Motherboard
- the principle printed
circuit board assembly in a computer;
includes
core logic (chipset),
interface sockets and/or slots, and
input/output (I/O)
ports .
Printed circuit board (PCB) - a
thin ,
laminated sheet composed of a series of epoxy
resin and
copper layers
and etched electronic circuits (signal,
ground and
power )
Chipset
(or core logic) - two or more
integrated circuits which
control the
interfaces
between the system processor, RAM, I/O devises, and
adapter cards.
Processor slot / socket
- the slot or socket used to
mount the system processor on the
motherboard
AGP
- Accelerated Graphics Port - a high
speed interface for video cards;
runs at 1X (66MHz), 2X (133MHz), or 4X (266MHz).
PCI
- Peripheral
Component Interconnect - a high speed interface for
video cards,
sound cards,
network interface cards, and modems; runs
at 33MHz.
ISA
-
Industry Standard
Architecture - a relatively low speed interface
primarily used for sound cards and modems; runs at approx. 8MHz.
RAM
-
Random Access Memory - see System RAM
Port
(
serial ,
parallel , PS/2, USB, sound, LAN, VGA,
SCSI ) - interface
connectors for the associated
types of
devices Serial
- a low speed interface
typically used for
mice and
external modems
Parallel
- a low speed interface typically used for printers
PS/2
- a low speed interface used for mice and keyboards
USB
-
Universal Serial Bus - a
medium speed interface typically used for
mice, keyboards, scanners, display panels (
control features , not
data), speakers (control features, not sound), scanners, and some
digital cameras.
VGA
- Video Graphics Adapter - the interface from your video card or
integrated video
connector and the system display
monitor .
SCSI
(interface) - Small Computer System Interface - the interface between
a SCSI controller and an external or
internal SCSI
device .
Jumper
- a small block (approx .250"
wide x .312" long x .125"
thick with two
holes running lengthwise which are connected with a
metal structure), or the functionally equivalent electronic
"interconnect"; used to
enable , disable, or
select operating parameter on a motherboard or
other PCB by either
electrically
connecting two
pins on the PCB (closed) or separating
them (
open - only one pin is covered or the jumper is removed).
Connector
header
- a series of two or more metal pins on the motherboard or other PCB;
used to attach a
cable to indicator
lights , switches, and/or other
devices in the computer
Jumper
header
- two pins or a series of two-pin groups where jumpers are used.
BIOS
- Pronounced "bye-ose," an acronym for
basic input/output
system. The BIOS is
built -in software that determines what a computer
can do
without accessing programs from a
disk . On PCs, the BIOS
contains all the
code required to control the
keyboard , display
screen , disk
drives , serial communications, and a number of
miscellaneous
functions .
The BIOS is typically placed in a ROM
chip that
comes with the computer (it is often called a ROM BIOS).
This ensures that the BIOS will always be
available and will not be
damaged by disk failures. It also
makes it possible for a computer to
boot itself. Because RAM is faster
than ROM, though, many computer
manufacturers design systems so that the BIOS is copied from ROM to
RAM each time the computer is booted. This is
known as
shadowing .
Many modern PCs have a
flash BIOS, which
means that the BIOS has
been recorded on a flash
memory chip, which can be updated if
necessary .
The PC BIOS is fairly standardized, so all PCs are
similar at this level (
although there are
different BIOS versions).
Additional DOS functions are
usually added
through software modules.
This means you can upgrade to a newer
version of DOS without
changing the BIOS.
PC BIOSes that can
handle Plug-and-Play (PnP) devices
are known as PnP BIOSes, or PnP-
aware BIOSes.
These BIOSes are always
implemented with flash memory
rather than ROM.
Driver
- software which defines the
characteristics of a device for use by
another device or other software
Cable
set
- one or more interface cables (typically, in relation to a
motherboard, includes cables for a
floppy drive ,
hard drive, and
CD-ROM drive; may
include cables between an internal connector header
and a
bracket or other opening at the
front of
rear of the system;
may include cables for
both IDE/
ATAPI and SCSI devices).
Processor
- the "central processing
unit " (CPU); the principle
integrated circuit used for doing the "computing" in
"personal computing"
System
RAM
- the random access memory (RAM) used by the CPU for computational
purposes
Chassis
- the structure used to house the various "internal"
components of the computer (i.e., the motherboard, adapter cards,
various
storage devices, power
supply , etc.) Normally called
case .
