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Date:      Wed, 11 Oct 1995 12:50:16 +0930 (CST)
From:      Michael Smith <msmith@atrad.adelaide.edu.au>
To:        terry@lambert.org (Terry Lambert)
Cc:        bde@zeta.org.au, hackers@FreeBSD.ORG, msmith@atrad.adelaide.edu.au
Subject:   Re: non-sio UART driver
Message-ID:  <199510110320.MAA13239@genesis.atrad.adelaide.edu.au>
In-Reply-To: <199510101825.LAA10775@phaeton.artisoft.com> from "Terry Lambert" at Oct 10, 95 11:25:03 am

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Terry Lambert stands accused of saying:
> > What's a multidrop serial bus?
> 
> You know; like an Altos 2000.  8-).

Ah, Terry, off on an historic trip again 8)

Unfortunately, nothing so romantic.  '485 is used lots in industrial 
applications because you can run it insanely long distances in really
noisy environments, and in 9-bit mode writing code for a micro to 
interact with it is trivially easy.

> > If you need to do any normal serial i/o to a 16x50 then I suggest adding
> > to sio.
> 
> It's not; it's a muxed 422/424 connection to multiple uarts in a
> fan-out box.

It's actually a 232 to 2-wire 485 adapter that uses DTR to control the 
drive/listen input on the 485 driver.  It consists of two chips (MAX232
and MAX485) and some jellybeans.

> 					Terry Lambert

-- 
]] Mike Smith, Software Engineer        msmith@atrad.adelaide.edu.au    [[
]] Genesis Software                     genesis@atrad.adelaide.edu.au   [[
]] High-speed data acquisition and                                      [[
]] realtime instrument control          (ph/fax) +61-8-267-3039         [[
]] My car has "demand start" -Terry Lambert  UNIX: live FreeBSD or die! [[



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