DECtapes have 5x redundant tracks. If you could find an 8-track head that
had the same track pitch, and maybe track width, you could read the tape
but lose redundancy on the Mark and Timing tracks. That probably would not
work with a marginal DECtape.
On Mon, Feb 7, 2022 at 3:33 PM Wayne S <wayne.sudol at hotmail.com> wrote:
> I?ve often wondered if the tape heads from consumer tape devices such as
> cassette or 4-8 track tape players could be used or be made to be used as
> replacements. Anybody ever try that?
>
> Sent from my iPhone
>
> > On Feb 7, 2022, at 11:51, Michael Thompson via cctech <
> cctech at classiccmp.org> wrote:
> >
> > ?
> >>
> >>
> >> From: Gary Oliver <go at aerodesic.com>
> >> Subject: DECTape head problem
> >>
> >> In debugging my DECtape interface lashup, I found that one of my head
> >> has two open windings.? Specifically, one channel has an open 'ground'
> >> with the other two lines apparently the full winding of the channel.?
> >> The second channel failing has no continuity between any of the three
> >> lines.? I have tested the other head and it has all the requisite
> >> continuity so I'm hoping I can at least get a single spindle running.
> >>
> >> Has any ever attempted repair of one of these?
> >>
> >> -Gary
> >>
> >
> > At the Rhode Island Computer Museum we found several DECtape heads on
> TU55
> > and TU56 drives with open connections. A volunteer got one head X-Rayed
> so
> > we could see the solder joints between the tiny wires for the head coils,
> > and the larger twinax wires that go to the relay board. We couldn't see
> any
> > damage to the wires or solder joints.
> >
> > We tried heating the potting material to soften it, and digging it out to
> > get to the solder joints. While digging at the potting material you can't
> > see the tiny wires, so they will likely get damaged.
> >
> > We considered using a solvent to remove the potting material, but thought
> > that it would eat the enamel off the head coil wires and damage them
> beyond
> > repair.
> >
> > So far we haven't found a way to repair the heads.
> >
> > Michael Thompson
>
--
Michael Thompson
>
> From: Gary Oliver <go at aerodesic.com>
> Subject: DECTape head problem
>
> In debugging my DECtape interface lashup, I found that one of my head
> has two open windings.? Specifically, one channel has an open 'ground'
> with the other two lines apparently the full winding of the channel.?
> The second channel failing has no continuity between any of the three
> lines.? I have tested the other head and it has all the requisite
> continuity so I'm hoping I can at least get a single spindle running.
>
> Has any ever attempted repair of one of these?
>
> -Gary
>
At the Rhode Island Computer Museum we found several DECtape heads on TU55
and TU56 drives with open connections. A volunteer got one head X-Rayed so
we could see the solder joints between the tiny wires for the head coils,
and the larger twinax wires that go to the relay board. We couldn't see any
damage to the wires or solder joints.
We tried heating the potting material to soften it, and digging it out to
get to the solder joints. While digging at the potting material you can't
see the tiny wires, so they will likely get damaged.
We considered using a solvent to remove the potting material, but thought
that it would eat the enamel off the head coil wires and damage them beyond
repair.
So far we haven't found a way to repair the heads.
Michael Thompson
I'm going through? a few of my ESDI? and MFM hard drives? and ran across?2 Maxtor? XT 2190 drives with? all of the Drive Id's (1-4) tie together with 1 long
jumper and the drives have the write protect jumper is installed.? Not sure what theywould have been used for ??? Both are the same.
Jerry
There is a nice looking IBM 129 keypunch on Ebay for what I think is a very
reasonable "buy it now" price of US$1799:
https://www.ebay.com/itm/333898748391
Shipping to Australia would be horrendous otherwise I would have bought it.
Best regards
Tom Hunter
I'm putting stuff together here and it's time to begin working on the
8/E. Looks like a pretty generic system but it has two odd boards.
Pair of g227 memory boards, 4 board CPU+Console board, serial board,
nothing too special.
But two odd Omnibus cards: One is a memory board, half populated, my
guess is it's enough memory to bring the computer to 32kw. The other is
an mets 303-0115-001. Bunch of 7400 series logic chips, nothing too
special.
Any idea what it might have been? Timeshare option? Something else? Not
a peripheral controller from what I can see.
C
On Thu, Feb 3, 2022 at 1:08 PM <cctalk-request at classiccmp.org> wrote:
>
> Send cctalk mailing list submissions to
> cctalk at classiccmp.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://www.classiccmp.org/mailman/listinfo/cctalk
> or, via email, send a message with subject or body 'help' to
> cctalk-request at classiccmp.org
>
> You can reach the person managing the list at
> cctalk-owner at classiccmp.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of cctalk digest..."
