Date   : Wed, 25 Aug 1982 00:00:24-EDT (Wed)
From   : Keith Petersen <w8sdz@BRL>
Subject: [Ted Shapin: MODEM221 Overrun Problems]

This was sent to Info-Micro instead of Info-Cpm.  I am forwarding
it to save Ted the trouble of retyping the message.  Replies to
address below, please...


----- Forwarded message # 1:

Mail-from: DECNET site ECLD rcvd at 24-Aug-82 1840-PDT
Date: 24 Aug 1982 1837-PDT
From:  Ted Shapin <BEC.SHAPIN.USC-ECLD@Usc-Ecl>
Subject: MODEM221 Overrun Problems
To: info-micro at Brl
cc: BEC.SHAPIN.USC-ECLD at Usc-Ecl
Mail-Address: 2500 Harbor Blvd., Fullerton, CA 92634
Phone: (714) 970-3393
Via:  Usc-Ecl; 24 Aug 82 21:44-EDT
Via:  Brl; 24 Aug 82 21:49-EDT
Via:  Brl-Bmd; 24 Aug 82 21:56-EDT

I have been fixing some things in MODEM TOPS20 and experienced the same
inability of MODEM221 to recover after receiving 80H sectors and giving
an overrun message.  That is 16K on the CP/M disk and CP/M BDOS needs to
get another extent and takes more time before it is ready to receive.

Operating at 1200 baud, I get this error every time regardless of how
lightly or heavily my DEC system is loaded.  MODEM221 doesn't recover;
but an earlier MODEM207 does - - it gives one error message and gets
back in sync.

Ted.

P.S.  On MODEM TOPS20 it is necessary to turn off pause on command and
pause on end of page, otherwise block 13H is treated as an X-OFF and will
stop transmission from the TOPS system.  One of the mods I made is to set
this automatically on entry if the logged terminal is the one that is
connected to the modem.



----- End of forwarded messages