July 2018 - vcf-midatlantic

Head align Tape
by Duane Craps 15 Jul '18

15 Jul '18

>>> 7 track or 9 track? The Univacs are pretty old even for "vintage". Head alignment tapes are not track specific. They have one track the width of the tape and are used to adjust time delays to time align the bits coming off the read head when reading the alignment tape. Then a "scratch tape" is used while writing all ones to adjust the write delays while looking at the read amps. We used the same alignment tape for 7 and 9 track units. Duane On 6/17/2017 11:40 AM, Dave McGuire via vcf-midatlantic wrote: > 7 track or 9 track? The Univacs are pretty old even for "vintage". On 6/17/2017 11:40 AM, Dave McGuire via vcf-midatlantic wrote: > On 06/17/2017 11:37 AM, Herb Johnson via vcf-midatlantic wrote: >>> UNIVAC 1540 Magnetic Tape Unit...I wonder if anyone has a 800 BPI, >>> NRZ Master Head Alignment Tape (skew tape) to donate to VCF. >> 7 track or 9 track? The Univacs are pretty old even for "vintage". >> >> Also, as Dave McGuire noted, a lightly-used tape from a known-good drive >> will be useful. In the floppy-disk world, I use several diskettes each >> from a known good drive to validate "alignment". > That wasn't me. But yes, that can be useful for rough validation. > >> Seems to me, there's likely several boxes of mag-tapes in the inventory. > Yes, I brought a few boxes several years ago. > > -Dave > v

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OT: Sussex NJ Hamfest Sunday
by Kelly Leavitt 13 Jul '18

13 Jul '18

August 15th. I know a lot of you folks like to go to this one. Stop by the kitchen and say hi. http://www.scarcnj.org/hamfest.html NJ Staite Fair grounds. 37 Plains Rd, Augusta, NJ Directions: https://njstatefair.org/html/maps.cfm Kelly

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early (original?) Dartmouth BASIC documentation
by Glenn Roberts 12 Jul '18

12 Jul '18

I've been helping a friend clean out some closets after her husband died - he was like many of us and had a lot of history in computing. While he had already gotten rid of early hardware I did find some interesting artifacts in his bookshelves. One book that caught my attention is "a manual for BASIC" by John Kemeny and Thomas Kurtz (Dartmouth). It is copyrighted 1965 by Dartmouth and appears to be the original manual for Dartmouth's BASIC. The preface acknowledges an NSF grant for funding the language development. Includes diagram/instructions for using the Model 33 teletype and paper tape! Anyway, just thought I'd share with this group. I imagine there aren't too many copies of this left around. Google search turned up some hits but I didn't see any scans of the book. It's pretty short (63 pp.) Nice keepsake from the earliest days of BASIC... - Glenn

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Re: [vcf-midatlantic] Known-good IBM joystick?
by Bill Degnan 11 Jul '18

11 Jul '18

Bob/All, In IBM systems one typically needs the drivers, controller card, and joystick to all be designed to work together. Also, the software often expects one of a few model joystick to be available. So, in Evan's case he needs to look at the software and documentation of the program that will use the joystick to see what kind of joystick it's looking for. It may be that the original IBM PC "Game Control Adapter" is an option, in which case you'd need something compatible with that. May be easy and you can get away with a serial port joystick. And so on. From there, find something compatible, install the drivers into autoexec.bat and config.sys and go from there. Newer machines often pair a soundcard like SoundBlaster with a Microsoft joystick. Evan may have working joysticks that "don't work" because the drivers are not yet loaded. Bill On Tue, Jul 10, 2018 at 8:38 AM Bob Aviles via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > Hi, > I have an IBM joystick, look at the picture and tell me if it works on > your systems. > > Bobby On Tuesday, July 10, 2018, 1:20:45 AM EDT, Evan Koblentz via > vcf-midatlantic <vcf-midatlantic(a)lists.vcfed.org> wrote: > > I'm having issues with the VCF supply of Kraft joysticks, and there is > no time to fix them before HOPE. Does anyone have a tested and > fully-working / known-good IBM (or other non-Kraft) joystick which I > could borrow? I need it by Friday in order to test it at the museum this > weekend. Dean said he may have one, but in case he doesn't.... > > My backup plan is to program for keyboard control instead of joystick > control, but that's not nearly as much fun. > >

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2u blanking panel?
by Evan Koblentz 11 Jul '18

11 Jul '18

Before I buy one: does anyone have a solid (non-vented) 2u blanking panel? We need one to complete our network rack.

