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From: hah@isum.intel.com (Hans Hansen)
Newsgroups: comp.sys.amiga
Subject: Re: autoconfig
Message-ID: <594@omepd>
Date: Fri, 24-Apr-87 10:35:54 EST
Article-I.D.: omepd.594
Posted: Fri Apr 24 10:35:54 1987
Date-Received: Sun, 26-Apr-87 01:08:44 EST
References: <1524@zeus.TEK.COM> <6838@watmath.UUCP> <1203@ulowell.cs.ulowell.edu> <1107@tekred.TEK.COM>
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In article <1107@tekred.TEK.COM> joels@tekred.TEK.COM (Joel Swank) writes:
>In article <1203@ulowell.cs.ulowell.edu>, page@ulowell.cs.ulowell.edu (Bob Page) writes:
>> 
>> The whole point of autoconfig is that you don't need DIP switches.
>> ..Bob
>
>No, the whole point of autoconfig is that you don't need addmem. The board
>must know where it resides and tell dos where that is at boot time. You
>still need switches to tell the board where it goes. Otherwise it would
>be set at the factory and unchangeable.
>
>Joel Swank

What really happens is the EXEC during boot poles the AUTO-CONFIG devices
sequentialy and each in turn responds with type of board, memory, SCSI, etc.,
and if there is any RAM the physical size of the RAM.  The EXEC then sends
the board the starting address of the RAM which is latched into a register
and used with a comparator to determine if the board has been accessed.
If a board has something like a SCSI port there are decodes in the AUTO-
CONFIG sequence to allow for the booting of the device handler.  Also
there is a continuation bit that allows more than one type of device or
devices and memory to be on the same board; each in turn will have its
own base address register and compatitor.

Hans