September 2019 - vcf-midatlantic

Re: [vcf-midatlantic] Museum report - 12/16/18
by Douglas Crawford 04 Jul '20

04 Jul '20

Again? This isn't getting through. On 12/17/2018 12:28 PM, Douglas Crawford wrote: > Great day at the museum. Visitor flow was non stop in the afternoon. > I am grateful for the assistance of Chris and Tony, with their help we > cycled > through the visitors and gave everyone good attention. > Its fun to docent in teams! > > The museum looked sharp and with Tony's help we had most everything > running that is > demo-able.

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Re: [vcf-midatlantic] much ado about chording keyboards
by Eric Rangell 29 Nov '19

29 Nov '19

Thanks Jeff. To give context to this discussion, I built a chording keyboard for my Replica 1 and Apple 2+ by interfacing an Arduino to the keyboard socket and using 5 arcade momentary switches from Micro Center. I coded it so that my fingers chord a hex nibble and the thumb strobes it into the Arduino, and the LED shows whether you are chording the high nibble or low nibble. It is possible to recode it for other chording mechanisms and add switches to choose a mode. Eric

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Another great repair workshop
by Herb Johnson 30 Sep '19

30 Sep '19

http://www.retrotechnology.com/restore/vcfrepair_sep19.html I was going to post about my PDP-8/A repairs at the recent workshop; the linked WEb page has details. When I read Evan's post about his LEGO Logo Robo go-go work, I added some photos and links about that, to my Web page. I looked with effort on the Web for "da schematic" for the motor controller, the thing that was "jumpered" in posted discussion. I was surprised to NOT find it. There's info on the Apple II interface card already, as discussed. Odd someone with skills, hasn't drawn this already. There's the usual reasons, mostly like these things are already available for tens of dollars used. Ah - this Web page is informative: http://lukazi.blogspot.com/2014/07/lego-legos-first-programmable-product.ht… Regards, Herb "copper trace" Johnson -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT retrotechnology DOT info

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Re: [vcf-midatlantic] A little electronics hack
by Evan Koblentz 30 Sep '19

