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HARDWARE ________________________________________________ ___
RIGID DISK STORAGE
A rigiQ disk can store much larger volumes of information
than noppy disks. And physical structure and speed of the
rigid disk gives you significantly faster data transfer rates.
The recording of data onto and retrieval of information from a
rigid disk is very similar to the process for a floppy disk. The
main differences are that the rigid disk is made up of two hard
surface platters and has four read/write heads-one for each
side of the two platters, as shown in the illustration to the
right.
An 8" floppy disk drive is included with the rigid disk drive unit to provide compatability (read a disk from
another 820-11 and read software programs purchased on floppy disks). In addition, the 8" floppy disk can
be used to make back up copies of the information stored on the rigid to guard against accidental data loss.
When the rigid disk is initialized (formatted), it is divided into
sectors and tracks much like the floppy disk. Each platter of
the rigid disk will have 256 tracks and each track will have 32
sectors. Each of the sectors can hold 256 characters, so the
entire disk can hold over
8
million characters.
You could use the disk as one big
8
million character disk. Or you could divide the disk into segments so that
you can store letters in one segment, a lengthy data base in another segment, all your programs in a third,
etc.
The 820-11 will automatically divide the disk into four segments (called partitions) containing 4 million
characters, 2 million characters and two segments of 1 million characters each. If this partitioning does not
meet your needs (perhaps you have a data base larger than 4 million characters), you can change the
partitions using the CONFIGUR program provided by Xerox. See your Reference Manual for details.
The four positions are referred
to as E, F, G and H.
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