Re: DECTape head problem
You could try: http://www.jrfmagnetics.com/ Tom On Wed, Feb 9, 2022 at 3:06 PM Gary Oliver via cctalk wrote: > On 2/8/22 14:14, Wayne S via cctech wrote: > > Searched a lille bit for Western Magnetics. Here’s a site that has some > surplus heads, even a western magnetics onebut probably not the correct > one. There is a corporate charter record for Western Magnetics in Minnesota > dated 1964. Maybe this is the same company. There’s also a tape head from > Michigan Magnetics. Maybe a merged company? > > > > https://www.surplussales.com/Equipment/magnetic-tape.html > > > > > > Sent from my iPhone > > > > On Feb 8, 2022, at 13:05, Ron Pool via cctech > wrote: > > > > > > So it sermsdectape heads are special. I don’t think Dec would have the > desire to make them internally so they probably contractef with a company > already set up to do that. Who were the big tape head manufacturers at that > time? Does anyone know? > > > > A photo of the back of a TU56 DECtape head can be seen at > https://www.pdp8online.com/tu56/pics/head_label.shtml?small . > > The head has a label on it that reads: > > Western Magnetics > > Glendale Calif. > > Record > > 7282 > > > > I've never seen a TU56 in person and have no idea if they have separate > read, write, and erase heads or some other combo. The "Record" notation on > the above head's label hints to me this might be a write head. > > > > I found that and other DECtape photos at > https://www.pdp8online.com/tu56/tu56.shtml . > > > > -- Ron > > > > > Thanks. Hadn't seen the Minnesota information. Found some references > but not actual company info. Did find a reference somewhere it Canada, > but I couldn't tell if it was original or successor company. At any > rate, no web presence nor telephone numbers found (yet.) > > I've dealt with the SurplusSales (of Nebraska) many times. His prices > are usually pretty high (not obscene, but just not 'surplus' prices I'm > used to.) However, he is a first-rate dealer and when he says something > is so, you can count on it. Never had problem with anything I was > willing to *PAY* for. I scanned the list you provided and found only a > few 'digital' devices, unfortunately. I suspect from 7 and 9 track mag > tape drives. I will scan his site and send him a ping so he'll be on > the lookout. > > -Gary > > >
Re: DECTape head problem
On 2/8/22 14:14, Wayne S via cctech wrote: Searched a lille bit for Western Magnetics. Here’s a site that has some surplus heads, even a western magnetics onebut probably not the correct one. There is a corporate charter record for Western Magnetics in Minnesota dated 1964. Maybe this is the same company. There’s also a tape head from Michigan Magnetics. Maybe a merged company? https://www.surplussales.com/Equipment/magnetic-tape.html Sent from my iPhone On Feb 8, 2022, at 13:05, Ron Pool via cctech wrote: So it sermsdectape heads are special. I don’t think Dec would have the desire to make them internally so they probably contractef with a company already set up to do that. Who were the big tape head manufacturers at that time? Does anyone know? A photo of the back of a TU56 DECtape head can be seen at https://www.pdp8online.com/tu56/pics/head_label.shtml?small . The head has a label on it that reads: Western Magnetics Glendale Calif. Record 7282 I've never seen a TU56 in person and have no idea if they have separate read, write, and erase heads or some other combo. The "Record" notation on the above head's label hints to me this might be a write head. I found that and other DECtape photos at https://www.pdp8online.com/tu56/tu56.shtml . -- Ron Thanks. Hadn't seen the Minnesota information. Found some references but not actual company info. Did find a reference somewhere it Canada, but I couldn't tell if it was original or successor company. At any rate, no web presence nor telephone numbers found (yet.) I've dealt with the SurplusSales (of Nebraska) many times. His prices are usually pretty high (not obscene, but just not 'surplus' prices I'm used to.) However, he is a first-rate dealer and when he says something is so, you can count on it. Never had problem with anything I was willing to *PAY* for. I scanned the list you provided and found only a few 'digital' devices, unfortunately. I suspect from 7 and 9 track mag tape drives. I will scan his site and send him a ping so he'll be on the lookout. -Gary
Re: DECTape head problem
