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From: ford@amix.commodore.com (Mike "Ford" Ditto)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: What Happens If You Have > 9 Meg??
Summary: Get an A3000
Message-ID: <890@amix.commodore.com>
Date: 23 Jan 91 09:10:04 GMT
References: <7016@crash.cts.com>
Reply-To: ford@amix.commodore.com (Mike "Ford" Ditto)
Organization: Commodore-Amiga Unix Development
Lines: 24

In article <7016@crash.cts.com> lkoop@pnet01.cts.com (Lamonte Koop) writes:
>>The biggest problem that you face is the lack of address lines for that
>>much ram.
>
>No.  The 68000 can physically address up to 16 megabytes of RAM.  This does
>include memory used by
>any I/O devices and such on the bus, as the 68000 does use memory mapped I/O. 

So the problem *is* the number of address lines:  All the 16 Meg space
has been allocated (look at the Amiga Expansion Specifications), and
there are no more address lines on the Zorro II bus.

>The limiting factor here is AmigaOS, which limits _AutoConfig_ memory boards
>to a total of 9.5 megs, regardless of the 68000's 24-bit address space.

It's not the software but the AutoConfig hardware spec that specifies
the range of addresses for AutoConfig memory boards.  Unix, for
example, is subject to the same limits.

					-=] Ford [=-

"Goodbye, goodbye, goodbye, goodbye,	(In Real Life:  Mike Ditto)
 goodbye, goodbye, goodbye."		ford@amix.commodore.com
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