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Peripheral items
Cache
The drive is fitted with 64kbytes of RAM and read-ahead cache circuitry.
When a read access is made to the drive, subsequent data is read into the RAM. If an
attempt is made to read this data it is accessed from RAM rather than from the disk,
thus considerably reducing access times.
Quantum ProDrive LPS 240AT
The 240 Mbyte hard disk drive that may be fitted in the LS Pro range is a Quantum
ProDrive LPS 240AT. It has a nominal access time of 16mS and can transfer data at up
to 5.0 Mbytes per second.
The drive circuit board contains the drive control electronics and a hard disk
controller. A preamplifier for the read/write circuitry and an optical encoder are
located underneath the drive cover.
The drives feature an on-board media defect and error recovery scheme which is fully
user transparent.
Jumpers
Four jumpers on the drive circuit are used to configure the drive. These are shown,
properly configured, in the following illustration.
The jumpers are labelled CS (Cable select), DS (Drive select), SP (Slave present) and
DM (Drive Mode). The DS jumper must be fitted and the CS, SP and DM jumpers not,
in order for the drive to function in an LS Pro.
Drive format
The physical format of the drive is as follows:
Disks
Heads
Tracks
Formatting
These drives are low level formatted during manufacture. This format has been
optimized to allow the drive to provide maximum performance. Standard low level
formatting programs can only reduce the performance of the drive.
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