Path: utzoo!censor!geac!torsqnt!lethe!yunexus!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!cs.utexas.edu!uunet!comp.vuw.ac.nz!canterbury!chem194
From: chem194@csc.canterbury.ac.nz (John Davis)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: 32bit DMA lockups (Was: More info on A2091 woes)
Message-ID: <1991Feb4.134725.10@csc.canterbury.ac.nz>
Date: 4 Feb 91 01:03:42 GMT
References: <555376@neabbs.UUCP>
Lines: 34

In article <555376@neabbs.UUCP>, ajbrouw@neabbs.UUCP (ALBERT-JAN BROUWER) writes:
> However, there is a problem with _SOME_ 2630 cards while doing DMA to/from
> 32bit memory. I've determined this through experimentation, and by hearing
> from other people having exactly the same problem (probably including you).
> 
> The problem tends to occur when the harddrive is in full swing DMA transfer,
> unfortunately mostly during writes...
> 
> I've been able to reproduce it with both a HardFrame and a 2090a. A friend
> of mine has the same trouble with a 2090a and a 4.x motherboard. I've
> had my motherboard upgraded from 6.0 to 6.2 but the problem persisted.
> Perhaps redundantly; we both have 2630 cards.
> 
> In a recent query to this group John Veldthuis reported exactly the same
> problem, but amazingly this was with a 2620 and a HardFrame.
>...
> A fix? There is none....

I had exactly the same problem on fitting a 2630 to my rev4.3 b2000 using a 
2090a. A call to CBM revealed it was a known problem, and could be fixed by 
adding a pullup resistor across one IC on the motherboard. It cured the 
problem totally for me (I left it copying a 1.5mb file around the hd for
a few hours to test - no problem whatsoever). As far as I know the
fix _ISN'T_ needed on rev6 boards, but it could well be worth 
checking with CBM anyway (and definitely worth checking on your friends
rev4.x machine)

-----------------------------------------------------------
| o  John Davis - CHEM194@canterbury.ac.nz               o |
| o  (Depart)mental Programmer,Chemistry Department      o |
| o  University of Canterbury, Christchurch, New Zealand o | 
| o                                                      o |
| o  co-sysop AmigaINFO BBS,1200/2400 baud CCITT,        o |
| o           24 hours a day, ph NZ +3-3371-531          o |