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- Select the first letter of the word from the
list above to jump to appropriate section of the glossary.
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- Alias
- An alias is an alternate name used to refer to something or
someone
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- BIOS
- Acronym for basic input/output system. On
PC-compatible computers, the set of essential software routines that test hardware at
startup, start the operating system, and support the transfer of data among hardware
devices. The BIOS is stored in read-only memory (ROM) so that it can be executed when the
computer is turned on. Although critical to performance, the BIOS is usually invisible to
computer users.
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- DRAM
- A form of semiconductor random access memory (RAM). Dynamic RAMs
store information in integrated circuits containing capacitors. Because capacitors lose
their charge over time, dynamic RAM boards must include logic to refresh (recharge) the
RAM chips continuously. While a dynamic RAM is being refreshed, it cannot be read by the
processor; if the processor must read the RAM while it is being refreshed, one or more
wait states occur. Despite being slower, dynamic RAMs are more commonly used than RAMs
because their circuitry is simpler and because they can hold up to four times as much
data.
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- Disk Controller
- A special-purpose chip and associated circuitry that directs and
controls reading from and writing to a computer's disk drive. A disk controller handles
such tasks as positioning the read/write head, mediating between the drive and the
microprocessor, and controlling the transfer of information to and from memory. Disk
controllers are used with floppy disk drives and hard disks and can either be built into
the system or part of a card
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- E
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- EISA
- Acronym for Extended Industry Standard Architecture. A bus
standard for the connection of add-on cards to a PC motherboard, such as video cards,
internal modems, sound cards, drive controllers, and cards that support other peripherals.
EISA was introduced in 1988 by a consortium of nine computer-industry companies. The
companies— AST Research, Compaq, Epson, Hewlett-Packard, NEC, Olivetti, Tandy, Wyse,
and Zenith. EISA has a 32-bit data path, and it uses connectors that can accept ISA cards.
However, extended ISA cards are compatible only with Extended ISA systems. Extended ISA
can operate at much higher frequencies than the ISA bus and provides much faster data
throughput than ISA.
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- Flash Memory
- A type of nonvolatile memory. Flash memory is similar to EEPROM
memory in function but it must be erased in blocks, whereas EEPROM can be erased one byte
at a time. Because of its block-oriented nature, flash memory is commonly used as a
supplement to or replacement for hard disks in portable computers. In this context, flash
memory either is built into the unit or, more commonly, is available as a PC Card that can
be plugged into a PCMCIA slot. A disadvantage of the block-oriented nature of flash memory
is that it cannot be practically used as main memory (RAM) because a computer needs to be
able to write to memory in single-byte increments.
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- Floppy Disk
- A round piece of flexible plastic film coated with ferric oxide
particles that can hold a magnetic field. When placed inside a disk drive, the floppy disk
rotates to bring different areas, or sectors, of the disk surface under the drive's
read/write head, which can detect and alter the orientation of the particles' magnetic
fields to represent binary 1s and 0s. A floppy disk 5.25 inches in diameter is encased in
a flexible plastic jacket and has a large hole in the center, which fits around a spindle
in the disk drive; such a disk can hold from a few hundred thousand to over one million
bytes of data. A 3.5-inch disk encased in rigid plastic is also called a floppy disk or a
microfloppy disk. In addition, 8-inch floppy disks were common in DEC and other
minicomputer systems.
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- Hard Disk
- A device containing one or more inflexible platters coated with
material in which data can be recorded magnetically, together with their read/write heads,
the head-positioning mechanism, and the spindle motor in a sealed case that protects
against outside contaminants. The protected environment allows the heads to fly 10 to 25
millionths of an inch above the surfaces of platters rotating typically at 3600 rpm;
therefore, much more data can be stored and accessed much more quickly than on a floppy
disk. Most hard disks contain from two to eight platters. Also called hard disk drive.
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- I
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- ISA
- Acronym for Industry Standard Architecture. A bus design
specification that allows components to be added as cards plugged into standard expansion
slots in IBM Personal Computers and compatibles. Originally introduced in the IBM PC/XT
with an 8-bit data path, ISA was expanded in 1984, when IBM introduced the PC/AT, to
permit a 16-bit data path. A 16-bit ISA slot actually consists of two separate 8-bit slots
mounted end-to-end so that a single 16-bit card plugs into both slots. An 8-bit expansion
card can be inserted and used in a 16-bit slot (it occupies only one of the two slots),
but a 16-bit expansion card cannot be used in an 8-bit slot.
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- ISA Slot
- A connection socket for a peripheral designed according to the ISA
(Industry Standard Architecture) standard, which applies to the bus developed for use in
the 80286 (IBM PC/AT) motherboard.
