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Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!seismo!rochester!stuart
From: stuart@rochester.UUCP
Newsgroups: comp.sys.atari.st
Subject: Re: CTS/RTS Flow Control Problems
Message-ID: <25969@rochester.ARPA>
Date: Sun, 15-Mar-87 08:50:52 EST
Article-I.D.: rocheste.25969
Posted: Sun Mar 15 08:50:52 1987
Date-Received: Sun, 15-Mar-87 23:48:15 EST
References: <453@ll-xn.ARPA> <25784@rochester.ARPA> <228@mks.UUCP>
Organization: U of Rochester, CS Dept., Rochester, NY
Lines: 25
Keywords: TOS RS232 CTS RTS BBS
Summary: The ST doesn't handle sustained CTS

In article <228@mks.UUCP>, wheels@mks.UUCP writes:
> In article <25784@rochester.ARPA>, I write:
> > The chips that handle the RS-232C interfaces treat these
> > signals as EDGE-TRIGGERED.
> 
> I remember reading that, I think in the Abacus book, but then I also heard
> that was only in the early versions and had been changed for TOS in ROM.

Your source misinformed you.  I have a 1040STf with TOS in ROM.  It
exhibits exactly the behavior I described.  The interface chip is STILL
a MC68901, which is STILL edge-triggered.  You do have your choice of
positive or negative transitions, which is why I said that I thought
the problem was fixable with fancier software (in a nutshell look for
the absence of the negative transition, and keep transmitting).

It may well be that the Avatex and the UR Robotics do not have
significant buffering (they have at least one character of buffering
of course, since the register from which they shift out bits on the
the telephone line is obviously not the register in which they store
the latest character from the ST).  That is a quibble, because the
behavior I described with the sustained CTS signal is not dependent
of modem buffer length, only on the absence of overrun from the host.
Let's not quibble.

Stu Friedberg