Ended auction for qbus SCSI

From: Richard Erlacher <edick_at_idcomm.com>
Date: Mon Jul 9 00:20:41 2001

At Martin, we used an early Emulex single-channel board that was considered
about the least costly. The original plan was to use it to talk to WORM drives
with which we replaced the TK-50, but after we found that the MAXTOR 3380 (later
called 4380S), which was $1k cheaper than the 4380E (ESDI) of which we were
using two, together with an EMULEX ESDI (QBUS) board, which cost about $2300 or
so, we decided we liked the all-SCSI solution. It outperformed the ESDI
approach by quite a little too.

Unfortunately, though several vendors claimed to have SCSI WORM drives, they
were all one sort or another of "modified ESDI," which meant they were all
different but not standard ESDI. Apparently Lockheed had spec'd a form of
nonstandard ESDI for the flight data recorder on the F-16 and they owned a
subsidiary (Cherokee Electronics) that built a WORM drive with that interface.
Although nobody had one working properly at the time, everybody had a version.
We had to build a SCSI<=>ESDI bridge in order to demonstrate the concept.

Not being terribly easy to impress, particularly with DEC-systems, I have to
admit, I was VERY impressed with the way in which the little EMULEX SCSI board
outperformed their own ESDI board while cutting our rotating memory system cost
by nearly half. Everybody talked about the 15Mbit transfer rate on the ESDI
card, yet the SCSI, which, under exhaustive testing averaged about 250 KBps
under MSCP outperformed the ESDI hands down. This suggests a really decent and
feature-rich implementation of the SCSI extended command set, allowing for
command queueing, operation overlaps, disconnect/reconnect, etc.

Dick

----- Original Message -----
From: "Chuck McManis" <cmcmanis_at_mcmanis.com>
To: <classiccmp_at_classiccmp.org>
Sent: Sunday, July 08, 2001 11:04 PM
Subject: Re: Ended auction for qbus SCSI


> At 12:44 AM 7/9/01 -0400, Chad wrote:
> >Wow, I knew they were pricey, but I didn't know they were that
> >expensive! I guess I should have asked about it. If I knew it was two
> >cards in one, maybe I would have bid. I would very much like to put a
> >scsi card into my MicroVax 3400.
> >
> >You say, "two scsi controllers on one card", so would that be the same
> >as dual channel?
>
> Yes, Emulex didn't come out with a controller that could do both Disk
> devices (MSCP) and tape devices (TMSCP) on the same SCSI string as far as I
> can tell. Instead they took the UC07 (which will control either disk or
> tape but not both) and doubled it up. This particular version is the
> UC08-III which has the S-box handles, the UC08 (no suffix) just has dual 50
> pin headers). They also sold a UC07 that was a dual wide card and a UC07
> that was the same board as the UC08 only it was half populated.
>
> This was different that CMD (the other most popular SCSI controller for
> Qbus) with their CQD series which could, on some models, do both tape and
> scsi on the same string. In my order of desirability they go
> CQD-xxx (both disk and tape on one string
> UC07/8
> SQ739 (Dilog's version of a card similar to the CMD card)
> VIK-QTD (Viking controller, a bit slower in my experience, harder to
> configure)
>
> There were others, Trimarchi, Standard MicroSystems, several rebadged
> Vikings, and CMS.
> But since DEC was pushing DSSI they really discouraged using SCSI
> controllers. :-)
>
> --Chuck
>
>
>
>
Received on Mon Jul 09 2001 - 00:20:41 BST