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From: visinfo@ethz.UUCP (VISINFO c/o Sascha Schnapka)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: A2000 HD controllers opions and or help
Keywords: GVP Controller
Message-ID: <4385@ethz.UUCP>
Date: 7 May 90 12:12:49 GMT
References: <2035@dsacg2.dsac.dla.mil> <26220131.7262@paris.ics.uci.edu> <02209.AA02209@babylon> <262B5876.10938@paris.ics.uci.edu> <2260@eklektik.UUCP> <2633E370.20045@paris.ics.uci.edu>
Reply-To: visinfo@bernina.ethz.ch.UUCP (VISINFO c/o Peter Simeon)
Organization: ETH Zuerich, Switzerland (Peter Simeon)
Lines: 33

In article <2633E370.20045@paris.ics.uci.edu> lgulyas@ics.uci.edu
(Laszlo Gulyas) writes:

>Here are my latest results with the GVP Impact SCSI + 8 and the ST296N
>If I reformat using GVPFormat at 1:1 (their software) I get a max of 190K
>with the DiskSpeed program.
>If I reformat at 2:1 I get a transfer rate of 180K.
>At 3:1 the rate goes down by a few K.
>
>I wonder if the autoboot ROMs are the problems?
>What is the optimum buffer size, as I have 2megs of SIMMs on the board.
>and memory is not a problem.

I suppose that your drive is so slow because of the MaxTransfer bug in the
GVP install software 'GVPprepHD'. They let you set the MaxTransfer to the
maximal number of 8192. This means that the scsi.device can only handle
8192 per request. This limitation was caused by a mistake in the original
AmigaDOS 1.3 manual. They have written that this entry means number of
blocks.
You can go around this problem by patching the RigidDisk block with the
partition description (beginning with PART). If you have the C include files
you can look at the structure definition in the file 'hardblocks.h'. You have
to correct the checksum as well. (It is a sum up to zero).
You should set the MaxTransfer entry to 131072. This should nearly double
the transfer speed. If you have a 68020 or a 68030 the effect is even better.
To try out the MaxTransfer you can also mount your partition with another
name and make speed tests.

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