Path: utzoo!utgpu!watmath!isishq!f171.n221.z1.FIDONET.ORG!izot
From: izot@f171.n221.z1.FIDONET.ORG (Geoffrey Welsh)
Newsgroups: comp.sys.cbm
Subject: Re: Zmodem implementations
Message-ID: <1854.2423BBF8@isishq.FIDONET.ORG>
Date: 13 Mar 89 22:58:57 GMT
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 > From: elg@killer.Dallas.TX.US (Eric Green)
 > Message-ID: <7509@killer.Dallas.TX.US>
 
 > I wouldn't be so saguine about the perfection of simultaneous IEEE-488
 > and RS-232. I have tried out both the C-Link II and IEEE Flash and
 > found that if you do not disable the RS232 NMIs before doing disk I/O,
 > you will occasionally get a garbled character from the disk.
 
   The one and only reason why Steve Punter's BBS64 (in my opinion by far the 
best C64 BBS program) works only with IEEE-488 drives is that it makes no 
effort whatsoever to arbitrate in some way between disk and modem I/O. It 
thinks nothing of reading a line from a message file, dumping it to the 
buffer, and going immediately for the next line. That is why BBS64 looks so 
much smoother than BBS programs that work with serial drives.
 
   Although it's easy to trip up the RS-232 on BBS64 at 1200 and 2400 bps, I 
have never seen it misbehave in the least because of garbled disk reads (and I 
ran a BBS64 system for three years as well as using several for a couple of 
years before that and since).
 
   There is an interesting fact to note here: BBS64 does not work with the 
C64-Link II because of timing problems. It works flawlessly with the BusCard 
II, the original C64-Link, and the G-Link with the new ROMs in it.
 
   I can't help but wonder if the problem lies in timing/code that was 
borderline to begin with, and not the result of massive RS-232-induced 
problems.
 
 > I suspect that the situation would be a lot better with a good IEEE
 > interface (e.g. the Buscard II or the original SKyles Quicksilver),
 > but still wouldn't trust it.
 
   Whoops, sorry. You now know the answer to that one.
 
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