Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!sun-barr!newstop!texsun!convex!swarren
From: swarren@convex.com (Steve Warren)
Newsgroups: comp.sys.amiga
Subject: Re: A2630 questions (for Dave Haynie this time) [REPOST]
Keywords: A2630
Message-ID: <-1773786386@convex.convex.com>
Date: 16 Feb 90 16:20:52 GMT
References: <1251@crash.cts.com> <9442@cbmvax.commodore.com> <1277@bmers58.UUCP> <1287@bmers58.UUCP> <9696@cbmvax.commodore.com>
Sender: usenet@convex.com
Organization: Convex Computer Corporation; Richardson, TX
Lines: 41

In article <9696@cbmvax.commodore.com> daveh@cbmvax.cbm.commodore.com (Dave Haynie) writes:
>In article <1287@bmers58.UUCP> keithh@atreus.UUCP (Keith Hanlan) writes:
                            [...]
>>	o What is the difference between AddMemed memory and 
>>	  Autoconfig memory to a DMA device?
>
>Autoconfig memory is memory that supports the Amiga AUTOCONFIG(TM) protocols
>and is automatically recognized and added by the Amiga's expansion.library.
>AddMemed memory is manually added at a hardwared memory location, usually a
>line somewhere in your Startup-Sequence if you have such memory.  By the
>rules, any device in the $00200000-$009FFFFF range MUST be autoconfiguring,
>and any device that doesn't autoconfigure MUST be located outside of that
>range.  That puts extra 32 bit memory outside of the 68000's address space,
>since there isn't any other space available to add-ons in the 68000 address
>space.  So if you follow the rules, on A2500/xx and below, all autoconfigured
>memory will be accessible by DMA device, no AddMemed memory will be.
                            [...]
Dave,

Is this just because the controller can't get to the 'extended' address
bus bits for 32-bit processors?  If so then the distinction would appear
to be location in the address mapping, not addmemed/non-addmemed (oh yes,
you did mention that this applies for systems that follow the rules.  Is
it illegal to have non-autoconfig devices within the 68000 address space?).

I am not making light of the "rules", I am just trying to make sure I
properly understand how they apply.  I assume that DMA would be possible
via an extended bus connection?  Perhaps by running an address-cable
with the extra bits directly to the card in question?  That would allow
DMA to an AddMemed memory card.  Would that be a problem?

BTW, I would have redirected this to comp.sys.amiga.hardware, but this
group still hasn't shown up at our gateway, and then I wouldn't be able
to read the response.  Who invoked the new group, and why are some of
us still not getting it?  If it was done right it should show up
automatically, right?

--
--Steve
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