Date   : Wed, 02 Mar 1983 08:04:56-MST (Wed)
From   : David Keaton <keaton.nmt@rand-relay.arpa>
Subject: Error checking

     I have written some software (Z80 assembly code) that checks what comes
back from the host to make sure it's valid.  I'll be glad to send it to anyone
who wants it -- it's pretty short (or I'll post it to Info-CPM if there's
enough interest).  It may take a while though because I have to wait for my
computer to come back from the factory -- it's an Osborne-1 getting a double
density upgrade.
     I do have an observation though:  I seem to get fewer errors when I turn
off echo at the host and use checksums.  I'm not sure whether this is because
of some kind of feedback in the phone lines (anybody know if that's possible?)
or just that my micro is slow in receiving characters when it's trying to
send them at the same time.  My gut feeling says it's the latter.
     I have been playing around with calling bigger machines with my micro
for four to five months now and have NEVER had problems with the bit rate
affecting my error count (i.e. 1200bps is as reliable as 300) and this includes
long-distance phone lines.  Before I got my modem, I heard people complain
about 1200bps being unreliable all the time.  Am I just lucky or do the rest
of you have the same experiences?

                                David Keaton
                                keaton.nmt@Rand-Relay