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From: asd@mace.cc.purdue.edu (Kareth)
Newsgroups: comp.sys.next
Subject: Re: DMA Channels: Where'd they go?
Keywords: dma
Message-ID: <5615@mace.cc.purdue.edu>
Date: 25 Sep 90 23:04:04 GMT
References: <5593@mace.cc.purdue.edu> <50950@brunix.UUCP> <5606@mace.cc.purdue.edu> <14638@cbmvax.commodore.com>
Organization: Purdue University
Lines: 20
Cc:

In <14638@cbmvax.commodore.com> daveh@cbmvax.commodore.com (Dave Haynie) writes:
>In article <5606@mace.cc.purdue.edu> asd@mace.cc.purdue.edu (Kareth) writes:

>>One of the guys here suggest that he believed that the missing channels
>>were due to the fact that the MMU, FPU, and cache which are all on the
>>040 now.

>My uninformed guess would be that NeXT considered each empty expansion bus slot
>to be a separate DMA channel from their DMA controller's viewpoint.  Since the
>"slab" doesn't have these slots, it would be missing 3 channels.  But that's
>really just a guess...

Well, there are 4 missing in the slab.  Your assumption doesn't hold
much water because there are still 4 expansion slots (well, three, if
you don't count the cpu slot), on the cube still, and yet there are 3
missing DMA channels?

Thanks for trying, but no go.

-k