test-drb

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101090 discussions

by go＠aerodesic.com

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,

4 years, 2 months

2 microvax 3800's for sale

by lyokoboy0＠gmail.com

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.

4 years, 2 months

Searching for information reg. IBM 3979 (Expansion module for 3179G / 3192G coax (3270) terminal)

by romietoo9ibi＠xx.vu

Hi! I am the proud owner of a 3192G coax terminal. As I have recently learned, there is an expansion module for the terminal that allows you to attach a mouse and a IEEE-488 pen plotter to the terminal. Some information about it can be found at [1] and [2]. I am searching for people who are in possession of this expansion unit, out of interest how the PCB looks, etc. If you have one, please respond. -Alex [1] http://bitsavers.org/pdf/ibm/3192/GA18-2590-1_IBM_3192-G_Color_Graphics_Dis… [2] http://www.bitsavers.org/pdf/datapro/alphanumeric_terminals/Datapro_C25_IBM…

4 years, 2 months

Old Micro Memory core board

by go＠ao-cs.com

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

4 years, 2 months

Question about DECtape formulation

by jnc＠mercury.lcs.mit.edu

> 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

4 years, 2 months

Typing in lost code

by mark.kahrs＠gmail.com

Has anyone ever used Amazon Mechanical Turk to employ typists to type in old listings of lost code? Asking for a friend.

4 years, 2 months

mystery S-100 available

by sieler＠allegro.com

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!

4 years, 2 months

Question about DECtape formulation

by jnc＠mercury.lcs.mit.edu

> 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

4 years, 2 months

Typing in lost code

by jnc＠mercury.lcs.mit.edu

> 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

4 years, 2 months

PDP-8 clone built by Canadian company Consolidated Computer Inc

by rodsmallwood52＠btinternet.com

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

4 years, 2 months

Compaq Portable brightness knob

by dave＠661.org

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?

4 years, 2 months

Building a BA08 for a pdp8/L

by cz＠alembic.crystel.com

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

4 years, 2 months

VAX 780 on eBay

by jnc＠mercury.lcs.mit.edu

> 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

4 years, 2 months

WARNING: Clear QIC Tape Bands

by lists＠glitchwrks.com

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

4 years, 2 months

Source for replacement caps in H744 regulators

by robert.jarratt＠ntlworld.com

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

4 years, 2 months

Tiny PDP-11/73 system for sale

by stephen.m.pereira.sr＠gmail.com

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

4 years, 2 months

Screws for a Compaq Portable keyboard

by dave＠661.org

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?

4 years, 2 months

DECnet/10 manuals?

by paulkoning＠comcast.net

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

4 years, 2 months

Tiny PDP-11/73 system for sale

by stephen.m.pereira.sr＠gmail.com

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

4 years, 2 months

Sun 3/260 on eBay; Boston area

by pschow＠gmail.com

Local pickup only. https://www.ebay.com/itm/265510502961

4 years, 2 months

seeking Motorola M68MM01A2 documentation

by chrise＠pobox.com

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

4 years, 2 months

AOL diskettes

by athornton＠gmail.com

> 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

4 years, 2 months

IBM 6731 Diskette Module

by organlists1＠sonic.net

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

4 years, 2 months

IBM 6731 Diskette Module

by organlists1＠sonic.net

4 years, 2 months

Looking for CONAR CCTV TV camera CONAR WERE KITS FROM NATIONAL RADIO COMPANY

by couryhouse＠aol.com

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

4 years, 2 months

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