test-drb March 2019

test-drb@ccmp.vtda.org

136 participants
102 discussions

by charlesmorris800＠centurytel.net

Regarding my earlier request for help repairing an H786 and H7861, it occurred to me that I could instead use a desktop PC power supply, having several in the junkbox. It's even small enough to fit in there once the H786 is removed. So I patched the wiring harness from the PC supply to the screw terminals on the backplane... 5 and 12 volts at the terminals, Fault lights on the RL's went out, but no green light on the KDF-11B. After a look at the schematics, the simple solution was just to pull the power monitor daughter-card from the H786, so the power OK lines (8640 buffer inputs, DC OK and Power OK) are not being pulled down. Green light on, memory test ran, and boots RT-11 from RL02 :) A better fix will be to drive the DCOK and POK lines from the PC supply, which appears to have a "P.G." orange wire (I'm betting "Power Good" but will check it out first). TSX-Plus won't run though, because there's no real-time clock. Looks like a small transformer and a bit of buffer circuitry is needed to generate a 60 Hz TTL pulse. Or a dongle with a 555 or crystal oscillator. I may have a try at fixing the original supply before going to the trouble (including mounting the PC supply in the chassis and jumpering the two ribbon cables together). Speaking of trouble, today I learned that the "Restraining Cable Stud" mentioned in the 11/23 user manual is not just there for decoration. For the first time (ever), the BA-11S chassis overbalanced and fell out of the front of the cabinet. It hit the floor with a crash while yanking all the ribbon cables off (without breaking anything, incredibly, including a near miss to my feet in socks!) Perhaps installing that cable is a good idea ;) -Charles

5 years, 3 months

PDP-8 signed overflow detection - Apollo guidace computer

by jnc＠mercury.lcs.mit.edu

> From: Ben Bfranchuk > Now they seem to have have found a SCRAPPED Apollo guidance > computer and am rebuilding the missing pieces. Wow. What a great site (and that guy has mad skills, everything from repairing old Teletypes, through designing boards, to repairing analog stuff). Just 'wasted' a good chunk of the morning reading back through it; tons of really neat things (including recovery of the very first FORTH, along with a lot of Diablo drive - from the Alto - repairs). As a shortcut, here: http://rescue1130.blogspot.com/2018/11/ is the backstory on the AGC; about 1/3 of the way down, in "Restoring an Apollo Guidance Computer, part V". Noel

5 years, 3 months

IBM 360 Model 50 information?

by jnc＠mercury.lcs.mit.edu

> From: Al Kossow > Decades later, people are still afraid to release them. I tried to get > 2065 ALDs from someone that had them and they wouldn't give them to me. Sounds like it's time to have someone high up at the CHM talk to someone at IBM to get an OK; if you only ask for permission, not for IBM to cough up the info themselves, that might be doable. I'd try and get a blanket OK for anything more than 20 years old, i) that should be long enough that they'd be OK with it, ii) a moving thing like that would mean you wouldn't have to go back again. Noel

5 years, 3 months

Apollo Ethernet EPROM mystery

by aek＠bitsavers.org

Does anyone have a working Apollo 3C505 ISA ethernet board handy to look at? The MAME guys are trying to figure out if the boot prom and the firmware eproms are populated. There is conflicting information on the net. https://jim.rees.org/apollo-archive/photo-gallery/ether-505.jpg shows no boot prom, but I dumped a boot prom from a board a while ago with 68000 code in it, but didn't dump any firmware eproms, which would have been an odd thing to forget to do.

5 years, 3 months

VCF/PNW Exhibit & Trip Report - The Old Calculator Museum

by bygg＠cafax.se

Noel Chiappa wrote: > > It has been in use at STACKEN at least since the beginning of the 80ies > > I was meaning before that; somewhere in Scandanavia, I expect? Eh, not that > important, I guess. >From Finland. Sold used by DEC Sweden to Stacken, for 1 SEK (aound 20 cents at that time). > Noel --Johnny /\_/\ ( *.* ) > ^ <

5 years, 3 months

VCF/PNW Exhibit & Trip Report - The Old Calculator Museum

by jnc＠mercury.lcs.mit.edu

> From: Mattis Lind >> Ah. I wonder where it came from originally? > It has been in use at STACKEN at least since the beginning of the 80ies I was meaning before that; somewhere in Scandanavia, I expect? Eh, not that important, I guess. >> And it's odd (to me, at least) to see TU56's on a KA10. > It is TU55s as far as I can see. Ah, I was confused by an aspect of the pictures on that page which I hadn't noticed before! The fourth picture in that set: https://mobile.twitter.com/LivingComputers/status/1102063746019549184/photo… which is where I saw the TU56's (along with at least one TU55), shows a different machine! I just assumed all four were of the KA, but the last shows them in front of a KI. Although one has to look carefully to notice that, though, as the size, colours, etc are very similar; it thus looks _very_ similar to the KA in the first ones. I'd still love to find out if there are any other KA's left - does anyone know of any? Noel

5 years, 3 months

Looking for Byte Jan 78 missing page

by wrcooke＠wrcooke.net

In the Jan 78 issue of Byte magazine a series of articles titled "The Brains of Men and Machines" (also the issue title on the cover) started. EVERY single scan I can find on the web is missing pages 96 and 97, right in the middle of that article. They all (including archive.org) appear to be the same scan. Does anyone have an electronic copy of those pages or a paper copy they would be willing to scan for me? Thanks, Will "He may look dumb but that's just a disguise."? -- Charlie Daniels "The names of global variables should start with? ? // "? --?https://isocpp.org

5 years, 4 months

VCF/PNW Exhibit & Trip Report - The Old Calculator Museum

by mattislind＠gmail.com

torsdag 28 mars 2019 skrev Noel Chiappa <jnc at mercury.lcs.mit.edu>: > > From: Mattis Lind > > > It is KATIA. Peter Lothbergs collection. > > Ah. I wonder where it came from originally? It has been in use at STACKEN at least since the beginning of the 80ies until maybe mid nineties. STACKEN is the computer club at KTH in Stockholm. https://techworld.idg.se/2.2524/1.454545/the-stacken-story I think that some pictures are from the big computer hall I visited when studying at KTH. But it might be Collosal Cave Computing Center. > That looks like a relatively 'new' one; the older KA10's had black panels. > And it's odd (to me, at least) to see TU56's on a KA10. It is TU55s as far as I can see. > > I wonder how many KA10's are left in the world? I have this vague memory > that > MIT-AI might have gone to Sweden, but I also have a memory that that was > the > plan, but some how it didn't happen? /Mattis > > Noel >

5 years, 4 months

VCF/PNW Exhibit & Trip Report - The Old Calculator Museum

by jnc＠mercury.lcs.mit.edu

> From: Mattis Lind > It is KATIA. Peter Lothbergs collection. Ah. I wonder where it came from originally? That looks like a relatively 'new' one; the older KA10's had black panels. And it's odd (to me, at least) to see TU56's on a KA10. I wonder how many KA10's are left in the world? I have this vague memory that MIT-AI might have gone to Sweden, but I also have a memory that that was the plan, but some how it didn't happen? Noel

5 years, 4 months

VCF/PNW Exhibit & Trip Report - The Old Calculator Museum

by jnc＠mercury.lcs.mit.edu

> From: Rick Bensene > upstairs to the computer room and take some photos of the KA-10 Wow! That's a rara avis indeed; I wasn't sure there were any left. Does anyone know where this one came from? Noel

5 years, 4 months

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test-drb March 2019