Path: utzoo!attcan!uunet!cbmvax!valentin
From: valentin@cbmvax.UUCP (Valentin Pepelea)
Newsgroups: comp.sys.amiga.tech
Subject: Re: DMA in VM
Message-ID: <8800@cbmvax.UUCP>
Date: 3 Dec 89 08:14:35 GMT
References: <14059@grebyn.com> <838@tardis.Tymnet.COM> <14068@grebyn.com>
Reply-To: valentin@cbmvax.UUCP (Valentin Pepelea)
Organization: Commodore Technology, West Chester, PA
Lines: 20

In article <14068@grebyn.com> ckp@grebyn.UUCP (Checkpoint Technologies) writes:
>
>It happens that the 68851 PMMU, as used in the A2620 card, has just that
>feature: a separate page table for a DMA device. It may be remotely
>possible to press this into service in the Amiga, but I doubt it.

The 68851 MMU resides between the main processor and memory. If a DMA device
wanted to access the memory through the MMU, it would have to be sitting on the
same side as the processor. Obviously impossible.

>However, the 68030's built-in PMMU doesn't have this feature, ...

For obvious reasons.

Valentin
-- 
The Goddess of democracy? "The tyrants     Name:    Valentin Pepelea
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