A Glossary for 386


BUS SPEED:  Modems, disk drives and facsimile boards connected to
a bus generally operate at 10 MHz or less.  In contrast, an 80386
CPU's clock speed goes as high as 33 MHz.

CACHE:  Dedicated memory area that buffers data or instructions
ready for use.

CACHING CONTROLLER:  Massive buffer with up to several megabytes
of dedicated RAM to improve hard-disk access time.

DIP:  Dual in-line package, the traditional bug-like integrated
circuit chip.

DRAM:  Dynamic random-access memory chip.

FCC RATING:  Measure of radio-frequency interference from circuitry
signals.  Class A is for office computers.  Class B indicates a
better-shielded machine for use near radios and televisions.

INTERLEAVED MEMORY:  Identical data in two different memory banks. 
One always remains available while the other is being refreshed.

MEMORY CACHE:  Portion of memory set aside and not subtracted from
the 640K that holds the next instructions or data for the CPU;
controlled by dedicated chip or software.

PROTECTED MODE, 286:  16-bit operating mode that assists
multitasking and consumes up to 16M RAM.  An 80286 computer in
protected mode can run only one MS-DOS program under OS/2.

PROTECTED MODE, 386:  A 386 chip can address up to four gigabytes
of memory by switching into 32-bit internal operation.  Few
applications need more than 16M.

REAL 8086 MODE:  Start-up operating mode of 8086/88, 286 and 386
computers.

RFI:  Radio-frequency interference emitted by a poorly shielded
computer or external device such as a hard disk.

SHADOW RAM: Software that loads the 16-bit system or video BIOS
from a chip on the motherboard into faster 32-bit RAM upon 
power-up.

SIMM:  Single in-line memory module carrying many memory chips.

SIP:  Single in-line package.  Integrated circuit chip with all
leads coming off one side.

SRAM:  Static random-access memory chip.  Faster and costlier than
DRAM.

TEMPEST:  The ultimate RFI rating.  A Tempest computer radiates no
electro-magnetic signals that might be intercepted remotely.

VIRTUAL 8086 OPERATION:  An 80386 chip can set aside memory to run
programs on a simple, 8086-like virtual computer.  That is how 386
UNIX operating systems run PC-compatible programs.