12 Dec
1999
12 Dec
'99
1:15 a.m.
This weekend I saved most of a uVAX II from the scrapper. It is a
configuration I didn't recognize with two BA23's. One "normal BA23 and then
a Q22 jumper into a second BA23. The rack "sleeves" were connected across
the back with a hinged door that held all the cabinet hardware. Pretty neat.
Anyway, in what was a total shock, the thing has a "Transitional Technology
Inc, QTD-1" Q-bus SCSI controller! If this thing works I'll be in heaven
since I've yet to get a working SCSI disk controller for my Vaxen.
This looks kind of like a Viking controller, except it has several key (and
hopefully really good) differences:
1) It has a 10 pin header that looks like the DEC standard DLV-11 type serial
port (rather than the viking "in the scsi cable" port.)
2) It has an NCR53C90 SCSI interface, and 18 nat'l semi 75176BN chips wired up
to the 50 pin connector. (I'm hoping these are differential drivers for
FAST
SCSI II drives)
3) Then it has a Motorola M68901 a covered 40 pin chip (probably the
processor)
and one RCA 6264 ram chip and a 27C256 EPROM with the "1.7a" firmware
in it.
Has anyone used one of these? Do you have docs on it? Would you be willing
to FAX me the setup information? (I've got a 9GB SCSI drive just waiting
for this type of information :-)
Other interesting bits was the KA630 + 2 8MB memory boards (M7609), a
DHV-11, an M8020 SLU, and an SDI controller (two board set.) The BA23's
suffered some damage when they were ripped from the rack (which I didn't
save) but there seems to be a salvagable TK50 in one of them and a Q/Q
backplane. (The second BA23 was all Q/Q slots!
--Chuck
12 Dec
12 Dec
1:41 p.m.
Chuck McManis <cmcmanis(a)mcmanis.com> wrote:
2) It has an NCR53C90 SCSI interface, and 18 nat'l
semi 75176BN chips
wired up to the 50 pin connector. (I'm hoping these are differential
drivers for FAST SCSI II drives)
There's good news and bad news. The good news is that yes, those definitely
are differential transceivers.
The bad news is that FAST SCSI 2 is *NOT* differential. It's single
ended. 99.9% of the drives you're likely to encounter are single-ended.
Differential and single-ended will not mix [1].
It sounds like this controller will ONLY work with differential drives,
unless they provided some sort of jumper arrangement to bypass the
differential transceivers.
There exist single-ended to differential converters, but they're very
expensive.
Good luck!
Eric
[1] The new-fangled "Low Voltage Differential" (LVD) is different than the
traditional SCSI differential. They cleverly designed most (all?) LVD
drives so that they will work on either LVD or single-ended busses. But
LVD drives will NOT operate on traditional differential SCSI.
2:44 p.m.
At 19:41 12-12-1999 -0000, Eric Smith wrote:
The bad news is that FAST SCSI 2 is *NOT* differential.
It's single
ended. 99.9% of the drives you're likely to encounter are single-ended.
Differential and single-ended will not mix [1].
While it's true that the majority of the drives encountered are
single-ended, the statement "FAST SCSI-2 is not differential" is not
accurate. I know it to be inaccurate for two reasons.
1). Differential is merely the signaling interface. SCSI, as a protocol,
couldn't care less whether the I/F is SE or Diff. In fact, FAST rates will
work better on diff because of the low susceptibility to noise.
2). I've come across a wide variety of Fast SCSI-2 drives, both here in my
lab and at the used computer place I frequent, that are indeed
differential. Most of them were Seagates, and you can tell they're diffs by
(a), the termination arrangement, and (b), the fact that they have a 'D' at
the end of their model number.
Example: ST43400ND. 5.25" full-height SCSI-2 Fast HD, Elite series, 2.9
gigs formatted capacity.
As one final example, I once converted a Fujitsu 3.5" Fast SCSI-2 HD from
diff to SE simply be swapping in the SE-interface logic board from an
identical drive with bad media.
You are, however, absolutely right in the statement that diff and SE
cannot be mixed on the same bus. The only exception is using an SE-to-Diff
adapter for the mismatched device.
There exist single-ended to differential converters,
but they're very
expensive.
Unless you can find them surplus, in which case they're often $10 or less.
;-)
[1] The new-fangled "Low Voltage
Differential" (LVD) is different than the
traditional SCSI differential. They cleverly designed most (all?) LVD
drives so that they will work on either LVD or single-ended busses. But
LVD drives will NOT operate on traditional differential SCSI.
