Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!cs.utexas.edu!uunet!cbmvax!jesup
From: jesup@cbmvax.UUCP (Randell Jesup)
Newsgroups: comp.sys.amiga
Subject: Re: Info Recommendations on system
Message-ID: <7471@cbmvax.UUCP>
Date: 28 Jul 89 21:01:37 GMT
References: <1350@amigash> <419500002@S67.Prime.COM>
Reply-To: jesup@cbmvax.UUCP (Randell Jesup)
Organization: Commodore Technology, West Chester, PA
Lines: 25

In article <419500002@S67.Prime.COM> CFW@S67.Prime.COM writes:
>Note that the disk uses an AT driver - it is not a SCSI device.
>
>Seems to work just fine, although I discovered a problem with the max
>transfer rate of the disk's AT driver.  Seems that it wasn't being set
>at all, and this caused problems because the drive loaded data TOO FAST
>for some software (like DPaintIII 3.1) to handle it - it hung the system.
>GVP has a fix for this (they told me this on 7/26/89) and will be shipping
>out new drivers to registered owners with the max transfer rate set to 128K.

	A bit of confusion - your problem was with the maximum transfer SIZE,
not speed.  It sounds like their driver isn't smart enough to break
transfers too large for their DMA chip into mutliple transfers.  This causes
large reads/writes to fail.  Dpaint has VERY large hunks in the load file
(greater than 128K), so attempts to read the hunk fail.  They're probably
using a DMA chip with 64K words (128K bytes) maximum transfer size.

	This is a distressingly common error among HD driver writers, and
even caused us to add a MaxTransfer setting for FFS to keep it from making big
requests of the driver.

-- 
Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.cbm.commodore.com  BIX: rjesup  
Common phrase heard at Amiga Devcon '89: "It's in there!"