SCSI Glossary

Access Time:The time it takes for a disk drives head to reach a sector after the
issuance of a read or write command. Command overhead + seek
time + latency = access time.
Address: (SCSI)The ID number of a target or host on the SCSI Bus. Must be
between 0 – 7, and no two devices can have the same ID number.
Average Seek Time:The milliseconds of time that it takes to do all possible seeks on a
drive divided by the number of seeks possible.
Bit:The binary digit representation of 0 and 1. This is the basic
language of computers, states of either ons or offs.
Block:Usually 512 bytes of information and a common unit that is
transferred at one time to and from a hard drive or to and from
ram memory.
Byte:A group of eight bits. This is the standard size unit for computer
CD-ROM:A storage device that is commonly used on computer Systems.
Holds up to 650 Megabytes of information. You can not write to
a CD-ROM, only read from it.
CPU:Central Processing Unit: The heart of the computer. Usually one
large integrated circuit.
Data-Transfer Rate:How fast a drive or other device can transfer bytes of information.
Device Driver:A piece of software that controls the operation of any attached
SCSI device.
Firmware:Software instructions that are stored in ROM directly on the drive
or SCSI device. Fragmentation: With use over time, the sectors
of a file are written in different areas across the platters surface.
This slows access time.
Gigabyte:1024 Megabytes
KB/s:Kilobytes per second, or 1,000 bytes per second.
Kb/s:Kilobits per second, or 1,000 bits per second.
MB/s:Megabytes per second, or 1,000,000 bytes per second.
Mb/s:Megabits per second, or 1,000,000 bits per second
Partition:A defined part of a drive that is allocated to a specific user or
Peripheral:A device (target) that is attached to the SCSI bus. It can also be
any device attached to a computer system.
Platter:The disk that rotates inside of a drive and where the data is stored.
SCSI:Small Computer System Interface. A bus structure in which
peripherals can be easily and quickly attached to a host computer.
Sector:An allocated amount of space on a platter. Usually 512 bytes
per sector.
Tracks:Invisible magnetic “grooves,” in the form of concentric circles that
store data on a platter.