test-drb March 2016

test-drb@ccmp.vtda.org

189 participants
229 discussions

by rodsmallwood52＠btinternet.com

Hi Guys I have now seen the production batch of 8/e A and B. panels. They will ship next week after inspection and packing. 8/f and 8/m will be next up. If you have placed an order for any of the above please confirm your shipping address. When I switched to the textured front I ordered a few more blank panels. Depending on the yeild after final inspection there may be a few extras available. Regards Rod

8 years, 1 month

Free Sinclair QL emulator

by lproven＠gmail.com

While experimenting with Sinclair emulators on Ubuntu last night, I made 2 discoveries which might interest folk here. First, the author of perhaps the premium Sinclair QL emulator for Windows, QPC, has made it unrestricted freeware. The news is from mid-2014 but I'd missed it. Both QPC1 and QPC2 are now available free of charge. I found this news via Dilwyn Jones' site, here: http://www.dilwyn.me.uk/emu/ This is the direct download & info site for QPC: http://www.kilgus.net/qpc/index.html They come bundled with SMSQ/e, the final-generation QL OS, derived >from QDOS, complete with bootable hard disk images. The second discovery was that QPC2 for Windows installs and runs flawlessly under WINE on 64-bit Ubuntu. :-) -- Liam Proven ? Profile: http://lproven.livejournal.com/profile Email: lproven at cix.co.uk ? GMail/G+/Twitter/Flickr/Facebook: lproven MSN: lproven at hotmail.com ? Skype/AIM/Yahoo/LinkedIn: liamproven Cell/Mobiles: +44 7939-087884 (UK) ? +420 702 829 053 (?R)

8 years, 1 month

Needs help w/ diagnosing and hopefully repairing of a DEC Tape Drive

by shadoooo＠gmail.com

Hello, I have two TSZ07 here. As they were sold as "for parts" obviously they both needed some repair. One of the two had severe mechanical problems. One motor had a loose unglued magnet inside, so there was a motor fault error, and the motor couldn't rotate freely, making a rattle noise inside when operated by hand. Of course it was better not to act on that before repair, to avoid to damage the magnet. To repair it I needed to unscrew the reel (in my case the front reel with the loading mechanism to hold the interchangeable reel with the tape), unscrew the motor from the frame, then remove the tacho (very delicate!) and then finally open the motor. The loose magnet appeared to be originally glued to the metal housing with cyanoacrilic glue, so I positioned it by hand aligning it with the remaining glue traces on the housing, held it in place with a clamp tool then finally added new abundant glue all around, letting it to flow under the magnet. Then waited for 24 hours and reassembled. The tacho wheel needed to be cleaned, as the very thin steel growth with some oxide in the small holes, not being optically open enough to work. You can see how this wheel is delicate... maximum care not to bend or crack it! It worked! PS= check very carefully your PSU, as both drives had severe problems on it, they are very prone to fail! One simply ceased to operate after some time, and needed some component replacement to work again. The second one did worst! It did fail beginning suddenly to put out pulsed voltage (8-10V peak) on the 5V. I turned it off within a couple of seconds, but unluckly it fried some ICs on the digital board... It had to change two Z80-serie ICs on the board, to let it finally work... And of course to repair the PSU and test it for some hours with load before testing it again with the real hardware. Andrea

8 years, 1 month

PDP-11/20 vd one that just says pdp 11 what are the date differences?? OEM?

by michael.99.thompson＠gmail.com

> > Date: Fri, 26 Feb 2016 07:21:13 -0500 (EST) > From: jnc at mercury.lcs.mit.edu (Noel Chiappa) > Subject: Re: PDP-11/20 vd one that just says pdp 11 what are the date > differences?? OEM? > > That's an -11/15, then. The -11/20 has a KA11 processor. So the front panel > just says "pdp-11"? > > Noel > It was an OEM system and has a Applied Color Systems, Inc. front panel. The system is missing all of the boards and backplanes. Someday we will find enough parts to put it back together. -- Michael Thompson

8 years, 1 month

Precision Instruments PI1200 7 track tape drive, interest anyone?

by gerry＠absoluteimaging.ca

Hello Mattis, We do have interest in the 7 track drive. Is it still available? Gerry Schlosser Absolute Imaging Inc. Suite 400, 1011-1st Street S.W. Calgary, Alberta, Canada T2R 1J2 Gerry at absoluteimaging.ca 1-403-209-6846

8 years, 1 month

Needs help w/ diagnosing and hopefully repairing of a DEC Tape Drive

by cctalk＠fahimi.net

In my continuing quest for a 9-track drive I got my hands on DEC TSZ07-CA w/ a narrow SCSI interface that was supposedly "tested working". On arrival to me I found it wrapped in a thin layer of bubble wrap w/ some broken piece of Styrofoam thrown in for "packing". As one can imagine the drive did not farewell. The outer desktop housing is cracked in multiple places but still serviceable. The drive itself came with parts rattling on the inside. I opened it up, cleaned things up a bit, and put things back together so that now the drive powers up, starts self test, and then errors out w/ a "50 - Motor Fault" error. I have checked the wires and reseated everything that I can see. I've also cleaned all the sensors, blown out the dirt, etc. etc. The problem persists so I am going to assume a component was damaged in the shipping. I ran the tests indicated in the tech manual and I get the following results: generally the supply motor starts to turn but stops even before making a full revolution. Incidentally if I manually turn the reel it turns fine and the tape securing arms open and close appropriately. When running the dx tests sometimes I can get the uptake motor to spin up at full speed and once even had the supply motor spin up at full speed. Per the tech manual if restarting the system does not make the problem go away the next step would be to replace the motor.... Google fu has not turned up much - so before I declare this a very heavy paper weight anyone have any ideas? Thanks! -Ali