Power
Supply
- the device used to
convert , regulate, and transmit external power
for use by the components housed inside the computer chassis.
Socket
7
- The form
factor for fifth-generation CPU
chips from Intel, Cyrix,
and AMD. All
Pentium chips, except Intel's Pentium Pro (Socket 8) and
Pentium II (Slot 1), conform to the Socket 7 specifications. Intel
has decided to phase out Socket 7 and
replace it with Slot 1. But
Intel's competitors,
such as AMD and Cyrix, are sticking with Socket
7, and are
developing an enhanced version.
Socket
8
- The form factor for Intel's Pentium Pro microprocessors. The
Pentium Pro was the
first microprocessor not to use the venerable
Socket 7 form factor. The Pentium II microprocessors use an
even newer form factor called Slot 1.
Socket 8 is a 387-pin ZIF socket
with connections for the CPU and one or two
SRAM dies for the Level 2
(L2)
cache .
Slot
1
- The form factor for Intel's Pentium II processors. The Slot 1
package replaces the Socket 7 and Socket 8 form factors used by
previous Pentium processors. Slot 1 is a 242-contact daughtercard
slot that accepts a microprocessor packaged as a
Single Edge Contact
(SEC)
cartridge . A motherboard can have one or two Slot 1s.
Slot
2
- A chip packaging design used in Intel's newer Pentium II chipsets,
starting with the
Xeon CPU.
While the Slot 1 interface features a
242-contact connector, Slot 2 uses a somewhat wider 330-contact
connector. The
biggest difference between Slot 1 and Slot 2, though,
is that the Slot 2 design allows the CPU to communicate with the L2
cache at the CPU's
full clock speed. In contrast, Slot 1 only
supports
communication between the L2 cache and CPU at
half the CPU's
clock speed.
Xeon
- A line of Pentium II chipsets from Intel introduced in 1998. Unlike
previous Pentium II chips, which used a Slot 1 form factor, Xeon
chips use Slot 2. This allows for faster data transfers between the
CPU and L2 cache. Xeon chip speeds start at 400 MHz.
Cache
- Pronounced
cash , a
special high-speed storage mechanism. It can be
either a reserved
section of main memory or an independent high-speed
storage device. Two types of caching are
commonly used in personal
computers : memory caching and disk caching.
A memory cache,
sometimes called a cache
store or RAM cache, is a portion of memory
made of high-speed static RAM (SRAM) instead of the slower and
cheaper dynamic RAM (
DRAM ) used for main memory. Memory caching is
effective because most programs access the
same data or instructions
over and over. By
keeping as much of this information as possible in
SRAM, the computer avoids accessing the slower DRAM.
Some memory
caches are built into the architecture of microprocessors. The Intel
80486 microprocessor, for example, contains an 8K memory cache, and
the Pentium has a 16K cache. Such internal caches are often called
Level 1 (L1) caches. Most modern PCs also
come with external cache
memory, called Level 2 (L2) caches. These caches sit between the CPU
and the DRAM. Like L1 caches, L2 caches are composed of SRAM but they
are much larger.
Disk caching
works under the same principle as
memory caching, but instead of using high-speed SRAM, a disk cache
uses conventional main memory. The most recently accessed data from
the disk (as well as adjacent sectors) is
stored in a memory
buffer .
When a
program needs to access data from the disk, it first checks
the disk cache to see if the data is there. Disk caching can
dramatically
improve the
performance of applications, because
accessing a byte of data in RAM can be thousands of
times faster than
accessing a byte on a hard disk.
When data is
found in the cache,
it is called a cache hit, and the effectiveness of a cache is judged
by its hit
rate . Many cache systems use a technique known as
smart caching, in which the system can recognize certain types of
frequently used data. The
strategies for determining which
information should be
kept in the cache constitute some of the more
interesting problems in computer
science .
L1
Cache
- Short for Level 1 cache, a memory cache built into the
microprocessor. See under cache. The L1 cache is also called the
primary cache.
L2
Cache
- Short for Level 2 cache, cache memory that is external to the
microprocessor. In general, L2 cache memory, also called the
secondary cache, resides on a separate chip from the microprocessor
chip. The Pentium Pro,
however , has an L2 cache on the same chip as
the microprocessor.
