[sebhc] list archive and a specific question

Dwight K. Elvey dwight.elvey at amd.com
Wed Jul 6 17:06:42 CDT 2005

Hi Dave
 If you are seeing errors, you have some type of
issue that needs to be fixed. Are you using the
checksum directly from the sectors on the disk
( may be a CRC ) or are you generating it from
a RAM buffer? Like I said, I've never seen a problem
without a cause. I have designed embedded systems
that do CRC checking on packets of data that
run continuously, 24/7. Any logged errors required
repairs. I've, also, done over a 100 disks on my Poly8813 without
a single missmatch.
 In any case, you should try using a CRC rather than
a check sum. These can be used to find the error location
for small burst of bit errors. I would suspect your RAM
if the errors were always in the same location of your
buffer. As a sanity check, you might try turning on
the parity as well.
 Of course, if you are using Windows, such errors are normal.

>From: "Dave Dunfield" <dave04a at dunfield.com>
>> I thought I'd mention, I don't do checksum. My experience with
>>serial is that it is either working or it is not working.
>I've been slowly "mining" a box of about 1000 NorthStar disks...
>So the Vector is often sitting here sucking on a diskette and
>sending it up to the PC. My PC software tells me when it gets a
>soft communications error (checksum failure), and I do see them
>occuring from time to time - often enough that I would not want
>to ignore the possibility.
>dave04a (at)    Dave Dunfield
>dunfield (dot)  Firmware development services & tools: www.dunfield.com
>com             Collector of vintage computing equipment:
>                http://www.parse.com/~ddunfield/museum/index.html
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