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Re: Known-good IBM joystick? (Evan Koblentz)
by mike willegal 11 Jul '18

11 Jul '18

A quick note on reading the Joystick ports on an Apple II. The circuit uses a RC timer to discharge a capacitor to measure the resistance of the potentiometer (resistor). If you do multiple PDL reads back to back, you may get a faulty reading the second time. This is because the capacitor needs time to recharge before the second read. It's best to put some other code in between the paddle reads in order to give the capacitor time to fully charge. regards, Mike Willegal

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Re: [vcf-midatlantic] Museum report: terminals (Ethan Dicks) (Michael Thompson)
by Earl Baugh 11 Jul '18

11 Jul '18

> > We had a VT14 at the RICM that had cataracts. We used dental picks to > remove the silicone holding the metal mounting band to the CRT. We planned > on using a hot wire to cut the PVA, but when we started picking at the > edges of the PVA we found that very little PVA was adhered to both the CRT > and the shield. Cleaning up the PVA was tedious, but not difficult. > > We were concerned about putting a CRT without the PVA in a public place in > the museum. We had images of a young visitor breaking the CRT and glass > flying everywhere. > > We bought some 0.093" thick Lexan at Home Depot, waited for my wife to go > shopping, and put the Lexan on top of the glass shield in the oven. When > the temperature hit 325F the Lexan conformed to the glass shield. We > trimmed the Lexan to the same size as the glass shield, and use silicone to > hold everything together. This is probably a lot safer than the original > PVA and won't degrade. > > There are pictures and a description of what we did here: > http://www.ricomputermuseum.org/Home/equipment/dec-pdp-12/ > dec-pdp-12-restoration > > I love that you clearly pointed out the most important step in this repair --- waited for my wife to go shopping --- :-) Earl

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Workshop report
by Evan Koblentz 10 Jul '18

10 Jul '18

Various notes about the workshop follow... - Jeff G. is almost done making one good/working IMSAI from the two parts machines that were formerly Roger Amidon's. When it is totally done, then we will make a video to show it is fully working and we'll sell the computer on eBay. This is to maximize its value because the proceeds will be donated to Roger's family. Jeff had some (remote) help from Herb (documentation) and Glitch (ZPU board). - Ian repaired VCF's PET 2001 (replaced the magic smoke!) and IBM 5150 (disconnected a faulty memory expansion board that was causing trouble). He and Dean also repaired the modern(ish) PC that we're going to use as a BBS server -- I couldn't get any video from it; turns out the CF card adapter that Dean installed as an SSD (8GB was fine because it's only running DOS) was being pushed down by another component and bending the motherboard! We improved the other component by cutting out an infringing piece of metal bracket. :) He also helped Tony with a CRT issue and helped Jeff B. with one of Jeff's 64s. - We have a new member, Marco (15 yrs. old), who brought in his iMac. It needed a lot of work + CRT repair. Ian helped him and used parts from one of our spares. - Jason Perkins brought in a very nice/modern rack console for us and showed me how to install it. - I ordered the wrong patch panel. Got the correct one coming soon. - Mike Lowen worked on VCF's Zorba portable computer. It needs more TLC than he could do at the workshop, so I let him take it home for further repair. Mike got his own HP-3000 working! Exciting stuff. - Bill Drom. got the UNIVAC running more reliably and taught me, Tony, and Dean how to turn it on + do a quick 1-minute demonstration (it tests all of the CPU's 102 instructions and tests 40K of core memory). I will show other docents. - Bill and Mike helped me troubleshoot + repair the Compaq Portable III that I need working for my HOPE lecture. Lego card wasn't talking to the interface box. Turns out the problem was a dirty connector between the computer and its "backpack" card expansion module. Deoxit solved that. - Dean helped me learn how to use the STICK and STRIG (presumbably derived from "Stick Trigger") commands in Compaq's flavor of IBM/MS BASIC. Different from the Applesoft that I know, where stick control is PDL(0)/PDL(1) and reading the buttons is PEEK(49249) and PEEK(49250). - I'm not sure what else Jason, Jeff J., Tony, and Ian worked on.

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Re: [vcf-midatlantic] Known-good IBM joystick?
by Evan Koblentz 10 Jul '18

