Specifications

Glossary
3
80386DX An Intel microprocessor with 32-bit
registers, a 32-bit data bus, and a 32-bit address bus.
This processor can operate in real, protected virtual,
and virtual real modes.
80386SX An Intel microprocessor with 32-bit
registers, a 16-bit data bus, and a 24-bit address bus.
This processor, designed as a low-cost version of the
386DX, can operate in real, protected virtual, and
virtual real modes.
80387DX An Intel math coprocessor designed to
perform floating-point math with much greater
speed and precision than the main CPU. The
80387DX can be installed in most 386DX-based
systems and adds more than 50 new instructions to
those available in the primary CPU alone.
80387SX An Intel math coprocessor designed to
perform floating-point math with much greater
speed and precision than the main CPU. The
80387SX can be installed in most 386SX-based
systems and adds more than 50 new instructions
to those available in the primary CPU alone.
80486 See 80486DX.
80486DX An Intel microprocessor with 32-bit
registers, a 32-bit data bus, and a 32-bit address bus.
The 486DX has a built-in cache controller with
8KB of cache memory as well as a built-in math
coprocessor equivalent to a 387DX. The 486DX can
operate in real, protected virtual, and virtual real
modes.
80486DX2 A version of the 486DX with an
internal clock-doubling circuit that causes the chip
to run at twice the motherboard clock speed. If the
motherboard clock is 33MHz, the DX2 chip will
run at 66MHz. The DX2 designation applies to
chips sold through the OEM market, whereas a
retail version of the DX2 sold by Intel and designed
for use as an upgrade was sold as an Overdrive
processor.
80486DX4 A version of the 486DX with an
internal clock-tripling circuit that causes the chip
to run at three times the motherboard clock speed.
If the motherboard clock is 33.33MHz, the DX4
chip will run at 100MHz.
80486SX An Intel microprocessor with 32-bit
registers, a 32-bit data bus, and a 32-bit address bus.
The 486SX is the same as the 486DX, except that it
lacks the built-in math coprocessor function and
was designed as a low-cost version of the 486DX.
The 486SX can operate in real, protected virtual,
and virtual real modes.
80487SX An Intel microprocessor with 32-bit
registers, a 32-bit data bus, and a 32-bit address bus.
Although the name implies that the 80487SX adds
floating-point math capabilities, in reality the
487SX is the same as the 486DX, except that it uses
a modified pinout and must be installed in a spe-
cial 80487SX socket. When installed, the 80487SX
replaces the 80486SX for all processing tasks. The
487SX can operate in real, protected virtual, and
virtual real modes.
A+ Refers to the CompTIA A+ Certification, a
vendor-neutral certification for computer hardware
technicians. A+ Certification exams test knowledge
of basic hardware and software skills. The A+
Certification can be used as part of the exam
requirements for the Microsoft Certified System
Administrator (MCSA) credential.
abend Short for abnormal end. A condition that
occurs when the execution of a program or task is
terminated unexpectedly because of a bug or crash.
absolute address An explicit identification of a
memory location, device, or location within a
device.
AC (alternating current) The frequency is
measured in cycles per seconds (cps) or hertz (Hz).
The standard value running through the wall outlet
is 120 volts at 60Hz through a fuse or circuit breaker
that usually can handle about 15 or 20 amps.
accelerated graphics port See AGP.
Accelerated Hub Architecture (AHA) An
Intel technology used on its 800-series chipsets to
transfer data between the memory controller hub
(MCH), which is equivalent to the North Bridge,
and the input/output controller hub (ICH), which
is equivalent to the South Bridge. AHA transfers
data at 266MBps, twice the speed of the PCI bus
previously used.
accelerator board An add-in board replacing
the computer’s CPU with circuitry that enables
the system to run more quickly. See also graphics
accelerator.
Appendix A
24_0789736977_AppA.qxd 8/15/07 9:24 AM Page 3