test-drb June 2020

test-drb@ccmp.vtda.org

158 participants
124 discussions

by charlesmorris800＠centurytel.net

On 6/21/20 10:41 AM, Jon Elson wrote: > On 06/20/2020 09:41 PM, Charles wrote: >> On 6/20/20 8:31 PM, Jon Elson wrote: >>> >>>> I confirmed the bad one by removing the piggyback and the failure >>>> returned. Now I need to desolder the bad one without ruining the >>>> board. I may just cut the leads off close to the bad chip, and >>>> solder the replacement to the stumps. (Normally I remove the legs >>>> and install a machine-pin DIP socket). Or just solder the piggyback >>>> and leave it there... thoughts? >>>> >>> Cut the leads close to the body.? Apply a soldering iron to each >>> lead, and pull the lead out with tweezers, >>> simultaneously heating and pulling.? This is very gentle to the >>> board, just doing one at a time.? Then, you can vacuum out the holes >>> and install a new chip or socket. >>> >>> I've done this many times, and never wrecked a board. >>> >>> Jon >>> >> That's how I do it... the vacuuming is the problem. Someday I need to >> get a good vacuum desoldering station. Right now I just have a >> spring-loaded solder sucker (which I can do a pretty decent job with >> on most boards). But this high-density layout (2 traces between DIP >> pads) I'm a bit wary of. >> > Just be gentle, and you should be able to do it.? Also, in some cases, > you might heat from the opposite side from the solder sucker.? That > way, you can keep the soldering iron on the pad until you have > triggered the sucker.? But, yes, the hollow soldering iron with > powered vacuum is amazing the first time you try it.? I got one at an > auction years ago, it is much better than the regular iron and > plunger-sucker. > > Jon The small company I first worked for had a Pace unit. I remember not being impressed with it - frequent clogs, pads lifting, and not getting all the solder out, no matter how we set things. Still beat solder-wick though! I got it done, but pin 16 (which connects directly to the internal-layer ground plane) was a bear. From the feel of it and the heat required, the draftsman didn't bother to make pad reliefs. Anyway it's now socketed, so of course it will never fail again! I also made a small jumper on a 15-pin D-sub to connect Monitor Present L to ground, so that annoying "Monitor Error 9" message stops ;) On to the next project!

3 years, 10 months

Imsai and others in Montgomery, AL

by sales＠elecplus.com

https://www.facebook.com/marketplace/item/960320167759670/ Guy is cleaning out his shed because he is moving. Not affiliated with seller, etc. Cindy Croxton Electronics Plus 1613 Water Street Kerrville, TX 78028 830-370-3239 cell sales at elecplus.com -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

3 years, 10 months

LK201 emulation

by paulkoning＠comcast.net

Gentlepeople, I've been having problems with broken LK201s, so as a workaround I created an adapter that connects to a standard PC USB keyboard and makes it look like an LK201. It's based on an Arduino (specifically, Adafruit Trinket M0, an amazingly tiny yet powerful small microprocessor). It's working at this point, though it needs a few small software tweaks to make it complete. I'm going to turn my breadboard into something slightly more polished. Question to the list: is this something that would be of interest to others? If yes, I can make the design available. Perhaps the PCB layout and parts list. I don't think I want to get into building units for others, though. paul

3 years, 10 months

New subscribers?

by ccth6600＠gmail.com

Are new subscribers to cctalk still accepted? My subscription request was left unanswered. With all the talk about the future of this list I wonder if I came too late. Thanks Tom Hunter

3 years, 10 months

Malfunctioning VT240 - help please

by charlesmorris800＠centurytel.net

> On 06/11/2020 02:29 AM, Mattis Lind via cctalk wrote: > >/If that would be the case I think the system would fail />/quite soon rather than on test 5. A guess is that this is />/a memory problem. / That was a good guess, everyone ;) I got some new 4116's and piggybacked (dry, no solder) two of them atop my suspects at E3 & E4. Didn't fix it. Of course :/ In the meantime I've acquired a nice HP 1630G logic analyzer complete with pods and cables. Setting it up was going to take quite a while since I'm not familiar with this model. So I decided to try a simple brute-force approach before the analyzer. I piggybacked another 4116 onto each soldered-in 4116, one at a time. Actually easy to do since with the leads properly formed, I didn't even have to solder it in place, just turn off the power and move it to the next chip. On the 16th, the last one of course, the terminal booted normally and works again. :) I confirmed the bad one by removing the piggyback and the failure returned. Now I need to desolder the bad one without ruining the board. I may just cut the leads off close to the bad chip, and solder the replacement to the stumps. (Normally I remove the legs and install a machine-pin DIP socket). Or just solder the piggyback and leave it there... thoughts?

