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DISKSQ.DOC
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1985-04-11
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Graham Systems Disk Sqeezer Utilities
Disksq.com and Diskunsq.com are programs which allow a dos 8 or 9
track disk either single or double sided to be compressed into a
DOS file which can then be sent easily over communications lines
or stored in its compressed format. The algorythm which cpmpresses
the disk acts on strings of recurrent characters. It squeezes
from 4 to 256 repeating characters into 3 characters. This
represents aan average compression of 50% to 60%. In order to
make sure that unused portions of a disk are composed of repeating
characters and therfore compressable a small program is included
with Disksq and Diskunsq called Cleandsk.com. Cleandisk will clean
up the unused sectors of a disk so that they can be squeezed more
efficiently.
Using Disksq and Diskunsq:
The command format for Disksq is DISKSQ X: Y:FILE.EXT where
X is the disk to be squeezed, Y is the disk which will store
the squeezed disk file and FILE.EXT is a valid dos name
for the squeezed file. Double sided 9 track disk take about
220k to 260k for full disks. Make sure that there is enough
room on the receiving disk.
Make a note of the disk format. You will need to have a similarly
formatted disk to restore the file. (Disksq assumes that all disks
that it can't identify are 8 track single sided).
I would suggest that you include the disk format in the filename
using the following convention: DISK-TS.DSK where DISK is the
the disk name, T is the number of tracks and S is the number of
sides. DSK indicates that it is a squashed disk.
The command format for Diskunsq is DISKUNSQ X: Y:FILE.EXT where
X is the disk to be restored, Y is the disk holding the FILE.EXT
of the squeezed disk. Anything on disk X will be destroyed as the
disk is being recovered.
Disk x must match the format of the original disk or a copy is not
possible. A single sided disk may be restored to a double sided
disk but you will wind up with a single sided disk. 8 track disks
cannot be restored to a 9 track disk and vice versa.
Hard disks:
I cannot test the code for sqeezing hard disks, but it is there.
Try it if you have another hard disk with enough free space on it
to make it work.
This product is distributed free of charge except for a few limitations.
The product cannot be changed and copyright notices cannot be removed.
If you use this product in a commercial way you must compensate
me for my time. $5.00 is too little to ask for the hours put in
to developing this product.
Please address any payments or other correspondence to:
Graham Systems
238 Germonds Rd.
West Nyack, NY 10994
thanks