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101090 discussions

Front Panel - Update. - PDP=8/i and PDP-8/l - Bezels - PDP-11

by tdk.knight＠gmail.com

8i I want one for my panel rebuild project On Aug 12, 2016 3:49 AM, "Rod Smallwood" <rodsmallwood52 at btinternet.com> wrote: Hi Guys Well my panels made to VCF. I have had some feedback and I expect more. Currently I have stock of PDP-8/e (Types A and B) , PDP-8/f and PDP-8/m. PDP-8/i should be out of manufacturing by now. Next up is PDP-8/L. -++++++++++++++++++++++++++ Order the above now ++++++++++++++++++ Due to our house remodeling and holidays at the silk screen studio it was quiet up until this week.. However now things have started up again. I'm about to revisit the PDP-8 bezel project. The prototype had a few issues but nothing major. I should have a painted example shortly. Once the PDP-8/L batch are safely in the stock room it will be time to start on PDP-11 panels. +++++++++++++++++++++++ Please register interest in bezels and PDP-11 panels ++++++++++++++++ Rod (Panelman) Smallwood

10 years, 1 month

Tape imaging

by COURYHOUSE＠aol.com

yep think 31 is right. have RCA tr-5 quad unit looking for more quad recorders always can swap some computer stuff! Anyway the fellow I get the tr-5 from... he alsoscrapped a tr-4 and I have bies of parts when I can access the parts will check for motors! ed# In a message dated 8/11/2016 10:58:56 P.M. Pacific Daylight Time, cclist at sydex.com writes: On 08/11/2016 10:07 PM, couryhouse wrote: > > > Chuck we have tape.... we also have one of the 30 something track > heads at smecc..... I guess won would have to build the motorized > wingaxas... to pull the tape. ... the electronics can be recreated... > We figure the head is the hard part..... ha! and a empty take up > reel! Anyone habe one?Ed www.smecc.org 31 tracks if I read the manual right. The tape itself is a mylar sandwich, so it should be plenty durable. Reel motors should be no great deal--maybe you could scavenge them from an old Ampex Quadruplex VTR... --Chuck

10 years, 1 month

SWTPC 6800

by vintagecomputer＠bettercomputing.net

Yes.. I tried 7 bits.. different parity settings, speeds etc. ?Couldn't quite nail it down. ?In every tutorial online for the 6800 being used with PC terminal, they go 8 N 1.. nobody mentions specifically if you are supposed to use hardware or xo/off or nothing though. ?So that's another thing. ?I'm also confused because some docs mention baud rate settings for the cpu board? I'm also not sure if bad RAM or bad TTL etc could be contributing to just throwing out random junk too. Sent from my Samsung device -------- Original message -------- From: Dave Wade <dave.g4ugm at gmail.com> Date: 2016-08-04 11:33 PM (GMT-08:00) To: "'General Discussion: On-Topic and Off-Topic Posts'" <cctalk at classiccmp.org> Subject: RE: SWTPC 6800 "Random Stuff" on serial ports can be a speed, data-bits, or even parity mis-match. I assume you have tried tweaking these? Dave > -----Original Message----- > From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Brad H > Sent: 05 August 2016 06:58 > To: 'General Discussion: On-Topic and Off-Topic Posts' > <cctalk at classiccmp.org> > Subject: RE: SWTPC 6800 > > I think this 6800 is live but I am being dogged by my inabilities when it comes > to cabling.? I'm going to purchase a 'proper' db25 female connector and the > molex pins for the MP-S connector and solder it up.? I tried sort of using > jumper wires to make it go.? When I turn the 6800 on, the PC terminal I'm > using reacts by producing single or strings of random characters. > According to the SWTPC 'system checkout' stuff, if I get anything at all > showing up on the terminal it usually means the 6800 is alive.? Based on the > notes written on the MP-S, I'm confident I have the correct baud rate and bit > (8) and parity (1) settings, but alas, doesn't seem to work.? When I ran into > this sort of thing with MSI 6800 it turned out the baud rate switch on the > serial card wasn't correct, despite factory labelling.? That might be the case > here but not really sure how to sort it. > > -----Original Message----- > From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Paul Birkel > Sent: Thursday, August 4, 2016 12:29 PM > To: 'General Discussion: On-Topic and Off-Topic Posts' > <cctalk at classiccmp.org> > Subject: RE: SWTPC 6800 >