3 years, 10 months

Ancient transistor ?computer board (Peter Van Peborgh)

by peter＠vanpeborgh.eu

Guys, I now know it is an early CDC board. IT had C*NT*OLDATA on the reverse - how I missed that must be attributed to old age. (Thanks Doug) Here are shots of the back: https://photos.app.goo.gl/UPozyBB3zp7XYcP79 Any idea what the row of hole opposite the contacts were? Testing points? But then why holes and not short pillars? Some are labelled on both sides. Continuing in hope, peter

3 years, 10 months

Future of cctalk/cctech

by boris＠summitclinic.com

Agree that current mailing list format is best as simple, low bandwidth and can always post links to images or other large files. I still use Eudora as my email client and have text only emails. Seems to perplex a lot of people I deal with when I can't read their emails, but it seems somewhat wastefull to use 1-2 Mb to send a message that only needs 200 bytes at most (once one strips off all zero-information fluff from the email). Run my own mailserver as well so can email myself massive attachments when email is only way of getting data off a remote machine. Images take up a lot of space and are best dealt with via links. I've run my own webserver/ftpserver since 1999 and find that's the easiest way of sharing large files with people. While it's nice having high resolution photos like those that Samsung phones creat, they're in the 3-5 Mb size range. If I need to put a lot of photos on a web page, I'll use the free Photo Studio program (written by John Hawkins) which creates a web page with a series of thumbnails with full image available by clicking on thumbnail and can set size of thumbnail image. Rather old, but works fine for simple web pages where all one wants to do is serve up a set of images. Remember 15 years ago that online documentation was sparse but have found most DEC manuals are online and C64 stuff a lot easier to find than it used to be. Being rather paranoid, I've downloaded manuals for all machines I have and keep a duplicate copy of everything. Not sure how many people are on cctalk/cctech, but keeping everything text only would be best way of minimizing bandwidth for whoever hosts it, Boris Gimbarzevsky >On Fri, Jun 19, 2020 at 3:31 PM Maciej W. Rozycki via cctalk < >cctalk at classiccmp.org> wrote: > > > Sure, there's always `uuencode' when you do need to post that non-text > > piece (which I guess will keep the eyes of Luddites away from it too). > > > >Or an http, https, ftp, or gopher url to somewhere else hosting the image. > >Pat

3 years, 10 months

Someone's confused

by jnc＠mercury.lcs.mit.edu

Love the title on this: https://www.ebay.com/itm/184317705963 eBait auction: "16K Sense Inhibit Board .. VAX 6000, VAX-11/730". Yeah, core on a VAX! And such a deal, a mere US$400! Noel

3 years, 10 months

Fixing an RK8E ....

by bob＠jfcl.com

It appears that my RK8E has a problem - it fails the diskless control test with .R DHRKAE.DG SR= 0000 COMMAND REGISTER ERROR PC:1160 GD:0000 CM:0001 DHRKAE FAILED PC:6726 AC:0000 MQ:7777 FL:0000 WAITING Ok, maybe a bad bit in the command register so I'll check it out. But then it dawns on me - how do you work on this thing? It's three boards connected with "over the top" connectors - you can't use a module extender on it. Worse, the M7105 Major Registers board is the middle one of the stack! Is there some secret to working on this thing? Has anybody fixed one? Any suggestions? I hadn't thought about it before, but the KK8E CPU would have the same problem. Fingers crossed that one never dies... Bob

3 years, 10 months

Hercules SDLC/BSC interfacing project - want 3174-x1R

by mattislind＠gmail.com

Hello! I have been working on interfacing the Hercules emulator with various real terminals for some time. First project was an Alfaskop terminal cluster which I connected using a small STM32 controller handling BSC. Next is an Informer 213, portable 3178/3174 compatible terminal. It it using SDLC. A friend has a 3178 and 3279 which would interesting to work with. A 3174-51R/-61R/-81R/-91R would be very suitable for this. It would be very nice to test my BSC and SDLC code with the real IBM stuff. I have put my project here: https://github.com/MattisLind/alfaskop_emu/tree/master/Utils <https://github.com/MattisLind/alfaskop_emu/tree/master/Utils> Still very much Work In Progress. If anyone has a type 1 3174 that does BSC and SDLC so I could test my stuff I would be very interested. No need for fancy features like TCP/IP and/or token ring. I of course pay shipping. But can throw in various DEC QBUS stuff as a trade. /Mattis

3 years, 10 months

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test-drb June 2020