A4091 Controller
13 messages in this thread
Many and many a year ago I bought a CBM PET 8032 and a dual disk drive
(4050?). The drive used the HPIB (IEE488) bus. The cable to connect
the two was not included. It cost an extra $50. Nobody mentioned it
when I ordered the system.
Well I did some checking today on the external SCSI-II connector
and hopefully will have that problem resolved. I ordered a high
density DB-50 to standard SCSI-50 cable. Since I'm building a tower
case for all my external drives, this should work out. Actually, it
wouldn't be too hard to make a DB-50 SCSI-II to DB-25 SCSI adapter if
I could just get my hands on the high density DB-50 connector.
Which brings me to a question for you SCSI guru's. While looking at
the pinout for the DB-50 external connector on the 4091, something
doesn't seem right. If it is truly SCSI-II then shouldn't it have
more than a 8-bit data bus, like 16 or 32? Here is the pinout and
maybe you can see what I'm talking about:
Pin's 1-25 are ground with except for pin's 12 & 14 reserved, and
pin 13 open. Pins 26-33 are /DB0-DB7, and then the rest are other
SCSI command and handshaking lines. The only data path is DB0-DB7.
Now I don't know that much about the SCSI-II spec, but it sure looks
like regular SCSI to me. Which brings another question of why they
used a DB-50 external connector if it is just regular SCSI specs?
Maybe it's a misprint in the manual, but if it isn't, then I would
like to hear from someone on how they are managing SCSI-II with such
an arrangement.
SCSI-II is only 8 bit. It is backward compatible with SCSI-I.
SCSI-WIDE is SCSI-II with 16 bit transfer.
Well like I said, I don't know very much about the SCSI-II spec so
wasn't sure whether or not it was 8-bit. So how are they doing the
claimed 10MB/s transfers, through more efficient handshaking?
To everyone to update you on the continuing saga. I found out
through Gold Service today that the 4000 is NOT covered through them
for the motherboard replacement for the Super Buster chip. According
to the Gold Service representative, since the 4000 is not actually
broken, but rather is just incompatible with the 4091, it is not
covered under Gold Service. Makes a lot of sense, eh? To me, the
4000 is broken since it doesn't work with a card designed for the
4000 in the first place. But I guess my logic and CBM's doesn't
match. I tell you, I'm about fed up with CBM and their lousy
attitude. Maybe I should just fry one of the chip's in the 4000.
Then I could probably get a new computer in a couple of days <g>.
So I'm in the process of trying to get a new motherboard through
our local repair center 160 miles away. BTW, he told me that because
of CBM's lack of support, they are just about ready to drop CBM
servicing also. So that's where I'm at right now. How long it will
take the service center to get a motherboard replacement is anyone's
guess, but I would be surprised if it was anytime soon.
John,
how much did you pay for the A4091 ?
Regards, J0RGEN ….from DENMARK
The 4091 was $319 US from Tenex. Safe Harbor was selling them for $299
but didn't have any in stock. Creative Computers hadn't even heard of
it yet <g>.
John,
A word of caution about the idea of a 25/50 adaptor for the SCSI-II to I
cables. Cheap SCSI cables use only 18 wires by running all the grounds to
a common wire and sometimes shoring that wire to the connector shell.
This apparently works great in the MAC world, but those same cables in
most Unix and Amiga environments will give you no end of problems. Spend
the extra bucks, get the sheilded 50 conductor stuff for the SCSI II,
otherwise you'll regret it.
wmc – via Autopilot!
John,
Perhaps someone could correct me if I'm wrong, but I believe that SCSI-II
uses an 8-bit data path, while Wide SCSI-II would implement a 16-bit data
path.
//Jonathan,
\\//via AutoPilot
As I understand it (and the standard is just now or not quite yet
finalized) there is SCSI-II and SCSI-II wide. The WIDE does a 16 bit
parallel transfer whereas the II plain is 8 bit, I think. (gotta go back
to the research center…[aka library])
wmc – via Autopilot!
SCSI-II is always parallel transfer. SCSI-II can be 8, 16, or 32 bits
wide. 16 bits wide requires a different cable and connector. 32 bit wide
requires both the different connector and the original on two cables with
VERY fancy software handling the timing skew in the cables.
{@_@}
The drive was an 8050 – and those IEEE cables were awfully expensive! But I
did love that 8032.
Betty
Oh, yeah. It was a great machine. Especially after I found the program that
would fool it back into being a 40 column machine to run PET games. Amazing how
well that little program worked too. But I never did find a decent
telecommunications program for it.
—–Paul—–