C70:info-cpm (07/15/82)
>From FJW@Mit-Mc Wed Jul 14 23:20:29 1982
It turned out that I simply didn't apply the originally suggested fix
in the "right" place. (I put it in the REMSTAT routine.) The problem
with MODEM and friends is the garbage collection that is done after a
block is sent: it does a direct call to REMIN (or more likely in your
implementations, just an IN DPORT), twice. That is where the check of
the xmit buffer was not done. The last character sent, which should
have been the checksum byte in my case, ended up being replaced by the
last character received - the initial NAK!
Thus, the real and normally superfluous fix is to always check the
status of the xmit buffer before reading the receive buffer...
To correct the previous rumor: it is a second-source supplier of the
2661 who is holding orders pending a fix to a "masking problem."
--Frank