> On Feb 8, 2022, at 5:14 PM, Wayne S via cctech wrote: > > Searched a lille bit for Western Magnetics. Here’s a site that has some > surplus heads, even a western magnetics onebut probably not the correct one. > There is a corporate charter record for Western Magnetics in Minnesota dated > 1964. Maybe this is the same company. There’s also a tape head from Michigan > Magnetics. Maybe a merged company? > > https://www.surplussales.com/Equipment/magnetic-tape.html Those all look like audio heads, nothing even vaguely resembling a DECtape head. paul
Re: DECTape head problem
> On Feb 8, 2022, at 4:04 PM, Ron Pool via cctech wrote: > >> So it sermsdectape heads are special. I don’t think Dec would have the >> desire to make them internally so they probably contractef with a company >> already set up to do that. Who were the big tape head manufacturers at that >> time? Does anyone know? > > A photo of the back of a TU56 DECtape head can be seen at > https://www.pdp8online.com/tu56/pics/head_label.shtml?small . > The head has a label on it that reads: > Western Magnetics > Glendale Calif. > Record > 7282 > > I've never seen a TU56 in person and have no idea if they have separate read, > write, and erase heads or some other combo. The "Record" notation on the > above head's label hints to me this might be a write head. > > I found that and other DECtape photos at > https://www.pdp8online.com/tu56/tu56.shtml . This picture https://www.pdp8online.com/tu56/pics/TU56_front.shtml?large shows the tape path clearly. There is just one head assembly that performs reading as well as writing. I don't know what "Record" refers to; the numbers near it look vaguely like a date code though not the usual year and week number. The maintenance manual (on Bitsavers) speaks of a "read/write head" and has an illustration that shows one of the head elements with a "read/write coil". So the implication is that (a) there isn't an erase head, and (b) the same head serves for read or write according to whether the coil is being driven or sensed. Come to think of it, I think erase heads are an aspect of audio tapes, not relevant to computer tapes. paul
Re: DECTape head problem
On 2/8/22 13:04, Ron Pool via cctech wrote: So it sermsdectape heads are special. I don’t think Dec would have the desire to make them internally so they probably contractef with a company already set up to do that. Who were the big tape head manufacturers at that time? Does anyone know? A photo of the back of a TU56 DECtape head can be seen at https://www.pdp8online.com/tu56/pics/head_label.shtml?small . The head has a label on it that reads: Western Magnetics Glendale Calif. Record 7282 I've never seen a TU56 in person and have no idea if they have separate read, write, and erase heads or some other combo. The "Record" notation on the above head's label hints to me this might be a write head. I found that and other DECtape photos at https://www.pdp8online.com/tu56/tu56.shtml . -- Ron Mine also says Western Magnetics, Glendale CA, but does not have a part number. Just serial numbers. At least I assume they are serial numbers "19984" and "19976". I've seen evidence that a few souls in the 50s managed to make magnetic heads from scratch (heck, Ivan Sutherland is claimed to have made a functioning magnet drum storage device when he was in 12th grade,) so give the modern world of CNC milling and availability of every manner of sheet metal via Internet searchers, I figured their just *might* be a possibility of growing one of these from scratch - tolerances (other than head gap) appear pretty generous, but I just don't have enough info to crack what the coil construction is to be. There may be enough information to do a stab at it, but I'm not sure I have the energy (or even the skill) to give it a credible effort. I've seen evidence of 'head repair' services, but I doubt they include digging out the wires from solid epoxy. Any information available would be appreciated. -Gary
Re: DECTape head problem
