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Path: utzoo!watmath!clyde!rutgers!cbmvax!grr
From: grr@cbmvax.UUCP
Newsgroups: comp.arch
Subject: Re: Using a DMA chip in strange ways
Message-ID: <1429@cbmvax.cbmvax.cbm.UUCP>
Date: Wed, 18-Feb-87 02:14:42 EST
Article-I.D.: cbmvax.1429
Posted: Wed Feb 18 02:14:42 1987
Date-Received: Thu, 19-Feb-87 18:52:54 EST
References: <4343@columbia.UUCP>
Reply-To: grr@cbmvax.UUCP (George Robbins)
Distribution: world
Organization: Commodore Technology, West Chester, PA
Lines: 15

In article <4343@columbia.UUCP> dupuy@amsterdam.columbia.edu (Alexander Dupuy) writes:
>
>    Since the DMA chip on your favorite disk/tape controller works by stealing
>bus cycles when the CPU is busy with other things (like arithmetic), would
>there be any advantage in having a DMA chip which would simply be used for
>memory to memory copies (from user to kernel space, or from one user space to
>another)?

Many general purpose DMA controller chips can already do this sort of thing.
Other, fancier things like BLIT chips can also to high-speed memory to memory
DMA as a degenerate case.
-- 
George Robbins - now working for,	uucp: {ihnp4|seismo|rutgers}!cbmvax!grr
but no way officially representing	arpa: cbmvax!grr@seismo.css.GOV
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)