10 years, 1 month

Tape imaging

by couryhouse＠aol.com

Chuck we have tape.... we also have one of the 30 something track heads at smecc..... I guess ?won would have to build ?the ?motorized ?wingaxas... to pull the tape. ... the electronics can be recreated... ?We figure the head is the hard part..... ha! ?and a empty take up reel! Anyone habe one?Ed www.smecc.org Sent from my Verizon, Samsung Galaxy smartphone -------- Original message -------- From: Chuck Guzis <cclist at sydex.com> Date: 8/11/16 21:21 (GMT-07:00) To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Subject: Re: Tape imaging On 08/11/2016 07:36 PM, Al Kossow wrote: > One of the highest projects I have in the queue is getting one of > John's M4 9914V drives with 18 track MR heads running in my new lab > at CHM. I've always wondered how far someone would go to retrieve data from media that's really off the beaten path.? Suppose someone found a box of tapes from an old Honeywell Datamatic mainframe.? Huge reels, 3 inches wide with heaven knows how many channels... --Chuck

10 years, 1 month

the value of old test and repair equipment

by jzatar2＠illinois.edu

>I really like my old test gear and yes, it just seems right to be restoring >vintage computers with vintage instruments. HP scopes, logic analyzers, >DVMs; function generator; Tek scope, frequency counter; as well as just >'sundry'. But I did break down and buy a DDS frequency generator to work >on my VHF/UHF ham gear. > >On Sat, Jul 30, 2016 at 6:07 PM, drlegendre . <drlegendre at gmail.com <http://www.classiccmp.org/mailman/listinfo/cctalk>> wrote: > >>* In fact, the value of old test gear varies tremendously.. *>>>>* Vacuum tube testers of certain makes & models are near the top of the food *>>* chain, with clean, working examples pulling $1500+ (USD) on a very regular *>>* basis. *>>>>* There's also a strong following for much 'classic' audio analysis gear (HD *>>* meters, ID meters, spectrum analyzers, etc.) some very fine multi-meters *>>* and anything really hi-end like General Radio, Breull & Kejjr, HP, and so *>>* forth. *>>>>* Some very early examples from the 1910s to 30's also pull good value simply *>>* for visual appeal. Much of this gear is resplendent with embossed, enameled *>>* panels, sculpted Bakelite knobs, large meter movements and an overall Art *>>* Deco styling. *>>>>* Seen a nice Supreme Diagnometer recently? Or any of the 40s-70s era English *>>* made tube testers, like the AVO? Hickok also made a series of bench VTVMs *>>* with massive chromed meters, designed to be large enough that they can be *>>* read from many feet away.. those are beautiful for display, and guess what *>>* - they work great, too! *>>>>* On Thu, Jul 28, 2016 at 5:24 PM, Dale H. Cook <radiotest at juno.com <http://www.classiccmp.org/mailman/listinfo/cctalk>> wrote: *>>>>* > At 03:52 PM 7/28/2016, Electronics Plus wrote: *>>* > *>>* > >... does as-is old test and repair equip that won't be particularly *>>* cheap *>>* > have interest to you guys? *>>* > *>>* > It depends entirely on the make and model of equipment. I always have a *>>* > laundry list of stuff I am looking for - one of the reasons why I bring *>>* my *>>* > tablet to meets. *>>* > *>>* > Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA *>>* > http://plymouthcolony.net/starcity/radios/index.html <http://plymouthcolony.net/starcity/radios/index.html> *>>* > *>>* > *>>> > > >-- >Ian S. King, MSIS, MSCS, Ph.D. Candidate >The Information School <http://ischool.uw.edu> >Dissertation: "Why the Conversation Mattered: Constructing a Sociotechnical >Narrative Through a Design Lens > >Archivist, Voices From the Rwanda Tribunal <http://tribunalvoices.org> >Value Sensitive Design Research Lab <http://vsdesign.org> > >University of Washington > >There is an old Vulcan saying: "Only Nixon could go to China." All this talk of older test equipment reminds me of the HP 4261A LCR bridge I repaired a while back, last winter I think. My dad found the 4261A in the garbage years ago, and it seemed to work fine, until one day he powered it up and the display showed garbage. He decided to open it up, and noticed some uncovered windowed EPROMs. Knowing that EPROMs sometimes flip bits in their old age, we decided that was the first place we would look. We were also able to locate the full HP service manual in PDF form for the instrument which