Newsgroups: comp.protocols.tcp-ip
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: TCP/IP on MIDI?
Message-ID: <1989May6.213417.20756@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1989May3.180345.6936@utzoo.uucp> <4076@ficc.uu.net>
Date: Sat, 6 May 89 21:34:17 GMT

In article <4076@ficc.uu.net> peter@ficc.uu.net (Peter da Silva) writes:
>MIDI is one-way... there's no return path for acks. Why not just leave the
>MIDI adapter out of the loop and run the baud rate up on your RS232 SLIP?
>(one reason a fast serial port that can be trivially adapted to MIDI levels
>is more useful than a dedicated MIDI port.)

The one-way issue is solved by forming a ring.  (Although the once-around
delay on the ring will be substantial, which is one reason why I asked if
anyone had tried it yet -- most ring networks I know of run at rather higher
speeds.)

As for RS232, a fully-RS232C-conforming driver cannot in fact run much
faster than 20 kbps (vs. MIDI's 31250) reliably.  Read the fine print about
slew rate.  Older driver chips often don't limit the slew rate properly
and can be pushed to higher rates under good conditions, but newer chips
(like the MAX232) follow the standard.  With short cables and a favorable
phase of the moon they'll sometimes run at 38400, but that's about it.  To
get reliable serial transmission at speeds much higher than MIDI, you need
to abandon RS232 anyway.
-- 
Mars in 1980s:  USSR, 2 tries, |     Henry Spencer at U of Toronto Zoology
2 failures; USA, 0 tries.      | uunet!attcan!utzoo!henry henry@zoo.toronto.edu