>
>
> Today's Topics:
>
> 1. (John Ames)
> 2. Re: (Paul Koning)
> 3. Re: (Jon Elson)
> 4. Re: KMC11/DMC11 folllow up (Dave Mitton)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 2 Feb 2022 10:20:25 -0800
> From: John Ames <commodorejohn at gmail.com>
> To: cclist at sydex.com
> Cc: cctalk at classiccmp.org
> Message-ID:
> <CABCBCvP8SX_1rB3FXVxZuXx1SUFTfiJBTqePd_SZiNeReX7PEw at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> > Back in the bad old days of the 5160 PC, some DTC controllers allowed for partitioning a drive (using witch settings)
> I think "witch settings" is my new preferred term for this. They're
> certainly mysterious and arcane enough.
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 2 Feb 2022 13:30:33 -0500
> From: Paul Koning <paulkoning at comcast.net>
> To: John Ames <commodorejohn at gmail.com>, "cctalk at classiccmp.org"
> <cctalk at classiccmp.org>
> Subject: Re:
> Message-ID: <B8F20F9C-A329-4CED-9A00-036EAA8F4D1A at comcast.net>
> Content-Type: text/plain; charset=us-ascii
>
>
>
> > On Feb 2, 2022, at 1:20 PM, John Ames via cctalk <cctalk at classiccmp.org> wrote:
> >
> >> Back in the bad old days of the 5160 PC, some DTC controllers allowed for partitioning a drive (using witch settings)
> > I think "witch settings" is my new preferred term for this. They're
> > certainly mysterious and arcane enough.
>
> Nice. It would be a good term to apply to VMS SYSGEN parameters that are documented as having units "microfortnights".
>
> paul
>
>
>
> ------------------------------
>
> Message: 3
> Date: Wed, 2 Feb 2022 16:49:42 -0600
> From: Jon Elson <elson at pico-systems.com>
> To: Paul Koning via cctalk <cctalk at classiccmp.org>
> Subject: Re:
> Message-ID: <b0989916-7493-481d-7c45-a696ce5ecc31 at pico-systems.com>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> On 2/2/22 12:30, Paul Koning via cctalk wrote:
> >
> >>
> > Nice. It would be a good term to apply to VMS SYSGEN parameters that are documented as having units "microfortnights".
> >
> A footnote in the system config guide noted that ufortnights
> would be approximated at one second.
>
> Jon
>
>
>
> ------------------------------
>
> Message: 4
> Date: Wed, 2 Feb 2022 14:31:27 -0500
> From: Dave Mitton <dave at mitton.com>
> To: "cctech at classiccmp.org" <cctech at classiccmp.org>
> Subject: Re: KMC11/DMC11 folllow up
> Message-ID: <20220202193130.24EDC4E775 at mx2.ezwind.net>
> Content-Type: text/plain; charset="utf-8"
>
> Date: Tue, 1 Feb 2022 18:46:46 -0500
> From: Bob Smith <bobsmithofd at gmail.com>
> Subject: Re: KMC11/DMC11 folllow up
> Message-ID:
> I?ve been watching this thread go by, and never finding time to contribute?.
>
> I started in Aug 1977 and finished the CommIOP products from Bob and Harvey. Clarise was no longer involved.
> It was basically done, I just did the QA on them and released it. I did find some bugs in the debugger we provided.
>
> I basically did KMC software support, on and off, going forward. When the KMC-B came out (I think Remi did that)
> I rev?ed the tools. I also did a KMC Tools package for VMS. I tossed into that package a VMS line printer driver, I wrote as an example and POC, that ran multiples LP11s at significantly better speed. We ran that in our lab. The MIT LCS lab loved that.
>
> My memory is weak on things like the ?DMX? and other things that CSS did. The Lab Products group built some successful data collection products around the KMC.
>
> Attempts in the Comms HW group to do an updated UNIBUS DH never got off the ground. We (NAC) did pitch the idea of using the CommIOP-DZ to VMS, as a way to off-load character terminal loads, and they would have nothing to do with it. For whatever reasons, they did not like the idea of smart devices.
>
> That led to the attempt to build a ?universal? terminal concentrator based on an 11 networked into the system. That project was complicated by what it tried to integrate, and took too long to build. It was overtaken by the simpler LAT based products that DEC went forward with.
>
> George Conant, Bob Rosenbaum, and Pete Nesbeda left the company and founded Xyplex that fielded successful products in this space.
>
> I could go on, but ? I do have copies of the KMC Tools doc and maybe the CommIOPs, but no KMC hw docs.
> Dave.
