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From: koziol@yoyodyne.ncsa.uiuc.edu
Newsgroups: comp.sys.ibm.pc
Subject: Re: Automatic disk compression (har
Message-ID: <17200001@yoyodyne>
Date: 6 Jun 90 02:35:00 GMT
References: <19500071@uxh.cso.uiuc.edu>
Lines: 48
Nf-ID: #R:uxh.cso.uiuc.edu:19500071:yoyodyne:17200001:000:2245
Nf-From: yoyodyne.ncsa.uiuc.edu!koziol    Jun  5 21:35:00 1990


I saw this article in this months issue of Byte (p.44):

DOUBLE YOUR DATA STORAGE CAPACITY WITH $199 CARD
The InfoChip Expanz! is a compression coprocessor card with a proprietary
chip that compresses data on random-access data storage devices, such as 
floppy and hard disk drives.
	Expanz! offers transparent compression and decompression and does not
slow down your access to the stored data, the manufacturer says.  The method
of compression is "lossless" as compared to video compression, where a certain
amount of data can be lost but is not noticeable when you look at the
compressed and decompressed video.
	The 8-bit half-length Expanz! will work with any DOS 3.x application and
averages a 2.5-to-1 compression ratio.  That means that your 20-MB hard drive
will hold about 50 MB of data, and your 100-MB SCSI drive will hold 250 MB.
The overhead for compression on a hard disk averages 3 percent of the size of
the original hard drive, or less than 1 MB in the case of a 20-MB drive.
	Once you have Expanz! installed on your XT or AT and you are ready to
compress the files on your 20-MB hard disk drive, the compression process takes
about ten minutes.
	Thereafter, Expanz! will compress and decompress files as you use your
computer.  And because you are them reading compressed files (e.g., three 
sectors of the disk now map to one), the read time is somewhat faster than it
was with uncompressed files.  The time will not be substantially less for hard
disk drive reads, but floppy disk drive reads are said to be about three times
faster.

PRICE: $199
CONTACT:	InfoChip Systems, Inc.
			2840 San Thomas Expy.
			Santa Clara, Cal.
			95051
			(408) 727-0514

=============================================================================
I haven't called them yet, but some of the information I would like to know
would be:	What about DOS's 32MB drive partition, how does their card deal
with large drives, etc..?  What about caching disk controller cards, how are
they dealt with?  Is their some way to uncompress your data again (say to
distribute a floppy to someone without this card)?
	If they can deal with these potential problems realistically, I may pick
the card up.

Quincey Koziol
Programmer
NCSA

koziol@ncsa.uiuc.edu