[sebhc] list archive and a specific question

[Dwight K. Elvey]

>From: "Jim Battle" <frustum at pacbell.net>
---snip---
>
>Dave Dunfield has written a cool utility to do this for northstar disk systems, 
>allowing transferring disk images either way and the communication protocol is 
>checksummed to ensure integrity.
>
---snip---

Hi
 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.
When I captured the images, I'd transfer them twice. A file
compare shows any random error. I had no errors in any of the
transfers except on the serial/cassette card H8-5. These
failed at the 9600 baud to transfer complete images. They
had a circuit that used optical isolators that just didn't
make it for this high a baud rate. My program has the option
to select a slower baud.
 It is true that it is possible to get an error. I should have
used the checksum from the sectors. This would eliminate any
errors caused by bad RAM or by RS232 problems. The only time
I ever saw errors on a serial was in an especially noisy
environment that had a number of large blower motors that
would turn on and off periodically. In this case, we changes
to an isolated RS485 signals and didn't have any more issues.
Dwight


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