| 3499 | O.K. Yah! | ZX-Spectrum 48K | English |
| 14477 | O.S. Quiz | ZX-Spectrum 48K | English |
| 19295 | O/A-Level Physics Definitions | ZX-Spectrum 48K | English |
| 41145 | O/S Disassembler | ZX81 16K | English |
| 32302 | OKNOTOK | ZX-Spectrum 48K | English |
| 2001160 | OMNI Complete Catalog of Computer Hardware and Accessories | - | English |
| 45425 | ON and OFF | ZX-Spectrum 48K | English |
| 17912 | ONELINERS | ZX-Spectrum 48K | English |
| 34298 | OPZ | ZX-Spectrum 48K | English |
| 39230 | ORG | ZX-Spectrum 48K | English |
| 27143 | ORGANize | ZX-Spectrum 48K | English |
| 4000209 | OS DRAW | Timex Tx2068 | English |
| 40829 | OSCAR-9 Azimuth/Elevation Table | ZX-Spectrum 48K | English |
| 35842 | OTHELLO2 | ZX81 16K | English |
| 17606 | OTWOC | ZX-Spectrum 48K | English |
| 39622 | OUT 254 | ZX-Spectrum 48K | English |
| 27890 | OUTplay | ZX-Spectrum 128K | English |
| 18413 | OXO | ZX-Spectrum 16K | English |
| 26065 | OXO | ZX-Spectrum 16K | English |
| 25868 | OXO | ZX-Spectrum 48K | English |