I've always thought the physical tape wound on a DECtape spool was a
fairly conventional 'sandwich' of mylar/oxide/mylar, but a recent 'test'
makes me think there is something else involved.
I have a number of tapes I'm cleaning (removing dust, etc.)? to make
ready to read on a restored (apparently) Astrotype dual DECtape drive
and I was 'dressing' the leaders of the tape (removing ragged bits from
old use.)? After trimming a wee bit from several tapes (.5 to 1 inch) I
did a test.? Taking the bits of tape, I exposed them to various
concentrations of isopropanol/water (from about 25% to 99% iso) and
found than in all cases, some of the data side of the tape came off on
the wipe.? The remaining tape fragment appears intact - the brown oxide
was still there but both sides were now the same color, rather than the
data side being darker (as were all my tapes before the test.)
Was there some kind of 'lubricating' coat on the data side?? It makes
sense, but none of my DEC documents or Googling has any mention of
lubrication, other than the "...hydro- dynamic lubrication, relying on
the viscosity of air to entrain it with the tape and provide the
flotation medium." found in an "ELECTROMECHANICAL COMPONENTS & SYSTEMS
DESIGN" from November,? 1964.
All of my tapes, including DECtape brand, Scotch brand and even a couple
of old "Microtape" brand from DEC (before 'dectape' name change) have
this feature, so this doesn't appear to be something that appeared
recently (as in late in DECtape production or due to old-age in the tapes.)
If someone has some detail information on the tape construction, I'd am
curious to see it.
Thanks,
Hello,
I had picked up these machines fresh out of high school. I actually worked
a deal with the buyer to make payments out of my paycheck for a few weeks
till they were paid in full. i have not had the time to focus and get them
running.
one machine i have had up to the cpu monitor, no internal disk drive.
the second machine has some corrosion on the front panel board, where the
battery leaked. it iminimal, and the bad battery is removed.
open to offers.
located in US Florida
Looking to sell off excess stuff, i want to focus on my pdp11's and
mainframes.
Going through an old junk pile, I came across a couple of core boards:
Micro Memory, Inc.
PN 90360 8K*8 (MM-6800)? Date code 7725
I have two boards (s/n 202 and 203) so likely purchased in pairs.
Anyone have any information on these?? They have 86 pin connectors so
not S-100 though connector is about the same size.
For years, these have sit on a shelf on my 'round tuit' list of bringing
them up in one of my old S-100 boxes, so I've been cruising along
thinking these were 100 pin connectors.? I got them out today so I could
find the manual (I have used the MMI s-100 8kx8 boards in an old company
project back in 1977 and those were about the same size and form.)? The
core board is a daughter board on top of the board with the bus
connector and is likely the same module from the S-100 board.? I'm
guessing the 86 pin bus is a Motorola Exorciser bus - so I can probable
figure it out from there, but I would like to find a manual.
I think my company had an Exorciser development system in the late 70s.?
These were obtained from a dumpster dive.? Pity I didn't get the rest of
the box, if so.
As usual, google wasn't extremely helpful with old pedestrian hardware
searches.
-Gary
> From: Gary Oliver
> I've always thought the physical tape wound on a DECtape spool was a
> fairly conventional 'sandwich' of mylar/oxide/mylar ...
> Was there some kind of 'lubricating' coat on the data side? It makes
> sense, but none of my DEC documents or Googling has any mention of
> lubrication ...
> If someone has some detail information on the tape construction, I'd am
> curious to see it.
Dunno if you know of this:
http://www.bitsavers.org/pdf/dec/dectape/3M_DECtape_Spec_Nov66.pdf
but it doesn't mention any lubrication, just a "Protective Overlay" layer,
over the "Coating" (which I assume is the oxide). I'm a bit surprised that
"some of the data side of the tape came off on the wipe", though, unless the
"various concentrations of isopropanol/water" dissolved the Protective
Overlay.
Noel
Hi,
I have a mystery S-100 computer that I'm would like to sell, from the
estate of the late Ken Gielow (author of Z80DIS, a great Z80 disassembler).
The proceeds will be donated to a non-tax-deductible magic group Ken was a
long-time member of.
The computer is located in Cupertino, CA (aka "the heart of Silicon
Valley", in the S.F. Bay Area). (If reopened, you can combine a pickup
with a visit to the Computer History Museum in nearby Mountain View, CA! :)
This would likely be quite expensive to ship. I'd guess 30+ pounds.
Photos and some info at:
www.sieler.com/ken_photos
Some of the hardware (also listed on the above page):
ThinkerToys buss
unknown semi-transparent front panel
spare/uninstalled Ithaca Intersystems DPS-1 front panel
10 various boards inside
metal case (heavy)
There may be manuals on some of the boards and/or the Ithaca, but I'm not
sure yet. (They would be included, if they exist.)
I wanted to take photos of each board, but having been seated for about 40
years, they don't come out if I tug gently. None have integrated board
lifters, unfortunately
(I tried a boroscope, but could not get useful photos.)
Based on the labels on some EPROMS, there's a chance that it's a homebrew
TRS-80 clone, with both Level II BASIC and CBASIC, and may have Morrow
DISCUS software on it.
