[comp.sys.mac] SCSI-dispatch problem

pete@titan.titan.rice.edu (Pete Keleher) (12/19/88)

Before you all say it, I'll say it.
I SHOULD GET A NEW MACHINE. That out of the way, I'll just say in my
defense that I AIN'T GOT THE BUCKS!!!

My problem is that every so often, my mac gets hung. By using TMON,
I can see that it seems to be looping in some code labeled scsi_dispatch.
The reason that I am having this problem is probably because I am
running system 6.0 on an ORIGINAL mac. The ~1984 mac does has been
upgraded with the 128k roms, and I installed Dove 548s 2meg
memory/scsi upgrade. 

Is there really a differance between the mother board of the Mac Plus
and the origninal that could be causing this problem, or do I just
have bad hardware? Failing an answer for that, has anyone else noted a
similar problem? I am using a CMS MACSTACK 20 disk.

pete pete@titan.rice.edu

jcl@hpausla.HP.COM (Jeff Laing) (12/21/88)

Pete Keleher (pete@titan.titan.rice.edu) writes in comp.sys.mac:
> My problem is that every so often, my mac gets hung. By using TMON,
> I can see that it seems to be looping in some code labeled scsi_dispatch.

Now that you mention it, yeh.  I do have the same problem 'from time to time'
Loops in the same place every time (waiting for a bit to get set in scsi_disp)
Running disk tests claim that the disk media is ok

> The reason that I am having this problem is probably because I am
> running system 6.0 on an ORIGINAL mac. The ~1984 mac does has been

I'm not. I'm still on 4.3 (I don't trust these fancy new systems yet) on
a Mac+ with 2.5 meg.

> have bad hardware? Failing an answer for that, has anyone else noted a
> similar problem?

I had put it down to the fact that I am running a no-name drive (constructed
by one of the local computer store hardware hackers, probably from a Seagate)
I have already had to make one change to the driver he wrote (he managed to
have a word being accessed at an odd address).  My guess was that the drive
does not really support blind read/writes properly, and its getting behind
just long enough to hang...

Anyone got any ideas?

ts@cup.portal.com (Tim W Smith) (12/23/88)

Have you tried calling Dove and asking if there are comparibility
problems with that hard drive?  They had to do some interesting
things to get a SCSI port on the old Mac, and some software that
manipulates the SCSI chip directly rather than going through
the SCSI Manager can have problems.

					Tim Smith