ACPI
- Short for
Advanced Configuration and Power Interface, a power
management specification
developed by Intel,
Microsoft , and
Toshiba .
ACPI, which will be
part of the next version of
Windows , enables the
operating system to control the
amount of power
given to each device
attached to the computer. With ACPI, the operating system can
turn off peripheral devices, such as a CD-ROM players, when they're not in
use. As another example, ACPI will enable manufacturers to produce
computers that automatically power up as soon as you
touch the
keyboard.
APM
- Short for Advanced Power Management, an API developed by Intel and
Microsoft that allows developers to include power management in
BIOSes. APM defines a layer between the hardware and the operating
system that effectively
shields the programmer from hardware
details .
APM is
expected to be gradually replaced by ACPI.
SOHO
- Acronym for Small Office/Home Office, the fastest growing
market for computer hardware and software. So-called SOHO
products are
specifically
designed to meet the needs of professionals who
work at
home or in small offices.
ECP
- Short for
Extended Capabilities Port, a parallel-port standard for
PCs that supports bi-directional communication between the PC and
attached devices (such as a printer). ECP is about 10 times faster
than the older Centronics standard.
Another modern parallel port
for PCs that
offers similar performance is the EPP (Enhanced Parallel
Port).
EPP
- Short for Enhanced Parallel Port, a parallel port standard for PCs
that supports bi-directional communication between the PC and
attached devices (such as a printer). EPP is about 10 times faster
than the older Centronics standard.
Another modern parallel port
for PCs that offers similar performance is the ECP (Extended
Capabilities Port).
ECC
- Short for
Error -Correcting Code memory, a type of memory that
includes special circuitry for
testing the
accuracy of data as it
passes in and out of memory.
DMI
- Short for
Desktop Management Interface, an API to enable software
to
collect information about a computer environment. For example,
using DMI a program can determine what software and expansion boards
are installed on a computer.
DMI is designed to be
platform -independent and operating system -independent so that programs can
make the same
function calls to collect information no
matter what
system they're running in. This system independence is implemented by
collecting information from MIF files, which are
plain text files
containing information about a software or hardware component.
DMI
was designed by the Desktop Management
Task Force (DMTF), a
consortium of hardware manufacturers led by Intel. Version 2.0 allows
a central computer not only to gather information about computers
connected to a network, but also to configure them. PCs that comply
with DMI 2.0 are sometimes called
managed PCs.
SDRAM
- Short for Synchronous DRAM, a new type of DRAM that can run at much
higher clock speeds than conventional memory. SDRAM actually
synchronizes itself with the CPU's bus and is capable of running at
100 MHz, about three times faster than conventional FPM RAM, and
about twice as
fast EDO DRAM and BEDO DRAM. SDRAM is replacing EDO
DRAM in many newer computers
Today 's fastest Pentium systems use
CPU
buses running at 100 MHz, so SDRAM can
keep up with them, though
barely. Future PCs, however, are expected to have CPU buses running
at 200 MHz or faster. SDRAM is not expected to
support these high
speeds which is why new memory technologies, such as RDRAM and
SLDRAM, are being developed.
EDO
- Short for Extended Data Output Dynamic Random Access Memory, a type
of DRAM that is faster than conventional DRAM. Unlike conventional
DRAM which can only access one block of data at a time, EDO RAM can
start fetching the next block of memory at the same time that it
sends the previous block to the CPU.
DIMM
- Short for
dual in-line memory
module , a small circuit board that
holds memory chips. A single in-line memory module (
SIMM ) has a
32-bit
path to the memory chips whereas a DIMM has 64-bit path.
Because the Pentium processor
requires a 64-bit path to memory, you
need to
install SIMMs two at a time. With DIMMs, you can install
memory one DIMM at a time.
SIMM
- Acronym for single in-line memory module, a small circuit board
that can
hold a group of memory chips. Typically, SIMMs hold up 8 (on
Macintoshes) or 9 (on PCs) RAM chips. On PCs, the ninth chip is often
used for
parity error checking. Unlike memory chips, SIMMs are
measured in bytes rather than
bits . SIMMs are
easier to install than
individual memory chips.
