Showing posts with label Definitions. Show all posts
Showing posts with label Definitions. Show all posts
XMS (Extended Memory Specification)
RAM (random access memory) above the 1-MB address. Extended memory is accessed through an extended memory manager (HIMEM.SYS for DOS).
Word
The largest amount of data that can be handled by the microprocessor in one operation and also, as a rule, the width of the main data bus.
Windows File Protection
A background service in Windows 9x, Windows NT, and Microsoft Windows 2000 that tracks any modification to core system files and warns of potential problems.
Wildcards
A keyboard character that represents one or more characters in a string, usually for specifying more than one file by name. The question mark (?) matches any character in a specified position, and the asterisk (*) matches any number of characters up to the end of the filename or extension.
Warm Boot
The process of restarting a computer that is already running by holding down the Ctrl, Alt, and Delete keys simultaneously. It can also refer to choosing a Shut Down And Restart option in Microsoft Windows 9x or Windows NT.
WAN (Wide Area Network)
A network that spans a large geographical area. The network is connected by means of telephone lines, ISDN (Integrated Services Digital Network) lines, DSL, cable, radio waves, or satellite links.
Define Volts
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.
Virtual Memory
Hard disk space that can be used as additional memory for holding data not immediately required by the processor.
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 multi-tasking. Windows is not compatible with the VCPI specification.
VGA (Video Graphics Array)
A graphics adapter that offers 16 colors at a resolution of 640 pixels × 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.
USB (Universal Serial Bus)
A new external expansion bus that is popular for use with low-speed mass storage devices such as Zip drives, modems, and printers.
UPS (Uninterruptible Power Supply)
Acts as both a surge suppressor 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.
UMB (upper memory block)
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.
UMA (Upper Memory Area)
The area from 640 KB to 1024 KB that is designated for hardware needs such as video RAM, BIOS, and memory-mapped hardware.
Twisted-pair Cable
Consists of two insulated wires twisted around each other to form a pair. One or more twisted pairs are used in a twisted-pair cable.
TSR (terminate-and-stay-resident program)
A computer program, also known as a memory-resident program, that remains in memory after being run so that it can be called up later. These extend the capabilities of the operating system or provide "pop-up" functions (such as a calendar or calculator) that can be brought up in the middle of another program without disturbing that program. These programs were popular in the days of MS-DOS, but lead to numerous problems due to memory usage conflicts.
Transistor
An electronic device that allows a small current in one place to control a larger current in another place; commonly used as amplifiers in radio and audio circuits.
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