At 23:19/29/Mar, John McAlpin (1:382/1202) said:
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JM> Hello All,
JM> I have a USR Courier VEverything (recently upgraded to v.90 without a 
hitch 
JM> - and I was having the problems described below before the update) and am 
JM> having problems with a BBS downlink of mine using a V.34 Zoom.  He's also 
JM> using an OS/2 mailer called Adept.  Anyway, we connect fine and transfer 
JM> files fine. Except that he's having problems receiving larger files 
JM> (greater than around 70kb).  We get a CRC error, it attempts a restart at 
JM> 256 then disconnects. And this can go on for a while with a 5mb file.
CRC errors occur between the com port and your comm application - the modem 
isn't involved.  The usual cause is a delayed interrupt - an interrupt 
generated by the UART that is not serviced quickly enough.  The error is 
detected by the file transfer protocol, and any remedial action is determined 
by the comm app that's running.
JM> How can I get my Courier to re-start transfers with the Zoom modem after 
JM> CRC errors?  The Hayes can do it?  And, if it's the modems how come he 
can 
JM> log on my BBS and it'll restart after CRCs?  Odd.
Your problem is with the mailer config, not the modem.  THe modem doesn't 
know a CRC error occurred, doesn't know anything about block sizes, and 
doesn't care.
You might try _reducing_ the size of the 16550 UART buffer.  That makes a 
longer interrupt delay possible and lessens the chance of a CRC error.
Rick
--- Msged 4.00
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