The bus from a SIMM to the actual memory
chips is 32 bits wide. A newer
technology , called dual in-line memory
module (DIMM), provides a 64-bit bus. For modern Pentium
microprocessors that have a 64-bit bus, you must use either DIMMs or
pairs of SIMMs.
Chipset
Models
- Today there are many chipset models in the marketplace. The most
popular for mainstream desktop computers are Intel's 810, BX, LX, and
ZX. There are also "third
party " chipsets available from
Acer Labs (ALi),
Silicon Integrated Systems (SiS), and VIA
Technologies (VIA). The
latter are
quite similar to their Intel
counterparts but may add features not available in the Intel
chipsets. The third party chipsets may also support non-Intel
processors (like those from AMD and
others that have a 100MHz data
bus and use the "Socket 7" processor-to-motherboard
socket). Intel also produces chipsets that support dual processors.
[At the time this FAQ was prepared, only Intel was producing chipsets
which support multiple processors.] The
following are
brief descriptions of the key features of the most popular primary Intel
and third party chipsets as of the
date this FAQ was prepared
(mid-
June '99).
Intel
810
- "Basic PC and Mainstream segments", supports 2 DIMM (max.
512MB), SDRAM only, ECC/parity not supported, integrated "
direct "
AGP, integrated graphics controller (enhanced i740), 66/100MHz data
bus,
Ultra ATA/66 device support.
Intel
440BX
- "Performance
segment ", supports 4 DIMM (max 1GB),
SDRAM only, ECC/parity supported, AGP 2X, 66/100MHz data bus, Ultra
ATA/33 device support; dual processor support.
Intel
440GX
- "Workstation segment", supports 4 DIMM (max 2GB), SDRAM
only, ECC/parity supported, AGP 2X, 100MHz data bus, Ultra ATA/33
device support; dual processor support; supports Pentium II/III and
Pentium Xeon II/III (slot 2).
Intel
440LX
- "Basic PC segment", supports 4 DIMM (max 512MB SDRAM, 1GB
EDO), ECC/parity supported, AGP 2X, 66MHz data bus, Ultra ATA/33
device support; dual processor support
Intel
440ZX
- "Mainstream segment", supports 2 DIMM (max 256MB), SDRAM
only, ECC/parity not supported, AGP 2X, 66/100MHz data bus, Ultra
ATA/33 device support.
ALi 1541
- mainstream (Socket 7), supports 3 DIMM, 100MHz data bus, AGP 2X
SiS
530
- mainstream (Socket 7), supports 3 DIMM, 100MHz data bus, AGP 2X,
integrated graphics controller
SiS
600
- mainstream (Pentium II/III), supports 3 DIMM, 100MHz data bus, AGP
2X
VIA Apollo Pro
- mainstream (Pentium II/III), supports 4 DIMM, 100MHz data bus, AGP
2X
Form
Factor
- the
physical layout of a motherboard in regards the relative
position of the adapter card expansion slots, the number of those
slots, the relative
size of the motherboard, and the orientation of
the board in the chassis . For the
purpose of this FAQ, only the Baby
AT (BAT), ATX, and MicroATX form factors will be
considered .
Baby
AT (BAT)
- this is the oldest of the currently available, mainstream
motherboard form factors. Its distinguishing features are its
orientation in the chassis (the long
axis goes from the
back to the
front of the chassis), the type of keyboard connector (typically
referred to as a "large DIN" connector), the presence of AT
or PS/2 power supply connectors (a series of 12 "blades" in
one or two adjacent
male connectors), and the implementation of the
various I/O connectors (serial and parallel ports) via a bracket
which goes into one of the adapter card slots at the rear of the
chassis.
Please note that in some motherboards there may also be an
ATX power supply connector (a rectangular grouping of 20 small
sockets in two adjacent rows of 10).
ATX
- this is the most common of today's mainstream motherboard form
factors. Its distinguishing features are its orientation in the
chassis (the long axis goes from side-to-side at the rear of the
chassis), the use of "integrated I/O connectors" (all the
connectors are built into the motherboard and
exit to the rear of the
chassis through an "I/O
shield " where they are grouped
together), and only an ATX power supply connector is
provided .
MicroATX
- this is a
variation of the ATX form factor. It is much shorter in
its long axis than the ATX and has fewer adapter card slots (3
compared to the ATX with typically 7). Otherwise the features are the
same as the ATX.
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