Yes and no. When an LVD drive is installed on an SE bus, it merely
switches to SE mode. The advantages of LVD are lost.
Clarification from the Great(?) Northwest! ;-)
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner and head honcho, Blue Feather Technologies
http://www.bluefeathertech.com // E-mail: kyrrin(a)bluefeathertech.com
Amateur Radio: WD6EOS since Dec. '77
"Our science can only describe an object, event, or living thing in our
own human terms. It cannot, in any way, define any of them..."
4:08 p.m.
At 07:41 PM 12/12/99 +0000, Eric Smith wrote:
Chuck McManis <cmcmanis(a)mcmanis.com> wrote:
Well, I "liberated" a couple of 2+ GB drives (Seagates) from a Sun 490 disk
tray that suggest they are differential SCSI. I could live with 4GB :-).
Its intereface termination resistors are plug in sips. I wonder if they
used the trick where you replace the four rows of sips with a single DIP
terminator to switch it to an SE bus. TransTech still has a web site but so
far no word from their Support email.
Another interesting bit is that it is a QDT so presumably it is disk and
tape, but I don't think I've ever seen a differential tape drive. Perhaps
they assume the tape drive has the converter on it.
2) It has an NCR53C90 SCSI interface, and 18
nat'l semi 75176BN chips
wired up to the 50 pin connector. (I'm hoping these are differential
drivers for FAST SCSI II drives)
There's good news and bad news. The good news is that yes, those definitely
are differential transceivers.
The bad news is that FAST SCSI 2 is *NOT* differential. It's single
ended. 99.9% of the drives you're likely to encounter are single-ended.
Differential and single-ended will not mix [1]. It sounds like this controller will ONLY work with
differential drives,
unless they provided some sort of jumper arrangement to bypass the
differential transceivers.
To be determined.
There exist single-ended to differential converters,
but they're very
expensive.
Actually I recall that Disk Drive Depot sells them fairly cheaply. (less
than $20 as I recall)
--Chuck
4:39 p.m.
At 07:41 PM 12/12/99 +0000, Eric Smith wrote:
Also, for the difinitive answer on whether your drives are differential or not,
I'd suggest going to www.seagate.com and looking them up. And re: disk drive
depot, their parent corporation does business on the web as www.corpsys.com.
--
Jim Strickland
jim(a)DIESPAMMERSCUMcalico.litterbox.com
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Chuck McManis <cmcmanis(a)mcmanis.com> wrote:
Well, I "liberated" a couple of 2+ GB drives (Seagates) from a Sun 490 disk
tray that suggest they are differential SCSI. I could live with 4GB :-).
Its intereface termination resistors are plug in sips. I wonder if they
used the trick where you replace the four rows of sips with a single DIP
terminator to switch it to an SE bus. TransTech still has a web site but so
far no word from their Support email.
Another interesting bit is that it is a QDT so presumably it is disk and
tape, but I don't think I've ever seen a differential tape drive. Perhaps
they assume the tape drive has the converter on it.
2) It has an NCR53C90 SCSI interface, and 18
nat'l semi 75176BN chips
wired up to the 50 pin connector. (I'm hoping these are differential
drivers for FAST SCSI II drives)
There's good news and bad news. The good news is that yes, those definitely
are differential transceivers.
The bad news is that FAST SCSI 2 is *NOT* differential. It's single
ended. 99.9% of the drives you're likely to encounter are single-ended.
Differential and single-ended will not mix [1]. It sounds like this controller will ONLY work with
differential drives,
unless they provided some sort of jumper arrangement to bypass the
differential transceivers.
To be determined.
There exist single-ended to differential
converters, but they're very
expensive.
Actually I recall that Disk Drive Depot sells them fairly cheaply. (less
than $20 as I recall)
--Chuck
5:38 p.m.
>Chuck McManis <cmcmanis(a)mcmanis.com> wrote:
Another interesting bit is that it is a QDT so
presumably it is disk and
tape, but I don't think I've ever seen a differential tape drive. Perhaps
they assume the tape drive has the converter on it.
Diff tape drives are all we use at work.
There exist
single-ended to differential converters, but they're very
expensive.
Actually I recall that Disk Drive Depot sells them fairly cheaply. (less
than $20 as I recall)
9161
days inactive
9161
days old
5 comments
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participants (5)
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cmcmanis＠mcmanis.com -
eric＠brouhaha.com -
healyzh＠aracnet.com -
jim＠calico.litterbox.com -
kyrrin＠bluefeathertech.com