universal serial bus (USB)
A new external expansion bus that is popular for use with low-speed mass storage devices such as ZIP drives, modems, and printers.
The ability to transfer (send) a file from one computer to a remote computer.
upper memory area (UMA)
The area from 640 KB to 1024 KB that is designated for hardware needs such as video RAM, BIOS, and memory-mapped hardware.
upper memory blocks (UMB)
The unused spaces in upper memory that can be divided into blocks. These empty blocks have no RAM associated with them and are simply reserved space. This unused space is valuable because, unlike expanded and extended memory, MS-DOS can run programs in UMB.
UPS (uninterruptible power supply)
Acts as both a surge suppresser and a power leveler to provide the computer with a constant source of power. It also provides power during a power failure or interruption so the user can safely save data before shutting down.
The vast collection of discussion groups and newsgroups on the Internet.
VGA (Video Graphics Array)
A graphics adapter that offers 16 colors at a resolution of 640 pixels by 480 pixels. To gain more colors, VGA uses an analog video signal instead of a digital signal. With the analog signal, the VGA standard is able to provide 64 distinct levels for each color, giving users 643 or 262,144 possible colors. It uses a 15-pin, three-row, female DB-type connector.
Virtual Control Program Interface (VCPI)
A memory management specification that accesses extended memory for MS-DOS-based applications. It allows only one application to control extended memory and does not support multitasking. Windows is not compatible with the VCPI specification.
Hard disk space that can be used as additional memory for holding data not immediately required by the processor.
The unit of electromotive force, or the potential energy, that will produce a current of 1 ampere when steadily applied against a resistance of 1 ohm. Voltage is also considered the potential energy of a circuit.
VRR (Vertical Refresh Rate)
The speed at which a monitor completes all vertical traces.