APA-1460 SlimSCSI Technical Reference
Glossary-2
APA-1460 SlimSCSI Technical Reference
Stock Number: 510671-00 Rev. A
Page: -2
Print Spec Number: 492966-00
Current Date: 8/22/94
ECN Date: 8/30/94
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files and software programs. Like the audio
CDs used in consumer CD players, the data
on CD-ROM discs cannot be changed once
it is encoded. A single CD-ROM can hold
600 MBytes or more of data.
CD-ROM Drive
A disk device used to retrieve data and
software programs from CD-ROMs (com-
pact disks) for use on computer systems.
Some CD-ROM drives are installed inter-
nally in the computer case, others are used
as external devices. Most CD-ROM drives
can also play audio CDs.
Common Command Set
A de facto standard SCSI command set for
communication with hard disk drives. The
Common Command Set (CCS) is the basis
for the SCSI-2 command set for all types of
peripheral devices.
Conventional Memory
The first 640 KBytes of computer memory.
DOS uses this memory area to run software
applications.
D
Device Driver
A software program that enables a com-
puter to communicate with peripheral
devices, such as hard disk drives and
CD-ROM drives. Each type of device needs
a different driver. Device drivers are stored
on a computer’s hard disk and are typically
loaded into memory at boot time.
Disconnect/Reconnect
Disconnect occurs when a target releases
control of the SCSI bus, allowing the bus to
go to the Bus Free phase. Reconnect occurs
when a target selects an initiator to con-
tinue an operation after a disconnect. This
features allows the device to use the SCSI
bus while other devices prepare to transfer
data or complete commands.
DOS
Disk Operating System. An operating sys-
tem developed by Microsoft
®
Corporation
for use with their x86 family of processors.
DOS is used on most personal computers.
Driver
See Device Driver.
E
EEPROM
Electrically-Erasable Programmable Read
Only Memory. An integrated circuit typi-
cally used to store configuration informa-
tion. Some host adapters have an EEPROM
that contains configuration information.
The data stored in an EEPROM can be
updated while it is installed in the host
adapter.
External SCSI Device
A SCSI device such as a hard disk drive or
tape drive installed outside the computer
case. External SCSI devices are connected
to the SCSI bus with round cables that have
layered twisted pair assemblies with elec-
trical shielding.
EZ
-
SCSI
See Adaptec EZ-SCSI.
F
Fast SCSI
A SCSI standard that allows data to be
transferred at up to 10 MBytes/sec on an
8-bit SCSI bus and up to 20 MBytes/sec on
a 16-bit (Wide) SCSI bus. The Fast SCSI bus
is limited to 3 meters of cable.
FIFO
First In/First Out. An integrated circuit
that buffers data in such a manner that each
byte placed in the buffer is removed from
the buffer in the same order.
G
GByte
Gigabyte. A measure of computer storage.
One GByte equals 1,073,741,824 bytes. (A
byte is the amount of storage needed to
hold one character.)
H
Host
A microcomputer system in which a SCSI
host adapter is installed. The host uses soft-
