Suggestions for "the fastest" Q22/SCSI-interface?
n...@eta.chalmers.se
I'd like your "educated opinions" upon which SCSI-adapter that would
be "the fastest" for the Q-22 bus... (if that can be achieved without
starting a "religious" fight...)
I've seen some indications that CMD's CQD 440 would be a candidate,
but on "bitsavers", I can only find a manual for CQD 420. What would
be the difference upon these two?
Reason for my questions: I've been given (privately) a Compaq HSZ-80
storage array, and it would be quite amusing to have a PDP (11/93)
entirely hooked up on this (besides an old alpha-station etc).
This storage is connecting using "Ultra SCSI-II" on
"Differential" (HVD) signalling, so diff (HVD) is sort of a
requirement of mine for the Q-bus interface I could spend some hobby
money upon getting this hardware, but as all hobby budgets, there is a
limit...
But, the "greedy" part of mine wants to find out which interface would
be "the fastest", just for the h... of it! I'm primarilly running RSX
operating system, but others would be a fun alternative. With the
storage, I could have plenty of disc partitions for different OS:es!
Best regards, Göran Å
Tim Shoppa
wrote:
I did (and published) some benchmarks of SCSI MSCP-emulating
controllers probably a decade ago. And indeed the CMD CQD 440 was the
winner. But they all beat the pants off a RQDX3!
Here are the peak data rates measured for read and write 64
blocks-at-a-time:
Read Write
---------- ----------
Andromeda SCDC 2.298 MB/s 1.131 MB/s
CMD CQD440 2.397 MB/s 1.525 MB/s
CMD CQD220 1.418 MB/s 0.882 MB/s
CMD CQD220A 2.088 MB/s 1.409 MB/s
DEC RQZX1 1.379 MB/s 1.097 MB/s
Viking QDT 0.846 MB/s 0.704 MB/s
DEC RQDX3 0.164 MB/s 0.161 MB/s
The benchmarks were done under RT11FB 5.7 doing 1, 2, 4, 8, 16,
32, and 64 block-at-a-time READW's and WRITW's to 16384-block
data files. A KDJ11B (PDP-11/73) CPU with 2 Megabytes of Clearpoint
non-PMI memory was used for the bencharmks. With the SCSI
controllers a Barracuda 7200 RPM ST15230N drive was used; with
the RQDX3 a RD52 drive was used.
Tim.
Tim Shoppa
> different CMD controllers are?
Speaking from deep memory:
the 2's are dual-height boards
the 4's are quad-height boards
If it ends with a 3, it's got the bulkheads for the Skunk-box (BA213)
style cabinet
I think there was a suffix to denote whether it spoke single-ended or
differential SCSI.
I think 4's had both single-ended and differential SCSI in some (all?)
cases... I think that's why they had two fifty-pin connectors, and
there were jumpers to select which connector was used. Geeze, it's
been too many years, like the Fuji Eagle jumper configs for sector
size that I used to have in my head too! Man, I could tear down five
broken Fuji Eagles and build back up 4 working Fuji Eagles in a
heartbeat at one time...
Jerome H. Fine
>I did (and published) some benchmarks of SCSI MSCP-emulating
>controllers probably a decade ago. And indeed the CMD CQD 440 was the
>winner. But they all beat the pants off a RQDX3!
>
>Here are the peak data rates measured for read and write 64
>blocks-at-a-time:
>
>
> Read Write
> ---------- ----------
>Andromeda SCDC 2.298 MB/s 1.131 MB/s
>CMD CQD440 2.397 MB/s 1.525 MB/s
>CMD CQD220 1.418 MB/s 0.882 MB/s
>CMD CQD220A 2.088 MB/s 1.409 MB/s
>DEC RQZX1 1.379 MB/s 1.097 MB/s
>Viking QDT 0.846 MB/s 0.704 MB/s
>DEC RQDX3 0.164 MB/s 0.161 MB/s
>
>The benchmarks were done under RT11FB 5.7 doing 1, 2, 4, 8, 16,
>32, and 64 block-at-a-time READW's and WRITW's to 16384-block
>data files. A KDJ11B (PDP-11/73) CPU with 2 Megabytes of Clearpoint
>non-PMI memory was used for the bencharmks. With the SCSI
>controllers a Barracuda 7200 RPM ST15230N drive was used; with
>the RQDX3 a RD52 drive was used.
>
Jerome Fine replies:
I would VERY much appreciate an opportunity to run the identical
benchmark and compare it with the ESDI controller that I have,
a Sigma RQD11-EC. Any possibility of obtaining the code?
Sincerely yours,
Jerome Fine