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- J
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- K
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- L
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- LAN
- Acronym for local area network. A group of computers and other
devices dispersed over a relatively limited area and connected by a communications link
that enables any device to interact with any other on the network. LANs commonly include
microcomputers and shared resources such as laser printers and large hard disks. The
devices on a LAN are known as nodes, and the nodes are connected by cables through which
messages are transmitted.
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- M
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- Memory
- Circuitry that allows information to be stored and retrieved. In
the most general sense, memory can refer to external storage such as disk drives or tape
drives; in common usage, it refers only to the fast semiconductor storage (RAM) directly
connected to the processor.
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- Motherboard
- The main circuit board containing the primary components of a
computer system. This board contains the processor, main memory, support circuitry, and
bus controller and connector. Other boards, including expansion memory and input/output
boards, may attach to the motherboard via the bus connector.
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- N
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- Network
- A group of computers and associated devices that are connected by
communications facilities. A network can involve permanent connections, such as cables, or
temporary connection made through telephone or other communication links. A network can be
as small as a local area network consisting of a few computers, printers, and other
devices, or it can consist of many small and large computers distributed over a vast
geographic area.
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- Novell NetWare
- A family of local area network operating system products produced
by Novell, Inc. Designed to run on IBM PCs and Apple Macintoshes, Novell NetWare allows
users to share files and system resources such as hard disks and printers.
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- Network Operating System
- An operating system installed on a server in a local area network
that coordinates the activities of providing services to the computers and other devices
attached to the network. Unlike a single-user operating system, a network operating system
must acknowledge and respond to requests from many workstations, managing such details as
network access and communications, resource allocation and sharing, data protection, and
error control
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- PCI local bus
- Short for Peripheral Component Interconnect local bus. A
specification introduced by Intel Corporation that defines a local bus system for a
computer built to the PCI specification. A PCI local bus system requires the
presence of a PCI controller card, which must be installed in one of the PCI-compliant
slots. The PCI controller can exchange data with the system's CPU either 32 bits or
64 bits at a time, depending on the implementation, and it allows intelligent,
PCI-compliant adapters to perform tasks concurrently with the CPU using a technique called
bus mastering. The PCI specification allows for multiplexing, a technique that permits
more than one electrical signal to be present on the bus at one time.
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- O
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- Q
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- R
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- ROM
- 1. Acronym for read-only memory. A semiconductor circuit into
which code or data is permanently installed by the manufacturing process. The use of this
technology is economically viable only if the chips are produced in large quantities;
experimental designs or small volumes are best handled using PROM or EPROM.
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- 2. Acronym for read-only memory. Any semiconductor circuit serving
as a memory that contains instructions or data that can be read but not modified (whether
placed there by manufacturing or by a programming process, as in PROM and EPROM).
- RAM
- Acronym for random access memory. Semiconductor-based memory that
can be read and written by the CPU or other hardware devices. The storage locations can be
accessed in any order. Note that the various types of ROM memory are capable of random
access, but cannot be written to. The term RAM, however, is generally understood to refer
to volatile memory that can be written to as well as read.
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- S
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- SRAM
- A form of semiconductor memory (RAM) based on the logic circuit
known as a flip-flop, which retains information as long as there is enough power to run
the device. Static RAMs are usually reserved for use in caches.
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- SCSI device
- A peripheral device that uses the SCSI (Small Computer Systems
Interface) standard to exchange data and control signals with a computer's CPU.
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- Token ring network
- A local area network formed in a ring (closed loop) topology that
uses token passing as a means of regulating traffic on the line. On a token ring network,
a token governing the right to transmit is passed from one station to the next in a
physical circle. If a station has information to transmit, it "seizes" the
token, marks it as being in use, and inserts the information. The "busy" token,
plus message, is then passed around the circle, copied when it arrives at its destination,
and eventually returned to the sender. The sender removes the attached message and then
passes the freed token to the next station in line. Token ring networks are defined in the
IEEE 802.5 standards.
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- U
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- V
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- VL bus
- Short for VESA local bus. A type of local bus architecture
introduced by the Video Electronics Standards Association. The VL-bus specification allows
up to three VL-bus slots to be built into a PC motherboard and allows for bus mastering
(wherein "intelligent" adapter cards can do some processing independently of the
CPU). A VL-bus slot consists of a standard connector plus an additional 16-bit Micro
Channel Architecture connector and must be built into the motherboard by the manufacturer.
Standard connectors cannot simply be converted to VL-bus slots. A non-VL-bus adapter card
can be used in a VL-bus slot, but it cannot use the local bus and so performs as it
normally would in a non-VL-bus slot.
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- Video RAM (VRAM)
- A special type of dynamic RAM (DRAM) used in high-speed video
applications. VRAM uses separate pins for the processor and the video circuitry, providing
the video circuitry with a "back door" to the VRAM. The video circuitry can
access the VRAM serially (bit by bit), which is more appropriate for transferring pixels
to the screen than is the parallel access provided by conventional
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- Y
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- Z
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- #
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