| Abbreviation | Definition |
|---|---|
| ULSI | Ultra Large Scale Integration |
| ULT | User Level Thread |
| UMA | Uniform Memory Access |
| UMG | Ultimate Memory Guide |
| UML | Unified Modeling Language |
| UML | User Mode Linux |
| UMP | Universal Module Player |
| UMPC | Ultra-Mobile Personal Computer |
| UMR | Universal Media Reader |
| UMS | U S B Mass Storage |
| UMTS | United Mobile Talking Switch |
| UNC | Uniform Naming Convention |
| UNIVAC1 | Universal Automatic Computer 1 |
| UNIX | Uniplexed Information and Computing Service |
| UNW | UNWind |
| UNZ | Unzip |
| UO | Unlimited Output |
| UOL | users on-line |
| UOS | Micro Operating System |
| UP | User Profile |