We're looking for an offer on either:
- the Ithaca Intersystems front panel;
- the computer with all the boards
or both.
Suggestions welcome, thanks!
> From: Gary Oliver
> Paul - thanks for the bitsavers reference.
Ahem!
In any case, it's Al who really deserves the credit, for finding that document, and
putting it up.
Noel
> From: Gavin Scott
> I think if I had a whole lot of old faded greenbar etc. ... Someone may
> even have done this already
See:
https://walden-family.com/impcode/imp-code.pdf
Someone's already done the specialist OCR to deal with faded program listings.
Noel
I am trying to locate documentation on the PDP-8 clone built by Canadian company Consolidated Computer Inc (Mers Kutt) in the mid 1970's.
An example exists in the UK and will be restored when more data than just the system can be found.
Rod Smallwood - digital equipment corporation 1975-1985
Would someone please suggest a replacement for the Compaq Portable's
brightness knob? This was missing on mine when I got it.
--
David Griffith
dave at 661.org
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
So now that my pdp8/L is up and running (it now has a serial port and
runs FOCAL69 quite well) I'm thinking about the next step, which is of
course more memory.
This requires a BA08 or BM8/L or something expansion box but to be
honest I have enough spare flip chips and such from the wrecked 8/I to
build about 3 core memory systems. So given that the schematics for the
BA08 are online, they look pretty darn simple, I have the parts, and I
have the parts does anyone know if it's possible to get a flip chip
backplane to work on and wire up to emulate a BA08?
It looks like they just used the data break interface lines to hook up
to the processor. Everything's there, Memory address bus, memory data
bus, and the various signals for jumps and the like that could allow one
to decode and implement the extra instructions needed.
Hm. Might just be easier to build it with an FPGA or something as it's
mostly linking up simple gates and the whole core memory section could
be removed by a 4k*12 memory array. Anyone ever done this?
C
> This:
> https://www.ebay.com/itm/275084268137
> ...
> Anyway I fully expect it to go ... for a _lot_ more than the opening price.
Much to my surprise, it didn't sell at all (although a number of other lots,
likely from this machine, did.)
I'm rather puzzled that an -11/70 will sell for north of $10K, while a /780
can't fetch $5K. I can only guess that PDP-11'S are seen as more important in
the collector world (even though the BSD work, which had such a huge impact on
UNIX, which has now - in the form of Linux - taken over the world, was
centered on the VAX).
Noel
https://i.imgur.com/48EfOQG.jpg
That's after sitting parked a couple months. I have a Dysan doing it too. The Dysan had been re-banded with a boiled 3M band and run for years like that with no shedding. I have another Dysan with a green Plastiband in it which is also fine, minimal/no shed. So, I think we may need to re-evaluate if the clear Amazon cheap "plastibands" are perhaps totally incompatible with tape.
I know, I know..."just use the band to get data off." But I want to *run* QICs without having to destroy them constantly.
Thanks,
Jonathan
I think I may need to replace the two output capacitors in some of my H744
regulators. These are screw terminal 6,000uF 10V parts. I have looked on
Mouser, Farnell and Digikey and there don't seem to be any available, and
any that are listed are really rather costly.
Does anyone know where I might find some, preferably from a reputable
supplier. Note that I am in the UK.
If I can't find 10V rated ones, then, generally up to what sort of voltage
rating can I go? Of course, physical size will be a factor, but electrically
can it affect operation of the regulator if the rated voltage is too high?
Thanks
Rob
I am in the process of thinning down my vintage computer holdings, to relieve some of the burden I will leave to my heirs (hopefully not too soon!).
I have a working tiny PDP-11/73 system available for sale. I would much prefer not to have to break it down and pack it for shipping, but I will if the buyer agrees to pay for the packing and shipping costs.
- - - - -
Tiny PDP-11/73 System:
H9281-BA backplane and card cage
KDJ11-A CPU
DLV11-J 4 port SIO
MSV11-LK 256KB/128KW memory
Emulex UC07 SCSI interface
Power-on Reset board from here:
http://www.heeltoe.com/index.php?n=Pcbs.Qbus-por
SCSI-to-SD hard drive emulator with 4 drives available, RT-11 installed
MeanWell RT-125B power supply
4.5 inch AC fan
qty 4 GlitchWorks serial cables
Spare PDP-11/23 CPU saved as a backup:
KDF11-AB CPU
RT-11 Pocket Guide
RT-11 Mini-Reference Manual
- - - - -
I am asking $800.00 for the lot. It cost me about that, probably more to acquire it piece-by-piece and assemble it into a working system.
smp
- - -
Stephen Pereira
Bedford, NH 03110
KB1SXE
Would someone please suggest a suitable screw specification for the Compaq
Portable keyboard? My restoration project was interrupted and I managed
to lose the screws.
--
David Griffith
dave at 661.org
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
I'm looking for a manual I can't find on Bitsavers: a DECnet/10 programming manual. The reason: trying to read PSTHRU.MAC and realizing that I was trying to understand DECnet-10 code while reading the DECnet-20 programming manual. Oops.
paul
I am in the process of thinning down my vintage computer holdings, to relieve some of the burden I will leave to my heirs (hopefully not too soon!).
