| A: |
The designation for the first floppy disk
drive in a PC. In earlier PCs that had two floppy drives, the second drive was B:. See
C:.
 |
|
| access time |
(1) Memory access time is how long it
takes for a character in memory to be transferred to or from the CPU. In a personal
computer, fast RAM chips have an access time of 70 nanoseconds (ns) or less. SDRAM chips
have a burst mode that obtains the second and subsequent characters in 10 ns or less.
(2) Disk access time is an average of the time between initiating a request and
obtaining the first data character. It includes the command processing, the average seek
time (moving the read/write head to the required track) and the average latency (rotation
of disk to the required sector). This specification must be given as an average, because
seek times and latency can vary depending on the current position of the head and platter.
Fast hard disks have access times of 10 milliseconds (ms) or less. This is a common speed
measurement, but overall disk performance is significantly influenced by channel speed
(transfer rate), interleaving and caching. See cache,
seek time and latency. |
|
| active matrix |
| An LCD technology used in flat panel computer
displays. It produces a brighter and sharper display with a broader viewing angle than
passive matrix screens. Active matrix technology uses a thin film transistor at each pixel
and is often designated as a "TFT screen." See passive
matrix and LCD. |
|
| ActiveX |
| A brand name from Microsoft that has been used
very specifically and very broadly. Today, it refers generally to ActiveX controls. For a
short time, it was used to brand Microsoft's entire COM object architecture. |
|
| AGP |
(Accelerated Graphics Port)
A high-speed port developed by Intel that is designed for the display adapter (video card)
only. It provides a direct connection between the card and memory, and only one AGP slot
is on the motherboard. AGP was introduced as a higher-speed alternative to the PCI-based
adapter, plus it freed up a PCI slot to be used for another peripheral device. The brown
AGP slot is slightly shorter than the white PCI slot and is located about an inch farther
back.
AGP uses a 32-bit bus. The original AGP standard (AGP 1x) provided a data transfer rate of
264 Mbytes/sec. AGP 2x is 528 Mbytes/sec. AGP 4x is 1 Gbyte/sec. AGP 8x is 2 Gbytes/sec. |
|
| alpha channel |
| An additional eight bits in a 32-bit graphics
pixel that is used as a separate layer for representing levels of translucency in an
object. |
|
| alphanumeric |
| The use of alphabetic letters mixed with
numbers and special characters as in name, address, city and state. The text you're
reading is alphanumeric. |
|
| AT class |
| Refers to second-generation PCs that use the
286 CPU and the 16-bit AT (ISA) bus. In the
mid-1980s, AT class machines were the high-speed PCs of the day. |
|
| AT |
| (Advanced Technology) IBM's
first 286-based PC, introduced in 1984. It was the most advanced machine in the PC line
and featured a new keyboard, a higher-capacity 5.25" floppy (1.2MB) and a 16-bit data
bus. AT-class machines ran considerably faster than the 8088-based XT PCs). See
PC. See also AT keyboard connector. |
|
| ATA |
| (AT Attachment) The specification for
IDE drives. See IDE. |
|
| ATAPI |
| (AT Attachment Packet Interface)
The specification for IDE tape drives and CD-ROMs. See IDE. |
|
| AT
command set |
| A series of machine instructions used to
activate features on an intelligent modem. Developed by Hayes Microcomputer Products and
officially known as the Hayes Standard AT Command Set, it is used entirely or partially by
most every modem manufacturer. AT is a mnemonic code for ATtention, which is the prefix
that initiates each command to the modem. |
|
| Athlon |
A Pentium III-class CPU chip from AMD. The
first models were introduced in 1999 with clock speeds from 500MHz to 650MHz and a 200MHz
system bus. Subsequent models have exceeded 1GHz clock, and the bus was increased to
266MHz. The Athlon contains the MMX multimedia instructions used in Pentium
MMX and Pentium II CPUs along with an enhanced version of AMD's 3DNow
3-D instruction set for faster rendering of games and animation.
The Athlon plugs into a slot, known as Slot A, which is similar to the elongated slot used
by Pentium II's and III's. The Athlon is the successor to the K6 series and was formerly
known as the K7. See Athlon XP, K6 and
Hammer. |
|
| Athlon XP |
| A family of CPU chips from AMD that was
introduced in 2001. Departing from the traditional MHz designation, Athlon XP chips use
model numbers that combine clock speed and architectural features into a numerical rating.
For example, the 1500+, the first XP model, has a clock speed of 1.33GHz, but provides
greater performance than the Athlon 1.4GHz chip. See Athlon. |
|
|
|
| AT keyboard connector |
Refers to the 5-pin DIN connector used on
earlier PC keyboards. It was subsequently replaced with the smaller 6-pin MiniDIN
connector, which is known as a "PS/2 connector" and which was first used on
laptops.
AT and PS/2 Connectors Adapters switch between AT and PS/2 connectors so that your
new keyboard can work with your old PC, or your old keyboard can work with a newer PC or
laptop. |
|
| AT
motherboard |
| A motherboard that uses the same form factor
as the original IBM AT, typically 12x13.5". It was superseded by the 9x10" Baby
AT motherboard. See ATX motherboard. |
|
| ATX motherboard |
A motherboard that superseded the widely-used
Baby AT design. ATX rotates the CPU and memory 90 degrees, allowing full-length boards in
all sockets. The power supply blows air over the CPU rather than pulling air through the
chassis. The Micro ATX is a smaller version of the ATX with fewer slots. See
Baby AT motherboard.
The ATX Motherboard The motherboard glues all the components together via its
various slots. Slot 1 is for the CPU. DIMM
slots hold memory modules, and the AGP, PCI
and ISA slots hold the various adapter cards. Control for the
IDE and floppy disk drives as well as the USB,
mouse, keyboard and serial and parallel ports are built in. (Image courtesy of Soyotek,
Inc.) |
|
| AUI |
| (Attachment Unit Interface)
The network interface used with standard Ethernet. On the adapter card, it is a 15-pin
socket. A transceiver, which taps into the Ethernet cable, plugs into the socket. See
10Base5. |
|
| AUTOEXEC.BAT |
| (AUTOmatic EXECute BATch)
A DOS batch file that is executed when the computer is started. The OS/2 counterpart is
STARTUP.CMD. See DOS AUTOEXEC.BAT. |
|
| Auto Insert Notification |
| The option in Windows that turns the Autoplay
feature on or off. Autoplay runs a program on a CD-ROM or plays a title on an audio CD as
soon as the disc is inserted into the drive and the drive door is closed. Users may elect
to prevent Autoplay by disabling Auto Insert Notification by double clicking the CD-ROM
drive line in Device Manager and selecting the Settings tab. The file on the disc that
Autoplay looks for is AUTORUN.INF. See Device Manager. |
|
| Autoplay |
| A feature that automatically starts playing an
audio CD or runs a program when a disc is inserted into the drive. See Auto Insert Notification. |
|
| AVI |
| (Audio Video Interleaved)
A Windows multimedia video format from Microsoft. It interleaves standard waveform audio
and digital video frames (bitmaps) to provide reduced animation at 15 fps at 160x120x8
resolution. Audio is 11,025Hz, 8-bit samples. |
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