into the accumulator |
| 110 | c, S | STO S | Store the number in the accumulator to the specified memory address S |
| 001 or 101 |
SUB S | SUB S | Subtract the number at the specified memory address S from the value in accumulator, and store the result in the accumulator |
| 011 | Test | CMP | Skip next instruction if the accumulator contains a negative value |
| 111 | Stop | STP | Stop |
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