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From: ddl@husc6.harvard.edu (Dan Lanciani)
Newsgroups: comp.periphs.scsi,alt.cd-rom
Subject: NEC CDR-72 help
Message-ID: <6834@husc6.harvard.edu>
Date: 21 May 91 03:31:22 GMT
Article-I.D.: husc6.6834
Followup-To: poster
Organization: Harvard University, Cambridge MA
Lines: 21


	I have a NEC "Intersect" external CD-ROM drive connected to
a 386SX clone by NEC's (Trantor's) host adapter.  Lately, I noticed
data corruption (try to install new MSLIB and the damaged .EXE crashes;
simply copy a set of files from the CD-ROM to hard disk and the copies
differ from the originals).  The drive is about 6 months old and
the problem is (I think!) new.
	After examining the files more closely, I find that the corruption
always consists of a 2k block (on a 2k boundary) whose contents are those
of the previous block rather than what they should be.  In other words,
a block is replicated and a block is lost for no net change in file
size.  Does this sound familiar to anyone?  I dread the task of convincing
NEC tech support that something is wrong.  Are there any diagnostic
programs around?
	The only explanation I could come up with is that a read error
occurs and the error-recovery logic in the Microsoft CD file system
re-reads the wrong block.  In any case, this kind of undetected error
seems a little scary...

				Dan Lanciani
				ddl@harvard.*