On 2/8/22 13:04, Ron Pool via cctech wrote: So it sermsdectape heads are special. I don’t think Dec would have the desire to make them internally so they probably contractef with a company already set up to do that. Who were the big tape head manufacturers at that time? Does anyone know? A photo of the back of a TU56 DECtape head can be seen at https://www.pdp8online.com/tu56/pics/head_label.shtml?small . The head has a label on it that reads: Western Magnetics Glendale Calif. Record 7282 I've never seen a TU56 in person and have no idea if they have separate read, write, and erase heads or some other combo. The "Record" notation on the above head's label hints to me this might be a write head. I found that and other DECtape photos at https://www.pdp8online.com/tu56/tu56.shtml . -- Ron Mine also says Western Magnetics, Glendale CA, but does not have a part number. Just serial numbers. At least I assume they are serial numbers "19984" and "19976". I've seen evidence that a few souls in the 50s managed to make magnetic heads from scratch (heck, Ivan Sutherland is claimed to have made a functioning magnet drum storage device when he was in 12th grade,) so give the modern world of CNC milling and availability of every manner of sheet metal via Internet searchers, I figured their just *might* be a possibility of growing one of these from scratch - tolerances (other than head gap) appear pretty generous, but I just don't have enough info to crack what the coil construction is to be. There may be enough information to do a stab at it, but I'm not sure I have the energy (or even the skill) to give it a credible effort. I've seen evidence of 'head repair' services, but I doubt they include digging out the wires from solid epoxy. Any information available would be appreciated. -Gary -- -Gary
RE: DECTape head problem
> So it sermsdectape heads are special. I don’t think Dec would have the desire > to make them internally so they probably contractef with a company already > set up to do that. Who were the big tape head manufacturers at that time? > Does anyone know? A photo of the back of a TU56 DECtape head can be seen at https://www.pdp8online.com/tu56/pics/head_label.shtml?small . The head has a label on it that reads: Western Magnetics Glendale Calif. Record 7282 I've never seen a TU56 in person and have no idea if they have separate read, write, and erase heads or some other combo. The "Record" notation on the above head's label hints to me this might be a write head. I found that and other DECtape photos at https://www.pdp8online.com/tu56/tu56.shtml . -- Ron
Re: PDP-11/34 CPU PROMS
On Tue, Feb 8, 2022 at 7:04 PM Warner Losh wrote: > I found > https://deramp.com/downloads/mfe_archive/011-Digital%20Equipment%20Corporation/08%20PDP-11/01%20PDP-1104-1134/05%20PDP-1104-1134%20Microcode/ > which has the source code... > > But I couldn't find the tools to use these files to create microcode > images. > There's a small chance that the tools.tar.gz link on http://www.ak6dn.com/PDP-11/M9312/ has these, but that's for a different module so who knows... > http://filedump.theglitchworks.net/software/vintage/dec/roms/bdv11_upgrade/ > has a number of ROM images. Don't know if they are the ones you want. What > are the XX-X-XX numbers on the PROMs you are looking for? > > Warner > > > On Tue, Feb 8, 2022 at 6:18 PM Rod Smallwood via cctalk < > cctalk@classiccmp.org> wrote: > >> Hi >> >> Jerry Walker and I have an 11/34 under restoration. >> >> We have run into a bit of a problem. >> >> On the M8266 CPU control board a defective 7404 (E111) has killed a >> bunch of the PROMs holding the microcode. >> >> Does anybody have or can get images of the PROMs on this board so >> replacement devices an be programmed. >> >> Rod >> >> >>
Need 8mm or DLT-II tape?
I have many 8mm tapes. A few are new. First comers get new ones. I have a few 8mm cleaning cassettes I have about a dozen DLT-II tapes. I have a Quantum DLT-II drive with wide SCSI LVD/SE interface I have some Ultrium LTO fibre-channel SCSI drives that were removed from a tape-mounting robot several years ago. I never used them in my computers. The mounting bracket for one was modified to have an internal power supply -- which might be inadequate. I have one LTO tape. I have a 5.25" floppy drive. Yours for the price of shipping, or local pickup OK. Van Snyder van.sny...@sbcglobal.net La Crescenta, CA
Re: PDP-11/34 CPU PROMS
I found https://deramp.com/downloads/mfe_archive/011-Digital%20Equipment%20Corporation/08%20PDP-11/01%20PDP-1104-1134/05%20PDP-1104-1134%20Microcode/ which has the source code... But I couldn't find the tools to use these files to create microcode images. http://filedump.theglitchworks.net/software/vintage/dec/roms/bdv11_upgrade/ has a number of ROM images. Don't know if they are the ones you want. What are the XX-X-XX numbers on the PROMs you are looking for? Warner On Tue, Feb 8, 2022 at 6:18 PM Rod Smallwood via cctalk < cctalk@classiccmp.org> wrote: > Hi > > Jerry Walker and I have an 11/34 under restoration. > > We have run into a bit of a problem. > > On the M8266 CPU control board a defective 7404 (E111) has killed a > bunch of the PROMs holding the microcode. > > Does anybody have or can get images of the PROMs on this board so > replacement devices an be programmed. > > Rod > > >