8 years, 1 month

MM11-U G235 bias/strobe jumpers

by jnc＠mercury.lcs.mit.edu

So, the MM11-U manual (EK-MF11U-MM-003) describes (pg. 3-12) a set of jumpers (W5-W7) on the G235 card (X and Y selection line current generators - those for the inhibit lines are on the G114) which adjust the bias current for the selection line generators. It goes on to say: "Jumpers W5-W7 are factory cut to adjust the bias current to its optimal value and they should not be changed." There's apparently a similar adjustment for the timing of the sense strobe (although I can't find the description of that circuitry). So I have two observations, based on this. The first is that the original procedure for setting those jumpers is likely lost, it's probably only in some internal DEC documentation. The manual says (Section 5.4.2, "Sense Strobe Delay and Drive Current Adjustments"): "Correction of any failure in either the sense strobe delay or drive current circuits on the G235 module that would require reconfiguration of the jumpers within these circuits should _not_ be attempted in the field. Replace the faulty module with a spare G235 module and return the faulty G235 module to the factor for repair." These cards are old, component values may have drifted, and so perhaps these might need to be adjusted - but we'll need to work out a procedures for doing so, if so. We _do_ seem to have a test to know _if_ the bias current is properly adjusted - see Section 5.3.4, "Drive Current Checks", and also for the strobe delay (Section 5.3.3, "Sense Strobe Delay Checks"). So I guess in theory, if a G235 card fails one of these tests, we could change the smallest value jumper, and see if that made things worse or better, and then loop. So perhaps all is not lost. The second is that I was worried that these boards were 'tuned' to be part of a set. E.g. one of the components, in the circuit that the W5-W7 jumpers are part of, is a thermistor on the core stack board. I couldn't tell if the jumpers were just for dealing with component variations on the G235 board, or if they also include variation elsewhere - i.e. that MM11-U's came as tuned board sets which should not be 'mix and matched'. However, that second chunk of text I quoted alleviated that concern: apparently one _can_ replace one G235 with another, without swapping out all the boards in the set. Which means that the 'mixing and matching' that has happened to these boards since they were removed from their machines (I myself am guilty of this - I pulled a couple of MM11-U sets, and didn't carefully keep the boards in their original sets) has probably not caused any problems. Noel

8 years, 1 month

cctalk Digest, Vol 20, Issue 29

by fred＠MISER.MISERNET.NET

On Mon, 29 Feb 2016 cctalk-request at classiccmp.org wrote: > From: Murray McCullough <c.murray.mccullough at gmail.com> > Subject: Techno-savvy... > Message-ID: > <CAMvyYF-YXr8XFD4q9d1uZrOBBfUgnS=e=NTM8zSGTermw-tT2A at mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > What is a techno-savvy student? Can classic computers possibly give an > answer? I used early microcomputers in my electronics classroom I > taught in the 70?s. Computers back then were rather primitive, not > much better than calculators, but did mimic human learning ? well [story cut] I liked this story, reminded me of my education in the late 80's early 90's - I was the "computer go to guy" so instead of the shiny new PS/2's the district had recently purchased they "stuck" me witth the 5150 in the back that no one wanted to use. The things I was able to make that thing do with just two floppies.... :) > > So what is a techno-savvy student now: Conversant in using a > technological gadget to enhance his/her life? Or being able to build a > computing workstation in high school? Or for simply possessing a basic [chop] Whenever this comes up in the context of today's youth (where they tell me they'll take my job one day) I just have to laugh. The vast majority (not all, as that would be unfair, and I have met some younger than me folks that know their stuff) of youth today know how to USE the device, but not necessarily how to fix it if it breaks physically or logically (I'll leave out that fixing of these tablets/phones/pads physically is usually a board swap ....). As Kirk said in Star Trek II, The Wrath of Khan, "You have to learn WHY things work on a starship." Fred

8 years, 1 month

'motherboard' etymology

by jules.richardson99＠gmail.com

Does anyone know the origins of the term 'motherboard'? I've always associated it with computers and assumed that it started appearing somewhere around 1980, with the fading out of passive backplane systems and arrival of machines which put more functionality onto a 'core' PCB into which other cards were plugged. I don't recall ever seeing it used when referencing earlier big iron, but maybe I've just missed it. I had the case lid off a Fluke digital multimeter which hails from 1972 earlier, and was surprised to see it written as part of a warning there ("ensure that all cards are securely plugged into the motherboard before applying power", or similar - unfortunately I didn't grab a photo at the time). cheers Jules

8 years, 1 month

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test-drb March 2016