30 Sep '19

Big squiggly area in the center of the second (bottom) image. On Mon, Sep 30, 2019, 1:48 PM Mark Whittington <markwhi(a)gmail.com> wrote: > > https://4.bp.blogspot.com/-DGOlTkGXj_Q/U8-T2uBG5iI/AAAAAAAAATY/7ra6gVkSKg8/… > > > https://4.bp.blogspot.com/-6RLSsFHgMgY/U8-TzfBRxOI/AAAAAAAAATQ/NeiKlqHPevs/… > > Out of curiosity (and assuming I've found the right board images), do you > happen to know where the circuit that Neville identified as faulty is on > these images? Also, I've found a couple of these units for sale in the US > for ~$85 and in the UK for ~$50 that might be useful for backup or reverse > engineering purposes. > > Cheers, > > -Mark > > On Mon, Sep 30, 2019 at 12:57 PM Evan Koblentz <evan(a)vcfed.org> wrote: > >> >> Looks like someone on this list has already done the legwork on this >> as of 2016... https://www.glitchwrks.com/2016/09/12/lego-logo-interface >> <https://www.glitchwrks.com/2016/09/12/lego-logo-interface> >> >> No - that's the card for connecting the computer to the interface box. >> That schematic already existed and we didn't have the card, so Jonathan >> (Glitch) built one for us. That is what you see documented. In the current >> thread I am referring to the interface box itself. There is more info on my >> personal website at http://www.mindsbeforethestorm.com/8bit_hardware.php. >> >> >> >> On Mon, Sep 30, 2019, 11:16 AM Mark Whittington <markwhi(a)gmail.com> >> wrote: >> >>> Looks like someone on this list has already done the legwork on this as >>> of 2016... >>> >>> https://www.glitchwrks.com/2016/09/12/lego-logo-interface >>> >>> On Mon, Sep 30, 2019 at 9:13 AM Evan Koblentz via vcf-midatlantic < >>> vcf-midatlantic(a)lists.vcfed.org> wrote: >>> >>>> >> If you're interested in investigating further if you point us to >>>> schematics we can give suggestions. >>>> >>>> I am giving the box to Neville in early November (don't want to risk it >>>> not >>>> working before the Brickfair NJ event the first weekend of that month). >>>> He >>>> agreed to my request to make a schematic of it. >>>> >>>> The next step will be to have someone else take his schematic, build >>>> one, >>>> and send it back to me for testing. That'll prove that the box can in >>>> fact >>>> be built from just the plans. After that I'll post it on my website. >>>> >>>> A possible third stage would be to make modern improvements, if any >>>> ideas >>>> stand out. >>>> >>>> I'm only interested in the function, not in replicating the physical >>>> case. >>>> But what I would avoid is replacing the vintage computer with a >>>> microcontroller. I'm all for a better interface but strictly against >>>> some >>>> non-vintage computer experience. >>>> >>>> >>>> >>>> >>>> On Mon, Sep 30, 2019, 8:43 AM David Gesswein via vcf-midatlantic < >>>> vcf-midatlantic(a)lists.vcfed.org> wrote: >>>> >>>> > > >> It's called a 'crowbar' circuit. Prevents things from burning >>>> up. >>>> > > >>>> > >>>> > What I normally called a crowbar circuit is the overvoltage protection >>>> > where it intentionally shorts the output of the power supply. This >>>> sounds >>>> > more like over current protection. >>>> > >>>> > > What are common reasons why those stop working? Neville and I >>>> didn't see >>>> > > any obvious signs of damage to it. >>>> > > >>>> > Either component value shift or failed component. You indicated that >>>> it is >>>> > driving the motors better than it ever has. It may also be your motors >>>> > are a heavier load than it was intended to drive. >>>> > >>>> > If you're interested in investigating further if you point us to >>>> schematics >>>> > we can give suggestions. >>>> > >>>> > >>>> > > On Sun, Sep 29, 2019, 1:56 PM Mike Loewen < >>>> mloewen(a)cpumagic.scol.pa.us> >>>> > > wrote: >>>> > > >>>> > > > On Sun, 29 Sep 2019, Evan Koblentz via vcf-midatlantic wrote: >>>> > > > >>>> > > > > Neville noticed something that I wouldn't have. The circuitry >>>> > contains a >>>> > > > > safety mechanism to shut off all power if the current jumps too >>>> high, >>>> > > > such >>>> > > > > as a kid inserting a paper clip. There's probably a technical >>>> name >>>> > for >>>> > > > that >>>> > > > > but I do not know it. Anyway, for unknown reasons this circuit >>>> was >>>> > > > kicking >>>> > > > > in! He jumped it with an equal-length wire. :) >>>> > > > >>>> > > > It's called a 'crowbar' circuit. Prevents things from >>>> burning up. >>>> > > > >>>> > > > >>>> > > > Mike Loewen >>>> mloewen(a)cpumagic.scol.pa.us >>>> > > > Old Technology >>>> > http://q7.neurotica.com/Oldtech/ >>>> > > > >>>> > >>>> >>>

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A little electronics hack
by Evan Koblentz 30 Sep '19

30 Sep '19

Yesterday at the workshop I took out the Laser 128 and circa-1987 Lego electronic parts. They'd been packed away since Maker Faire last year. My new robot barely worked, despite being almost identical to the old robot and running the same software. I found a loose wire connector which Ian fixed. Still had a lot of problems. Neville (a retired EE who first joined the old MARCH group in the mid-2000s and recently came back) started testing things with a meter and scope. He figured out that some of the interface box outputs were only producing half their usual power. We opened the box (a couple of years ago I swapped its plastic rivets for screws). Nothing seemed wrong. It was clean and all of the capacitors looked good for 30+ years old. Neville noticed something that I wouldn't have. The circuitry contains a safety mechanism to shut off all power if the current jumps too high, such as a kid inserting a paper clip. There's probably a technical name for that but I do not know it. Anyway, for unknown reasons this circuit was kicking in! He jumped it with an equal-length wire. :) We tried the robot again. What a difference! Even before it stopped working last year, the motors always seemed kind of weak. I just assumed that was normal because I never knew it any other way. Now I see what normal is supposed to be. The motors run MUCH stronger! It's an amazing improvement. Neville also resoldered a loose LED connector and one suspect cold joint. So I'm a happy camper. The electronics for this set are running better than ever, which means I can focus on the Lego side and the software. I'm giving a big presentation about all of this Lego stuff on Friday, Nov. 1 at Brickfair NJ and then exhibiting it there Saturday and Sunday. Now I do not have to worry so much about the demo aspect failing.