PDP-11/34 CPU PROMS
Hi Jerry Walker and I have an 11/34 under restoration. We have run into a bit of a problem. On the M8266 CPU control board a defective 7404 (E111) has killed a bunch of the PROMs holding the microcode. Does anybody have or can get images of the PROMs on this board so replacement devices an be programmed. Rod
Re: DEC AXV11-C analog board
On 2/8/22 16:35, Douglas Taylor via cctalk wrote: On 2/8/2022 5:22 PM, Jon Elson via cctalk wrote: On 2/8/22 13:34, Douglas Taylor via cctalk wrote: Update on this: I did put together a battery and voltage divider to test the AXV11. The label on the A/D module says it brings the output from the multiplexer to one of the external pins. I was able to verify that the voltage applied to a couple of the A/D inputs makes it through the multiplexer when selected using the CSR. The next output available is from the Sample and Hold, and this is always pegged at +12v. Am I wrong to assume that the sample and hold will 'freeze' its output when the A/D go bit is set? Well, it will probably only hold the approximate voltage for a few seconds, but should be long enough to see on a voltmeter. Jon I was only using a voltmeter to look at it. I'm going to try 2 different measurements; (1) use a scope to look at the S signal on the AXV11 and see what it does over time, (2) look at the same S signal on the Data Translation board which seems to be working. The S will likely have a FET as the switch element, and those might be fairly easily damaged by external pulses. I opened up some comparable Xincom modules and made minor repairs. Jon
Re: DEC AXV11-C analog board
On 2/8/2022 5:22 PM, Jon Elson via cctalk wrote: On 2/8/22 13:34, Douglas Taylor via cctalk wrote: Update on this: I did put together a battery and voltage divider to test the AXV11. The label on the A/D module says it brings the output from the multiplexer to one of the external pins. I was able to verify that the voltage applied to a couple of the A/D inputs makes it through the multiplexer when selected using the CSR. The next output available is from the Sample and Hold, and this is always pegged at +12v. Am I wrong to assume that the sample and hold will 'freeze' its output when the A/D go bit is set? Well, it will probably only hold the approximate voltage for a few seconds, but should be long enough to see on a voltmeter. Jon I was only using a voltmeter to look at it. I'm going to try 2 different measurements; (1) use a scope to look at the S signal on the AXV11 and see what it does over time, (2) look at the same S signal on the Data Translation board which seems to be working.
Re: DEC AXV11-C analog board
On 2/8/22 13:34, Douglas Taylor via cctalk wrote: Update on this: I did put together a battery and voltage divider to test the AXV11. The label on the A/D module says it brings the output from the multiplexer to one of the external pins. I was able to verify that the voltage applied to a couple of the A/D inputs makes it through the multiplexer when selected using the CSR. The next output available is from the Sample and Hold, and this is always pegged at +12v. Am I wrong to assume that the sample and hold will 'freeze' its output when the A/D go bit is set? Well, it will probably only hold the approximate voltage for a few seconds, but should be long enough to see on a voltmeter. Jon
Re: Anyone live in Minneapolis?
> From: Steve at oldcomputers.net > There are some vintage tablets in Minneapolis (Eden Prarire) that would > like, but the seller will not ship. > Any help? When dealing with eBaiters who can't/won't ship, I have had good luck with PakMail (http://www.pakmail.com/); for a usually reasonable fee, they will go pick something up, package it properly, and ship it. In my experience with them, the shipping cost may not have been the absolute lowest possible I could have secured had I been on the spot, looking around, but.. I wasn't on the spot, looking around. And they went to the person's house, picked the thing up, and shipped it. Noel
Re: DEC AXV11-C analog board
On Sun, Feb 6, 2022 at 9:20 AM Douglas Taylor via cctalk wrote: > > Does anyone have any info on the A/D module? Who made it? Can you open > it up? Does XXDP have a test for this? http://www.bitsavers.org/pdf/dec/pdp11/xxdp/PDP11_DiagnosticHandbook_1988.pdf PDP11 DIAGNOSTIC HANDBOOK 1988, Page A-7: VAXAB0.BIC ADV11-C/AXV11-C A/D CONVERTER TEST
Anyone live in Minneapolis?