I have a working tiny PDP-11/73 system available for sale. I would much prefer not to have to break it down and pack it for shipping, but I will if the buyer agrees to pay for the packing and shipping costs.
- - - - -
Tiny PDP-11/73 System:
H9281-BA backplane and card cage
KDJ11-A CPU
DLV11-J 4 port SIO
MSV11-LK 256KB/128KW memory
Emulex UC07 SCSI interface
Power-on Reset board from here:
http://www.heeltoe.com/index.php?n=Pcbs.Qbus-por <http://www.heeltoe.com/index.php?n=Pcbs.Qbus-por>
SCSI-to-SD hard drive emulator with 4 drives available, RT-11 installed
MeanWell RT-125B power supply
4.5 inch AC fan
qty 4 GlitchWorks serial cables
Spare PDP-11/23 CPU saved as a backup:
KDF11-AB CPU
RT-11 Pocket Guide
RT-11 Mini-Reference Manual
- - - - -
I am asking $800.00 for the lot. It cost me about that, probably more to acquire it piece-by-piece and assemble it into a working system.
smp
- - -
Stephen Pereira
Bedford, NH 03110
KB1SXE
I have quite a few Motorola Microsystems Exorciser boards including this
6800 single board computer for which I am lacking any documentation.
I've seen a brochure in Al's collection on Bitsavers but haven't found
any details that might discuss jumper settings or even better,
a schematic.
Wondering if anyone would have a user manual or other detailed docs for
this board?
M68MM01A2 -- has 6800 CPU, 6875 1.0 MHz clock generator, 6850 ACIA and
MC14411 baud rate clock, (4) EPROM/ROM sockets and (2) 6821 PIA sockets
with the 86-pin Exorciser edge connector.
I'm interested in seeing if I can minimally modify it to have a similar
memory map to the Altair 680 so that the Altair's PROM monitor could
run on it.
Thanks!
Chris
--
Chris Elmquist
> From: Grant Taylor <cctalk at gtaylor.tnetconsulting.net>
>
> I wince at the idea of running with QIC tape. But my experience is with
> QIC-80 tapes of the '90s which were so unreliable as to be in the same
> category as AOL floppy disks during the late '90s around the transition
> to CD-ROMs. As in I would trust an AOL floppy disk to better hold my
> data for a week than I would a QIC-80 tape to hold data for a month,
> much less a year. ...and I didn't even trust an AOL floppy to go from
> computer to computer for 5 minutes. -- Talk about a race to the bottom
> for quality.
I wish I'd kept some. I had some AOL CDs from slightly later that made decent coasters for decades. Although I guess with the shutter, the floppy wouldn't really have made a very good coaster.
Adam
Is anyone familiar with the IBM 6731 Diskette Module from around 1984 which
gave the IBM Electronic 85 and 95 Selectric Typewriters the ability to store
created documents to a 5.25" floppy diskette?
There was also a 5.25" diskette which was nicknamed "IPL" for "initial
program load", and an interface board which was installed into the
typewriter and was referred to as the "IBM Typewriter Modularity Option".
I do not have any images of the IBM 6731, but I do have an image capture
>from the installation and operations manual, posted here:
https://www.dropbox.com/s/us8aely530s8p3a/6731diskettemodule.jpg?dl=0
You do not need a Dropbox account to view the image. Simply click on the X
of the login pop up and it will disappear.
Unfortunately, the only copy of this product manual I ever found was on
eBay. I purchased it last month, paid USPS priority mail shipping with
tracking and the post office lost it. :/
Thanks
Don Resor
Is anyone familiar with the IBM 6731 Diskette Module from around 1984 which
gave the IBM Electronic 85 and 95 Selectric Typewriters the ability to store
created documents to a 5.25" floppy diskette?
There was also a 5.25" diskette which was nicknamed "IPL" for "initial
program load", and an interface board which was installed into the
typewriter and was referred to as the "IBM Typewriter Modularity Option".
I do not have any images of the IBM 6731, but I do have an image capture
>from the installation and operations manual, posted here:
https://www.dropbox.com/s/us8aely530s8p3a/6731diskettemodule.jpg?dl=0
You do not need a Dropbox account to view the image. Simply click on the X
of the login pop up and it will disappear.
Unfortunately, the only copy of this product manual I ever found was on
eBay. I purchased it last month, paid USPS priority mail shipping with
tracking and the post office lost it. :/
Thanks
Don Resor
Looking for CONAR CCTV? TV camera CONAR WERE KITS FROM NATIONAL RADIO COMPANY want books parts assembled units whole units? broken units-- I lust for one in the box un-assembled too! anything anything anything? related? toi this? camera? collecting up stories and folklore from others that may have? built one, owned one or? even just lusted? for? one!reply using the? following? ??SMECC CONAR TV CAMERA HISTORY PROJECT?? ? ?as? email reply? title? and? send? to?couryhouse at aol.comdrop me a line off list? with? first? word? CONAR? in subj. line? thx....Thanks in advance and stay well....Ed Sharpe? Archivist? for? SMECC