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much ado about chording keyboards
by Jeffrey Jonas 30 Sep '19

30 Sep '19

Here are my chording keyboard references: Start with Wiki: https://en.wikipedia.org/wiki/Chorded_keyboard Douglas Engelbart's chording keyboard looked like piano keys: https://en.wikipedia.org/wiki/The_Mother_of_All_Demos https://www.youtube.com/watch?v=yJDv-zdhzMY "The Mother of All Demos is a name given retrospectively to Douglas Engelbart's December 9, 1968, demonstration of experimental computer technologies that are now commonplace. The live demonstration featured the introduction of the computer mouse, video conferencing, teleconferencing, hypertext, word processing, hypermedia, object addressing and dynamic file linking, bootstrapping, and a collaborative real-time editor." Here's a product with a chording keyboard: https://en.m.wikipedia.org/wiki/Microwriter The Microwriter is a hand-held portable word-processor with a chording keyboard. First demonstrated in 1978, it was invented by UK-based, US-born film director Cy Endfield ... Take a chording keyboard and wrap it around a stick or put it on a small hand-held remote and you have a keyer https://en.wikipedia.org/wiki/Keyer or a "Twiddler", intended for wearable computers: https://twiddler.tekgear.com/ The Twiddler has been "reinvented" as a cordless motion sensor wearable https://www.tapwithus.com/ as discussed here: https://news.ycombinator.com/item?id=17557593 Everything old is new again! -- jeff jonas

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Re: [vcf-midatlantic] Another great repair workshop
by Matt Patoray 30 Sep '19

30 Sep '19

Nice work Tony, Sadly the issue with so many of the Next mono megapixel displays is that the tubes are just low emissions. Since the monitors were powered on and running as long as the machines were powered on. This was not as much of an issue with the Philips and Hitachi color monitors as they were not powered form the CPU and had a power switch and could be turned off. You can boost the screen voltage to try and compensate for that, but it is just a temporary fix. Once tubes get to a point of real low emissions even the screen voltage boost will not help, and then you just end up with a cloudy out of focus mess. Sometimes you can try a rejuvenation of the tube with a CRT tester like the Sencore CR-70 or the Sencore CR-7000 (if you have deep pockets). it is not recommended to use B&K CRT testers for their restore function as it is rather harsh and sometimes can blow the cathode apart rendering the tube useless. As of right now, there is no company that is rebuilding CRT's (but the effort to start rebuilding down in Columbus Ohio at the Early Television Museum is moving forward). So that may be an option in the next few years. On Mon, Sep 30, 2019 at 8:05 AM Tony Bogan via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > > > The two museum NeXT printers and two Megapixel displays are now tagged > with their working state. One monitor just required a little manual > adjustment and focus and is now a viable replacement for the one on display > if it’s ever needed or can be used for one of the three NeXTstations VCF > has if we ever display them. Both printers need work, but replacement toner > cartridges are available (They use HP laserjet II or equivalent cartridges) > and intake rollers can be had as well. I’ve never done it but know it’s > been done before. > > One monitor is working but needs some attention from the Monitor Whisperer > (hi Ian!) to get the image bright enough again to be useable. I spoke with > Ian and Connor at the workshop and we talked about maybe doing a NeXTfest > at a future workshop to get everything working (or at least starting the > process) plus bringing any of our own NeXT machines to work on as well. > > > Tony > -- Matt Patoray Owner, MSP Productions KD8AMG

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Another great repair workshop
by Jeffrey Brace 30 Sep '19

30 Sep '19

Many got things fixed, a few are still working on some. Bill and Duane did some more work on the Univac. They will report on this in a few days as they are extending their repairs another two days. Ian fixed the museum's Amiga monitor and Apple 2 monitor. We had a nice BBQ Saturday night. How about others share what they worked on? The next repair workshop is November 9 & 10 and it will be in the CDL (formerly IXR) building. -- ========================================= Jeff Brace Vice President Vintage Computer Federation

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RIP Adam Rosen
by Evan Koblentz 29 Sep '19

29 Sep '19

Adam Rosen, known for his Vintage Mac Museum website, died at just 53. He exhibited at VCF East a couple of times. Really nice guy. I was sad to read this article today. https://www.cultofmac.com/655174/adam-rosen-vintage-mac-museum

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Next Repair Workshop 11/9 & 11/10
by Jeffrey Brace 29 Sep '19

29 Sep '19

By popular demand the next VCF repair workshop will be ... Nov 9 & 10 This time it will not be in the usual spot: 9032A (not available due to holiday model train show setup. It will be in 9059 which is CDL (Computer Deconstruction Lab: The hackerspace by the entrance). Here is the signup sheet: < https://docs.google.com/spreadsheets/d/1Le5_EtutRBgnOc9_4gLxJb7CGGEpIuTQWjZ… > -- ========================================= Jeff Brace Vice President Vintage Computer Federation

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