There are some vintage tablets in Minneapolis (Eden Prarire) that would like, but the seller will not ship. Any help? You will have to pay, pick up, and ship. I would do it for you! Thanks- Steve in CA
Re: DECTape head problem
> On Feb 8, 2022, at 2:53 PM, Wayne S via cctech wrote: > > Since so many audio tape players and computer magtape units were made it > would stand to reason that there has to be a stash somewhere of tape heads > and it’s just a matter of finding where they are. > Are there any part numbers on the dectape heads? The schematics are bound to show DEC part numbers, but how those translate into supplier part numbers is anyone's guess. Or perhaps they were made internaly by DEC? In any case, DECtape heads are unusual. Computer tapes are normally 1/2 inch wide (a few old tape drives had different widths, like the 14 track 1 inch CDC tape). But DECtape and LINCtape are 3/4 inches wide, with 10 head positions. Audio tapes are unlikely to be helpful; consumer reel to reel tape is 2 tracks (interleaved for when you flip over the reel?) 1/4 inch; professional decks might have 8 tracks or more on 1/2 or 1 or 2 inch wide tape, but I don't remember ever seeing 3/4 inch wide audio or instrumentation heads. paul
Re: DEC AXV11-C analog board
> On Feb 8, 2022, at 2:34 PM, Douglas Taylor via cctalk > wrote: > > Update on this: I did put together a battery and voltage divider to test the > AXV11. The label on the A/D module says it brings the output from the > multiplexer to one of the external pins. I was able to verify that the > voltage applied to a couple of the A/D inputs makes it through the > multiplexer when selected using the CSR. The next output available is from > the Sample and Hold, and this is always pegged at +12v. Am I wrong to assume > that the sample and hold will 'freeze' its output when the A/D go bit is set? You're correct, a S/H circuit is supposed to hold the value that was on its input at the time it was told to take the sample. Typically it won't hold it "forever"; S/H circuits have a hold time spec chosen so it is substantially longer than the time it takes the A/D behind it to complete its measurement. paul
Re: DEC AXV11-C analog board
Update on this: I did put together a battery and voltage divider to test the AXV11. The label on the A/D module says it brings the output from the multiplexer to one of the external pins. I was able to verify that the voltage applied to a couple of the A/D inputs makes it through the multiplexer when selected using the CSR. The next output available is from the Sample and Hold, and this is always pegged at +12v. Am I wrong to assume that the sample and hold will 'freeze' its output when the A/D go bit is set? At least the D/A's work on the AXV11 I have! Glass half full. Next tried the Data Translation DT2762 with the voltage divider source and this board appears to work correctly. What I was able to observe was by applying different voltages to the input I see different binary values in the DBR. The manual from bitsavers for this board lists a complete Macro diagnostic program in an appendix. Does anyone have an electronic copy of this Macro code? Or the compiled utility? Doug On 2/6/2022 1:55 PM, Jerry Weiss via cctalk wrote: These A/D systems use methods to isolate the sensitive analog signals from the electrical noise and ground plane of the computer. Typically a differential input is standard, so you will probably need wire up two inputs. If this is your first time with A/D, suggest you toggle in some code to trigger and report the A/D conversion repeatedly and use a small voltage battery with a potentiometer divider to drive the inputs. Most of the analog inputs should be high impedance and while not impervious, can take +- 30v w/o damage. Jerry On 2/6/22 11:43 AM, Douglas Taylor via cctalk wrote: Yes, I am putting 1 into the CSR to start the conversion and I do get a 200(8) indicating that the conversion is complete. I wonder if this means the A/D chip is OK but something else, like the multiplexer chip or gain amp is fried. On 2/6/2022 12:33 PM, Jerry Weiss via cctalk wrote: Are you triggering an A/D conversion via the CSR or external signal? Then check the A/D done bit. See EK-AXV11-UG-02 Chapter 4. Jerry On 2/6/22 11:20 AM, Douglas Taylor via cctalk wrote: I have one of these and would like to use it, however it appears to only partially work. Here is what I have found that works and what doesn't: 1. CSR and DBR are present and operational. 2. Jumpers set to 'factory'. 3. D/A portion works, can deposit codes in ODT and see voltages out on DAC pins that change depending on the octal value deposited in CSR+4 or +6. 4. A/D portion returns full scale code, either 3777 (2's compliment) or (offset binary) whether in the input is open or shorted to gnd. I think the problem is that the A/D inputs are not exactly protected and damage has occurred to this portion in the past. Does anyone have any info on the A/D module? Who made it? Can you open it up? Does XXDP have a test for this? Doug