helped tremendously. In typical HP fashion, it had full theory of operation, schematics, state diagrams, etc. Now, I have an EPROM burner that does your typical JEDEC pinout parts, 27 series and such. The issue is that these were Intel i1702A's from the early 70's I think. Not only are 1702's a totally different pinout, but they run on 14V (a +5V, and a -9V rail, with no connected ground, this is how intel got TTL levels on a MOS chip at the time). The 4261A has a total of 4 1702's, two of which form a finite state machine which controls the instrument, while the other two perform display decoding. I had to pull out my dad's DeVry Console 80, which has adjustable positive and negative supplies, and I manually clocked out the data and compared the contents to a dump I found online. I started with the state machine EPROMs, and compared the data. I did find a few discrepancies, but there was too much difference to have been bit rot. Given the sudden nature of the issue, I would have expected one, at most a couple bit flips, or something much more drastic (like total chip failure). Upon reading through the state diagrams in the HP manual, I noticed that there was a change noted in the state diagram between certain minor revisions of the 4261A. I looked at what the changes were, and deduced that my ROMs were in fact correct for the serial number prefix. At a dead end with the EPROMs, I decided to see if the state machine was even running at all. I used a DVM in DC mode, and measured perfect TTL ones and zeroes on all the state number outputs, which means those outputs weren't changing: the state machine was stuck. I wrote down the state it was stuck in and referred to the state diagram. I noticed something interesting. The state machine in the 4261A is able to evaluate simple conditions and control flow based on those. The state path to get to the state that the FSM was stuck on meant the FSM was always taking one of the conditional paths (always true, or always false, I don't remember which). At that point, I started looking into the condition circuitry, tracing out the path, checking IC's as I worked my way back, until I made it back to 1/2 of a 7474 which had a set input that was stuck active (low). This pin went to a pullup resistor, and nothing else in our unit (certain options used this pin, but not ours). We desoldered the IC, and sure enough, that pin was shorted to ground internal to the chip. We replaced it with a 74LS74, and the 4261A has been working great ever since, even with the original 40 year old 1702's. Also, on the topic of interesting HP products, and perhaps my personal favorite so far, is the HP dynamic signal analyzer 35670A. This instrument can perform all sorts of cool measurements. It can produce a test signal, and measure two different points in the circuit being measured. The measurement input channels give you a complex number phasor of the measured signal, which means you can do all sorts of cool measurements of networks, especially since you can do complex number math with the equation support of the instrument. The signal generator will perform sweeps too, of course. This was very useful determining whether the speaker crossovers my dad built were working as intended (actually they weren't, and this instrument helped us uncover a problem). We also used this to do inductor and capacitor characterization. There are all sorts of applications this instrument is good for. Joe Zatarski

10 years, 1 month

SWTPC keyboard foil patterns

by vintagecomputer＠bettercomputing.net

Hey guys, In Don Lancaster's 'Low cost keyboard and ascii encoder' article (Apr 1974), he mentions in the parts list that the SWTPC keyboard mentioned in the article had foil patterns available, full size, free on request. ?I was wondering if anyone out there had them or knew where they might be found. ?I checked SWTPC and Tinaja but they only have the article. ?I've emailed Don in case he had them but probably doubtful. Reason I ask is I was rather pleased with how my original TVT reproduction boards turned out, and I have a second CT1024 terminal here in need of a keyboard. ?Rather than rigging something up I thought maybe I could just recreate the PCB. ?I can already make the keycaps and the switches themselves are not beyond my ability either. Many thanks in advance if anyone has these. Brad Sent from my Samsung device

