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From: bj@well.UUCP (Jim Becker)
Newsgroups: comp.sys.amiga
Subject: Re: Hard disk through parallel port
Message-ID: <2241@well.UUCP>
Date: Sun, 21-Dec-86 02:58:50 EST
Article-I.D.: well.2241
Posted: Sun Dec 21 02:58:50 1986
Date-Received: Sun, 21-Dec-86 06:35:47 EST
References: <634@hp-sdd.HP.COM> <1121@cbmvax.cbmvax.cbm.UUCP> <1527@ulysses.ho
Organization: Whole Earth Lectronic Link, Sausalito, CA
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mer.nj.att.com>
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Reply-To: bj@well.UUCP (Jim Becker)
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Organization: Whole Earth Lectronic Link, Sausalito CA
Keywords: hard disks, DMA, AmigaDOS

In article <1527@ulysses.homer.nj.att.com> eric@ulysses.UUCP (Eric Lavitsky) w
rites:
>>George Robbins (cbmvax!grr) Writes:
>>Well, since there is no DMA support available for the Parallel Port, the
>>actual data transfer part of the disk activity will be slower than a DMA
>>type disk controller attached to the Expansion Bus.
>
>A bit of clarification here: George is correct, but: The only thing DMA
>really buys you on the Amiga currently, is the fact that data trasnfers
>don't interrupt the CPU. The maximum *actual* throughput for current DMA 
>vs. non DMA disks is currently limited by AmigaDOS, which can only chug 
>through about 35K/Sec. So, a disk on the parallel port, if designed correctly
,
>will get you at least close to that limit and a DMA disk cannot surpass
>that limit (at least not the ones that currently exist). Of course, if
>you're not using AmigaDOS, that's another story...
>
>Has anyone used the disk benchmark recently posted by Rick Spanbauer on
>some of the popular Amiga hard disks?
>
>Eric


Eric,

I know that you are int the know, but in this case you are incorrect. the DMA
is much faster than what can happen on the parallel port. What transpires on
the expansion bus if difficult to get used to, although one adapts to the speed
in time and cna await the 2 to 3x speed improvement in the DOS that is coming.

The Parallel port doesn't have DMA, but the serial port does. Noone has tapped
this yet though. It will be inconsiquential though, when the Pal Jr comes out
there will be a new standard that will take a while for the human to get 
used to, especially with InfoMinder Plus.

Amiga will be the future, espiecially if C-A realizes it.

-Jim Becker
Terrapin Software