>
> Sent from Mail for Windows
>
>
Hey Dave! I did not mention you because I was not sure you wanted to
recall those days! you are correct it was Remi Lisee doing the design,
I did the first line units, and then they were redone a few years
later. Glad you piped in!! Hope you are doing great! All of you guys
were brilliant, except Harvey, he was a royal pain, said with lots of
laughs we both got tired or burning roms!!
bob smith
> Back in the bad old days of the 5160 PC, some DTC controllers allowed for partitioning a drive (using witch settings)
I think "witch settings" is my new preferred term for this. They're
certainly mysterious and arcane enough.
Date: Tue, 1 Feb 2022 18:46:46 -0500
From: Bob Smith <bobsmithofd at gmail.com>
Subject: Re: KMC11/DMC11 folllow up
Message-ID:
<CAHtNYbXBRwrOQm2cH+T+CDn5nq3sZN+PQRa9fEMVhqQ=pAMDSw at mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Yes! thank you! Nice, smart, and did good work despite the magateer, I
mean marketing dweeb.
I lost track of Harvey, Bob wen ont to start a company over in west
concord, can't recall the name, used some of his gear for projects in
the mid 80s.
I was designing a comms system in late 80s and heard Len Bosak had
started a company, had a couple of meetings with him, and went with hs
gear. Man those were fun post DEC projexcts.
bob smith (PDP8 engineering, DecComm (Stockebrand, VInce et al), small
systems, then of toe LCG for 2080...
On Tue, Feb 1, 2022 at 2:43 PM John Forecast <john at forecast.name> wrote:
>
> On Feb 1, 2022, at 8:20 AM, Bob Smith via cctalk <cctalk at classiccmp.org> wrote:
> >
> > KMC11 - Paul K cited the docs. It was a bit different from DMC CPU board
> > in both cycle time and in the use of ram versus prom.
> > Both boards/products used the 4bit Alu but I don't call that bit
> > slice, as the 2901 is more of a bit slice.
> > KMC and DMC are Harvard architecture based devices, as is the 11/60 CPU.
> > DMC and KMC benefited from the microcode work of Harvey Schlesinger,
> > Bob Rosenbaum, Richie Larry, and I think Clarise joined the team in
> > 77. Can't recall her last name.
>
> Patton? Harvey, Bob and Clarise joined the DECnet-RSX development team sometime in 77/78.
>
> John.
>
> > DMC had (when I left the project and it had been shipping for a year
> > or two) a 300NS cycle time, while the KMC had a 240NS cycle time
> > thanks to the instruction register I had suggested to remi as we were
> > thinking of a RAM based device because PROMS were a royal pain with 2
> > and 3 code changes a day. This change allowed the machine to begin to
> > access the next instruction as one was executing - there are no
> > interrupts in either board.
> > bob
>
I?ve been watching this thread go by, and never finding time to contribute?.
I started in Aug 1977 and finished the CommIOP products from Bob and Harvey. Clarise was no longer involved.
It was basically done, I just did the QA on them and released it. I did find some bugs in the debugger we provided.
I basically did KMC software support, on and off, going forward. When the KMC-B came out (I think Remi did that)
I rev?ed the tools. I also did a KMC Tools package for VMS. I tossed into that package a VMS line printer driver, I wrote as an example and POC, that ran multiples LP11s at significantly better speed. We ran that in our lab. The MIT LCS lab loved that.
My memory is weak on things like the ?DMX? and other things that CSS did. The Lab Products group built some successful data collection products around the KMC.
Attempts in the Comms HW group to do an updated UNIBUS DH never got off the ground. We (NAC) did pitch the idea of using the CommIOP-DZ to VMS, as a way to off-load character terminal loads, and they would have nothing to do with it. For whatever reasons, they did not like the idea of smart devices.
That led to the attempt to build a ?universal? terminal concentrator based on an 11 networked into the system. That project was complicated by what it tried to integrate, and took too long to build. It was overtaken by the simpler LAT based products that DEC went forward with.
George Conant, Bob Rosenbaum, and Pete Nesbeda left the company and founded Xyplex that fielded successful products in this space.
I could go on, but ? I do have copies of the KMC Tools doc and maybe the CommIOPs, but no KMC hw docs.
Dave.
Sent from Mail for Windows
There is a discussion of the origin of the term "partition" in storage
devices such as HDDs at:
https://en.wikipedia.org/wiki/Talk:Disk_partitioning#Where_did_the_term_%22p
artition%22_originate?
It seems clear it was used in memory well before HDDs but when it got
started there is unclear.
* IBM PC DOS v2 was an early user in 1983 with FDISK and its first PC
support of HDDs
* UNIX, Apple OS's and IBM mainframe all seem to come later.
Partitioning as a "slice" probably predates IBM PC DOS v2
Would appreciate some recollections about DEC usage, other minicomputers and
the BUNCH.
You can either post directly to Wikipedia or let me know; links to
references would greatly be appreciated
Tom
