Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!samsung!uunet!bnrgate!bnr-fos!bmers58!atreus!keithh
From: keithh@atreus.uucp (Keith Hanlan)
Newsgroups: comp.sys.amiga
Subject: Re: A2630 questions (for Dave Haynie this time) [REPOST]
Keywords: A2630
Message-ID: <1287@bmers58.UUCP>
Date: 1 Feb 90 14:26:51 GMT
References: <1251@crash.cts.com> <9442@cbmvax.commodore.com> <1277@bmers58.UUCP>
Sender: news@bmers58.UUCP
Reply-To: keithh@atreus.UUCP (Keith Hanlan)
Organization: Bell-Northern Research, Ottawa, Canada
Lines: 59

I think this one disappeared somewhere...

daveh@cbmvax.commodore.com (Dave Haynie) writes:
>pierre@pro-graphics.cts.com (Peter Altamore) says:
>>[...]
>...there is a daughterboard connector on the A2630 which
>will logically support the addressing of 64 megabytes of 32 bit memory.
                                          ^^^^^^^^^^^^
	Yeeeeeeeeeee Haaaah! :-)

>> Will peripherals that are on the 68000 bus (in the slots)
>> affect the amount of RAM that the 030 can use?  What will happen if I have 4
>> megs of 16-bit RAM AND 8 megs of 32-bit RAM?  
>
>All of this depends on where things are mapped.
>cards sit there (except for very small I/O typs cards, which have another 
>small space they can live in).  All autoconfig cards live there too.  If your
>32 bit memory is autoconfiguring, it takes away some of the space used for
>16 bit cards.  A bridge card takes up 2 megs.  If you have 8 megs of autoconfig
>memory on an 68030 card, you can't have the bridge card at the same time.
>It's up to the designers if that 32 bit memory can be mapped elsewhere and
>AddMemed.  However, having ONLY AddMemed 32 bit memory will slow down your
>DMA performance with hard disks.  These are what we call trade-offs.

	Dave, I'm a little on the dense (in-experienced) side. Could you
	elaborate this last bit for me please. 
	o What is the difference between AddMemed memory and 
	  Autoconfig memory to a DMA device?
	o Is it possible to autoconfig only, say, 6MB of the 32bit RAM and
	  let an additional device, such as a Bridgeboard or my 2058/2, 
	  use the remaining 2MB of autoconfig space? Is this basically
	  a question of whether or not the manufacturer provides enough
	  flexibility through jumpers?
	o Is there a way to conditional autoconfig different cards
	  depending on whether or not the machine is booted in 68000 mode?
	  That is, say I have the following: A2630/8MB (eventually) and 
	  A2058/4MB:
	  1. In default 68030 mode, I want all the 32bit RAM to be autoconfig
	  and the 16bit RAM to be AddMemed since you imply that the
	  autoconfig RAM is faster for DMA. (right?)
	  2. In 68000 mode, I want the 16bit RAM to be autoconfig since the
	  32bit RAM is unusable. (right?)
	  3. If I can't have (1), can I autoconfig the 4MB of 16bit and only
	  4MB of the 32bit?

>...Commodore also required a 2 megabyte option,
>which does limit a number of the "tricks" you can play with the 68030 to
>make things go a little faster.
	Can you suggest why they imposed this constraint? I concede that it
	certainly makes for a less expensive, (and thus more marketable?),
	board. Is that basically all there is too it or did they insist
	on permitting the completely autoconfig 6MB + 2MB Bridgeboard.

Lovely machine eh guys? 
geez I'm in a good mood today. Love you all...
Keith Hanlan
Bell-Northern Research, Ottawa, Canada 613-765-4645
uunet!bnrgate!atreus!keithh or (via bitnet) keithh@bnr.ca
"You're making me feel wierd Adrian" Jack Carney to Adrian LeDuc, Apartment Zero