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1.1
Features
Q250 and Q280 drives feature on-board, ANSI-standard, Small Computer
System Interface (SCSI) controllers, and, with the exception of a
plug-in EPROM IC, both models use the same printed circuit board
(PCB).
These drives require no operational adjustments.
All
electronics except the spindle motor, headstack, flex circuit, heads,
and actuator rotor are contained on the PCB. A single IC is mounted on
the flex circuit inside the sealed assembly.
The following features of the Q250/Q280 drives enable high data
throughput:
o
Seeks are initiated immediately--other commands are
processed simultaneously.
o
14 KByte FIFO data buffer balances the transfer of data to
and from the SCSI bus as well as to and from the drive.
o
Optional DisCache increases data buffer size to 60 KBytes.
(See the Q200 Series Programmers Manual for details
concerning this option.)
o
Cylinder and head skewing scheme minimizes latency when
accessing data sequentially across cylinder boundaries.
o
Defect management scheme minimizes seeks to spare sectors.
o
Multiple block transfer of up to 64K-1 blocks, each with up
to 2 Kbytes.
o
RLL 1,7 (run-length-Iimited) encoding increases data density
on the disks.
1-1
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