10 Jul '18

No. Everything is great with the Apple branded joystick connected to our Laser 128. Where I'm having trouble is with a dual Apple/IBM stick connected to a Compaq luggable. Anyway it sounds like Tony is bringing one into the museum later this week, which I can test on Saturday. On Tue, Jul 10, 2018, 12:42 PM Bob Aviles via vcf-midatlantic < vcf-midatlantic(a)lists.vcfed.org> wrote: > Question, what you need is an Apple joystick? because I have some. > Bobby > On Tuesday, July 10, 2018, 12:40:07 PM EDT, Evan Koblentz via > vcf-midatlantic <vcf-midatlantic(a)lists.vcfed.org> wrote: > > >> The BASICs are 100% compatible? You just had one change and it works > on > the IBM? > > Pretty much! I also changed the joystick button code. Applesoft uses a PEEK > to check for button presses, BASICA uses the STRIG command. Everything else > is the same. > > On Tue, Jul 10, 2018, 12:32 PM Bill Degnan via vcf-midatlantic < > vcf-midatlantic(a)lists.vcfed.org> wrote: > > > On Tue, Jul 10, 2018 at 11:53 AM Evan Koblentz via vcf-midatlantic < > > vcf-midatlantic(a)lists.vcfed.org> wrote: > > > > > I'm using a Compaq Portable III (286). I forgot the card brand but I > > > vaguely recall it might also be Kraft. I'm programming in the BASICA > from > > > the correct Compaq-branded boot disk. I use the STICK command; not > > > PEEK/POKE. > > > > > > I can test the same joystick against the Apple side tomorrow. > > > > > > In a test program, I was only getting a range of about 5 to 195, vs. > > 0-255. > > > > > > To "port" the code from Apple to IBM platform, I replaced the Applesoft > > > PDL(0) and PDL(1) commands with STICK. > > > > > > The way my code works is, when I move the stick beyond a neutral range > > > (say, within 75 of either end), then it turns on the robot motors on > the > > > correct directions. > > > > > > The logic is fine: works with the Apple joystick on the Laser 128, and > > as I > > > said I'll test that again with the Kraft tomorrow on the Laser. > > > > > > But when I tried it on the Compaq, only two of the directions work > > > correctly. It was something like left and forward; I forget exactly. > One > > > other direction turns on the wrong bits (1 and 4, same as its opposite > > > direction, rather than 2 and 3 which it should be), even though I'm a > > > million percent certain the code is right. Another direction works > (bits > > 2 > > > and 4) if I move the stick to its extreme edge, but while en route it > > turns > > > on bit 3 for a second. That makes no sense! That's why I think the > stick > > > might be funky or somehow misadjusted even if it does work on the Apple > > > side. > > > > > > > > > > > The BASICs are 100% compatible? You just had one change and it works on > > the IBM? > > b > > > >

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Re: [vcf-midatlantic] Museum report: terminals (Ethan Dicks)
by Michael Thompson 10 Jul '18

10 Jul '18

> From: Ethan Dicks <ethan.dicks(a)gmail.com> > Subject: Re: [vcf-midatlantic] Museum report: terminals > On Mon, Jul 9, 2018 at 12:27 PM, Jonathan Gevaryahu via > vcf-midatlantic <vcf-midatlantic(a)lists.vcfed.org> wrote: > > On 7/9/2018 11:39 AM, Herb Johnson via vcf-midatlantic wrote: > >> > >> I saw many "moldy" CRT's - that's when the front of the CRT has a > >> transparent cover that's separating from the glass. Repair means > replacing > >> the CRT, which can take most of an hour depending. > > AFAIK, it's bubbles in the PVA layer between the face of the CRT and > the implosion protection screen. > > > These CRT tubes don't have to be replaced, the CRTs can be very carefully > > heatgunned to remove the front protective glass cover and scrape out the > > 'cataract' goo. I think Ian has done it to a few of them already? > > I've done it with a VT220. You can use a heat gun or a hot wire to > cut the PVA to free the shield from the tube, then it's all cleanup. > You do need to re-install the shield because otherwise the CRT clamps > don't fit really well and the tube slides around. I used dots of a > thick (1mm?) silicone "tape" on the corners and it worked well. Just > a small airgap in front of the face of the tube instead of a layer of > what is supposed to be optically clear PVA. > > -ethan > We had a VT14 at the RICM that had cataracts. We used dental picks to remove the silicone holding the metal mounting band to the CRT. We planned on using a hot wire to cut the PVA, but when we started picking at the edges of the PVA we found that very little PVA was adhered to both the CRT and the shield. Cleaning up the PVA was tedious, but not difficult. We were concerned about putting a CRT without the PVA in a public place in the museum. We had images of a young visitor breaking the CRT and glass flying everywhere. We bought some 0.093" thick Lexan at Home Depot, waited for my wife to go shopping, and put the Lexan on top of the glass shield in the oven. When the temperature hit 325F the Lexan conformed to the glass shield. We trimmed the Lexan to the same size as the glass shield, and use silicone to hold everything together. This is probably a lot safer than the original PVA and won't degrade. There are pictures and a description of what we did here: http://www.ricomputermuseum.org/Home/equipment/dec-pdp-12/dec-pdp-12-restor… -- Michael Thompson

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