• U/L Universal/Local
• UA Unnumbered Acknowledgment / User Agent
• UAE Unrecoverable Application Error
• UART Universal Asynchronous Receiver/Transmitter
• UDP User Datagram Protocol
• UI Uncheck Item
• ULP Upper Layer Protocols
• UMB Upper Memory Blocks
• UNMA Unified Network Management Architecture
• UPS Uninterruptable Power Supply
• URL Uniform Resource Locator
• USL Unix Systems Lab
• UTC Universal Time Coordinated
• UTP Unshielded Twisted Pair
• UUCP UNIX to UNIX Copy Program
• UV-EPROM Ultra Violet Erasable Programmable Read Only Memory
• UVGA Ultra-Video Graphics Array