Message-ID:	<357BCC3A.E330B9D@post.comstar.ru>
Date:	Mon, 08 Jun 1998 15:34:18 +0400
From:	Dim Zegebart <zager AT post DOT comstar DOT ru>
Reply-To:	zager AT post DOT comstar DOT ru
Organization:	Comstar Ltd.
MIME-Version:	1.0
To:	Javier Calleja <dismuntel AT apdo DOT com>
CC:	djgpp AT delorie DOT com
Subject:	Re: Questions about interrupt handler and bus AT
References:	<01bd92b7$fc621a00$0100a8c0 AT dismuntel DOT ctv DOT es>

Javier Calleja wrote:

>     2  Could someone give me the AT bus protocol ot tell me where I can find
> it? I need communicate the PC with a ISA card which have a 386 micro, I have
> to build a communication protocol via AT bus, how can I do it?
>

AFAIK, there are several possible ways which you may use to communicate with ISA
device :
1. using port I/O
2. using DMA chanel
3. using mapped shared memory

For example comm card with UART use first method and Gravis Ultra Sound card
using
all three. So, you should obtain documentation from manufacturer of your card to
know how
exactly you can interface with device.
AT bas is totaly hidden from software which runs on CPU, it means you can't
catch
any ISA signals (exept some special cases) from within djgpp programm. All this
low level
stuff performed by 'micro' programm which runs on micro-controller(s) chip which
operate
entire ISA device.
On the over hand, if you need to develop ISA device you should definetely visit
bookstore and buy several books about ISA bus. I'm sure you can find ISA
specification
somethere on Net, but IMHO you need more explanating description on how to
design a real
device not just 'pin-means-what' and 'signal-means-what' paper.

PS. My answer is just a common words, so ask more exact question obout what is
your _TASK_
to get more precise answer.

--
____ ____
|   \   /   Dim Zegebart
____/____

Moscow Russia
WWW - http://www.geocities.com/siliconvalley/pines/7817
DZcomm - comm library for Allegro
Palantir - multitasking kernel for Allegro (based on PDMLWP)

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