DEC VS2000 and SCSI, was Re: DEC RD54 from Maxtor

From: Ethan Dicks <erd_6502_at_yahoo.com>
Date: Wed Mar 5 13:37:01 2003

--- Steve Jones <classiccmp_at_crash.com> wrote:
> uVAX FAQ), which means development and planning may have started
> as early as 1983 - I'm just guessing here.
>
> In the early 80s large (> 20MB) ST-506 hard drives were still
> hugely expensive beasts. If you did find a native SCSI device, I
> imagine the costs would be much higher for the extra interface logic
> on the drive. Without native SCSI on the device, you needed a
> translator like the Adaptec ACB-4000 (SCSI/ST-506) or Emulex MT-02
> (SCSI/QIC-02).

I bought my first microcomputer hard drive in 1987. It was an ST-225
that I attached to an Amiga 1000 over an 8-bit ISA bus adapter called
"The Wedge" - the drive (with WX-1 ISA controller) was around $350.
ISTR that bare ST-225 drives were right around $300-$325. Between
the PC drive/controller and the Amiga adapter plus an external (used)
enclosure, I put 20MB on my Amiga for around $500 total. At the same
time, a C Ltd SCSI interface plus external 20MB SCSI drive (probably
an ST-225 + ACB-4000, not certain) was $1,000.

I do not think that the uVAX-2000 ever shipped with anything as small
as 20MB. All the ones I've seen had either RD53s (71MB) or RD54s (154MB).
DEC, of course, charged a huge amount per megabyte for their drives,
so my comparison of the costs of an Amiga drive have to be taken into
that context.

I do not know why DEC decided to go with SCSI for the uVAX-2000 tape.
That they went with ST506/ST412 disk drives is no surprise - it was
what they had been working with since the uVAX-I/RQDX1, Rainbow and
DECmate - if you wanted 5.25" storage, your choices in 1983-1985
were limited to ST506/ST412 and ESDI (ESDI cost even more, but it
was higher performance). Even the Mac drives weren't embedded SCSI
until later, and then, 20MB was generous (ST-225N in 5.25" width,
and a number of 3.5" models from various vendors).

I'm surprised that DEC didn't make a wierd buffered cable/interface
for the raw TK50 interface. Given how much hardware is on the
board in a TK50Z, I suppose there wasn't room. The SCSI circuit
on the uVAX2000 motherboard takes up only a few square inches (the
5380 chip itself, a minimal amount of select logic, plus the connector
at the back).

So... just a couple of data points on drive costs of the era when the
uVAX-2000 was surfacing. I saw my first one at a DECUS in either Anaheim
or Cincinnati around 1987 or 1988 (not that they were new then, but they
were new to me - everywhere I'd worked, it was all Unibus and Qbus VAXen).

-ethan
Received on Wed Mar 05 2003 - 13:37:01 GMT