Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!usc!zaphod.mps.ohio-state.edu!van-bc!
From: lphillips@lpami.wimsey.bc.ca (Larry Phillips)
Newsgroups: comp.sys.amiga.tech
Subject: Re: speeding up the amiga and hardware hacking
Message-ID: <983@lpami.wimsey.bc.ca>
Date: 5 Jan 90 17:47:25 GMT
Lines: 42
Return-Path: <lpami!lphillips>
To: van-bc!rnews

In <90005.150000NETOPRBH@NCSUVM.BITNET>, NETOPRBH@ncsuvm.ncsu.edu (Brandon Hill) writes:
>I have a couple of questions regarding some hardware projects
>I'm thinking of undertaking.
>
>2)  If I wanted another 8520 type device for my personal use, (i.e.
>    I want some fast bare hardware to mess with while still allowing
>    the rest of the system to multitask without interference)
>    where would be the best place in the memory map to place it?

If the device is truly for your own personal use, ie.  you have no plans to
market it, you are pretty much free to put it in a number of different places,
all of which could work just fine, but which could be 'illegal' and could cause
numerous problems in the more global sense.  Example follows:

When the autoconfig software goes out loking for devices, it looks in the
$E80000 area, and each board found gets placed in successive areas in the
pattern $E90000, $EA0000, $EB0000, and so on. It is quite safe, if you know the
configuration of your particular machine, to use, for example, $EF0000.  Bear
in mind that if you add some future, as yet unspecified device, you may have a
conflict.

>    Configuring the device as a system wide resource isn't necessary,
>    as only a single dedicated application will be using it.

I can't emphasize it too much.. do this ONLY if it is JUST for your machine.

>    There's probably no supported way to add extra hardware, however
>    I'm sure some schemes are safer than others.

Ahh, but there is. It's called autoconfig, and is a way to add hardware
without any conflicts whatsoever, and better, to add it in a way that allows it
to be a system-wide resource.

-larry

--
"Cavett Emptor - Let the talk show host beware!" - Evan Marcus
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|   //   Larry Phillips                                                 |
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