TCP - Transmission Control Protocol. Actually a suite of connection-oriented protocols, for transmission of data in byte streams. Data is transmitted in "packets" or small bundles, which contain a TCP header that includes the address to which the data is to proceed.

TELNET - a terminal emulation protocol that allows one to log on to remote computers and issue commands; a program that uses the telnet protocol to communicate.

TIFF - Tagged Image File Format. TIFF provides a way of storing and exchanging digital image data. Aldus Corp., Microsoft Corp. and major scanner vendors developed TIFF to help link scanned images with the popular desktop publishing applications. It is now used for many different types of software applications ranging from fax modem data transfers to CAD programs and 3D graphic packages.

TN3270 - a special version of telnet for communicating with IBM mainframes, which live in a world of their own.

TRACKBALL - Is usually described as an upside-down mouse. A trackball remains stationary on your desk; as you move the sphere (ball) in the center with your fingers or palm, sensors detect movement and cause the on-screen cursor to move. Some of the newer notebook computers have this type of directional device that attaches to one edge of the computer.

TSR - Terminate and Stay Resident programs. These are programs that remain loaded into memory when they finish operating, so that they can be reactivated with just a couple of keystrokes, even when another application is running. TSRs do, however, use memory when loaded, but many of them can be loaded into UPPER MEMORY, freeing CONVENTIONAL MEMORY.

UART, USRT, USART -

Universal Asynchronous Receiver/Transmitter

Universal Synchronous Receiver/Transmitter

Universal Synchronous Asynchronous Receiver/Transmitter

These all are types of integrated circuits (chips) with serial/parallel conversion, parallel/serial conversion, and other facilities designed for use in synchronous and asynchronous serial communications. These devices can take data directly from, or place it directly on the data bus.

UMA and UMBs - Both of these terms describe areas in random access memory above 640K and below 1 MB on microcomputers using Intel 80386 CPUs and later. The UMA, Upper Memory Area, is the expanse of memory between 640K and 1 MB and is normally reserved for hardware use. The ROM BIOS is located in the UMA as well as the ROMs of various adapters in the system such as the video card and the hard disk controller. Expanded memory boards locate their page frames in the UMA. The UMBs, Upper Memory Blocks, are pockets of usable RAM created in unused areas of the UMA. The primary use for UMBs is to store TSRs and device drivers above 640K therefore making more RAM available for application programs.

UNARY OPERATOR - an operator that acts upon a single operand; for example, the negative sign in -6 is a unary operator.

UPPER MEMORY - The area of memory on a DOS based machine located between the 640K DOS CONVENTIONAL MEMORY constraint and the 1024K (1 megabyte) limit of DOS.

USENET - an informal, somewhat archaic (it actually preceded the Internet), system for exchanging "news" postings, which include appeals for help, news of new programs, comments on TV shows, and anything else you can imagine.

UUCP - UNIX to UNIX Copy. A facility for copying files between UNIX computers; e-mail and USENET originally were built on UUCP.

VARIABLE - a parameter that can have several values; the symbol used in a program to represent the parameter.

VGA - Video Graphics Array - The VGA is an analog video controller. It handles color in much the same way as a TV receiver. The VGA produces a signal that can vary in small increments over a large spectrum of colors. The VGA requires an analog color monitor. The VGA provides a text mode with a 9-by-16 dot box for characters, it emulates the EGA modes and the two graphics modes of MCGA, and it provides its own graphics mode with 16 colors and 640-by-480 pixel resolution.

VIRTUAL MEMORY - When a program requires more space than is available in main memory, a direct access (mass) storage device can be used to hold program segments until needed in memory. The swapping of information between actual memory and virtual memory is transparent, so that the program utilizing virtual storage appears to be held entirely in memory. The virtual memory system allows a program to be broken up into segments, called pages. Instead of bringing the entire program into memory, it brings in as many pages that will fit and leaves the remaining pages on disk. When instructions are called for that are not in memory, the appropriate disk page is read in, overlaying a page in memory. The input and output of program pages is called paging or swapping.

VOLATILE MEMORY - Computer memory, made up of dynamic RAM or static RAM chips, is called volatile memory because its contents are lost when the power is shut down. Non-volatile memory, also called firmware, is capable of retaining its contents without power. Examples of non-volatile memory chips: ROM's, PROM's, EPROM's, and EEPROM's.

VRAM - Video Random Access Memory chips are modified DRAM's on video boards to allow them to transfer a large number of bits from the memory array to a separate internal serial-shift register. After making the transfer, the contents of the shift register are independently shifted out to the video display.

VRML - Virtual Reality Modeling Language. A graphics programming language for creating three-dimensional scenes, through which one can seem to move on screen.

WARM BOOT - A computer's operating system is initiated with a boot procedure, a start-up from scratch. It is not always necessary to turn-off the power and then re-apply it to start the boot procedure. If your PC hasn't completely locked up, and the keyboard is active, the system can be warm booted by depressing the following three keys simultaneously: Ctrl-Alt-Del. This procedure is known as the "three finger salute." UNIX machines cannot be similarly restarted.

WILDCARDS - In DOS and UNIX, the two characters, * and ?, can be used when specifying one or more filenames in an operation. These characters are called wildcards. For example, the DOS command DIR *.COM will cause a directory listing of all the files that have the extension .COM to be displayed on the screen. The asterisk (*) character can represent any valid set of up to eight characters. The question mark (?) can represent any single character in a filename. For example, the DOS directory command, DIR SEPT??.DAT would show directory information any files with names starting with SEPT, followed by two characters, with a .DAT extension). The UNIX 'ls' command would work the same way with the same wildcards.

WOM - Write-only Memory. Memory into which information can be written, but from which information cannot be retrieved, or read. WOM devices are used for the disposal of surplus information.

WORM MEMORY - Write Once, Read Many. A CD-ROM is worm memory.

WYSIWYG - What You See Is What You Get. WYSIWYG, pronounced "wizzy-wig", or "wissy-wig", describes computer programs, such as Windows word processors, that generate screen images that are identical in position and type appearance to the final document, as opposed to those that show the formatting or special type requested only when the document is printed, such as the UNIX typesetting program, TeX. The advantages are twofold: the planning of a visually pleasing final document is easier and errors in the printed document can be found more quickly when the document is on the screen.