10 years, 1 month

Tape imaging

by shadoooo＠gmail.com

Hello Andreas, nice to see you here from time to time. I too have two TSZ07, but both had problems with the PSU after some time of good working condition. The problem was always related, as indirect cause, to bad electrolytic capacitors, however the effect was always bad. The first one in the end became somehow over-stressed and had a transistor burned to short circuit; replaced the transistor, and all the capacitors, it was ok. After the repair operation, one of the motors lost the magnet inside, so I had to dismount it, open it carefully, put the magnet in place with wood parts to keep it in the right position, reglue the magnet with acrylic glue, remount. Worked! The second one began suddenly to oscillate badly, so on the 5V output there were peaks from 0V to 15-20V... It remained in the bad state for just 3-5 seconds, then I turned on 220V. Too bad, a microprocessor on the control board was fried. As I didn't find any schematic at the time (and not one so far), it took me a life with the bare oscilloscope to understand which component was defective, ordered it form the US, desoldered with hot air, resoldered, et voila, it became to life again... Worked, but I paid more for the repair / components than what I paid for the drive... I know also Holm has such a drive, again problems with the PSU... overheating. So be warned: replace all the relevant capacitors before operate the drive, to avoid problems. If you want and have some patience, I could take some pictures to show you what parts are delicate and what not. The PSU inside has two boards, one is high-voltage stage, the other has the main transformer and the low-voltage stage. It produces IIRC -12V, +5V (standby), +5V (high current), +12V, +37V. To test the PSU alone, you need to connect a resistor between two pins of a connector (I should double-check in case you want to know), otherwise it will not power-up, only standby voltage will be present, but it's not supplied by the switching high-power circuit. I recommend a test of one hour or more with load resistors (or lamps) and voltage monitoring to test the effective operation. Let me know if you need some help. (out of band data): do you have some information about trips to Munchen or somewhere in Bayern or Osterreich? Didn't heard of you anymore lately... We still have the drive swap to organize! Please let me know. Thanks Andrea

10 years, 1 month

Tape imaging

by couryhouse＠aol.com

Have the tape sets from the phx univac operations center that need to be imaged some day!Ed# Sent from my Verizon, Samsung Galaxy smartphone -------- Original message -------- From: Al Kossow <aek at bitsavers.org> Date: 8/10/16 17:10 (GMT-07:00) To: cctech at classiccmp.org, "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Subject: Re: Tape imaging Related, since it hasn't been mentioned on this list. Tom Hunter just got a release from CDC for the use of CDC software for non-commercial use, so any CDC tapes out in the wild are going to be of great interest. On 8/10/16 6:22 AM, aswood at t-online.de wrote: > Now I do have a big pile of CDC, DEC, HP, Convex and IBM tapes and I'd like to create tape images to file to save the tapes content.

10 years, 1 month

"RAM Drives" Elite 5H/10H Hard Drives for Apple ][

by marvin＠west.net

I ran across a manual from "Ram Drives" company that apparently made hard drives. They were based in Goleta, CA (just north of Santa Barbara) which is what really caught my attention. My *guess* is they made/provided hard drives to Lobo Drives for their hard drive/floppy disk combination. I *think* I have either two or three of these units, but am unwilling to power them up without knowing a LOT more about how to do it safely. Because I believe they came from Lobo Drives, I suspect they may have a lot of interesting source code/programs that Lobo dealt with. Long way of asking, has anyone heard of "Ram Drives" company based in Goleta, CA and have any more information on them?

10 years, 1 month

good news from me

by cctalk-bounces＠classiccmp.org

Hi friend! I wanted to tell you something really nice, please read it here <http://compare.kitefamily.us/aezymg> Hope this helps, cctalk-bounces at classiccmp.org

10 years, 1 month

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