test-drb April 2019

test-drb@ccmp.vtda.org

134 participants
129 discussions

by jnc＠mercury.lcs.mit.edu

> From: Nigel Williams >> it's the same as all the other PDP-11 etc logo panels,... > when you say "same", as in the same text as well? Sorry, I should have been more explicit. 'Same physical shape' is what I meant; just different stuff painted on the insert. > thanks for the confirmation. Sure, glad to help. Noel

5 years, 8 months

DEC PDP-11/70 cabinet setup

by jnc＠mercury.lcs.mit.edu

> From: Nigel Williams > I'm wondering if on a real 11/70 there is a 5mm gap between the > masthead and the rack blanking panel below it? If by "masthead" you mean the thing DEC calls a "Logo Panel" (see 11/70 Engineering Drawings, 'Unit Assembly', pg 1 of 5), it's the same as all the other PDP-11 etc logo panels, the -11/70 just has an inlay (thin metal sheet) which is painted differently. And yes, there's a 5mm gap between the top of the top 10-1/2" blank panel, and the bottom edge of the logo panel. Noel

5 years, 8 months

Telex 20 Meg 10 platter very heavy monster drive needed drop line off list..r

by couryhouse＠aol.com

Subject: Telex 20 Meg 10 platter ?very heavy monster drive needed drop line off list.. Telex 20 Meg 10 platter ?very heavy monster drive needed drop line off list thanks Ed# ---hope this works and see ds from phone ok... thx-------

5 years, 8 months

Rgb intensity line

by billdegnan＠gmail.com

I am fashioning an RGB cable from parts. The computer (LNW80) does not send an "intensity" signal, it is only a 6pin rgb. The magnavox rgb 80 display that I wish to use to receive has a pin for an intensity signal. Other than "intensity" the rgb signals can be matched up. Question...what happens when a computer does not send an intensity signal to a display that has this input? I will find out soon enough but I am curious to ask before I begin should anyone have a suggestion. Do I need to add a resistor off of ground or something to fix it to something? Bill

5 years, 8 months

DEC PDP-11/70 cabinet setup

by nw＠retrocomputingtasmania.com

I'm hoping to (partially) recreate an 11/70 setup, at least as close as I can get with what I have on hand (see the first pic in this gallery that shows the 11/70 advert): https://imgur.com/a/pvgUVmg I don't have the right masthead but I'm wondering if on a real 11/70 there is a 5mm gap between the masthead and the rack blanking panel below it? I can't see with these pieces a way to close the gap, but I'm curious as to whether the real thing also has the gap? thanks.

5 years, 8 months

Plane of core memory

by jnc＠mercury.lcs.mit.edu

> From: Curious Marc > I believe 3 wire memory was first introduced by IBM in their 360 > systems ... They would almost certainly have patented their way to do it Correct (and your knowledge and memory is good)! Motivated by this clue, I looked in: Emerson W. Pugh, "Memories That Shaped an Industry" MIT Press, Cambridge, 1984 where the description of the invention of 3-wire core can be found on pg. 231; it was invented by a group of engineers, based on a similar idea used in Stretch. There is indeed a patent, No. 3,381,282, with six names on it. IBM must have licensed it, but there is nothing on that. I can highly recommend that book; it's in the same league as the later two books on early IBM computers from MIT Press on which he was a co-author. Noel PS: There was recent discussion here of the 8000 series; there are some details on that on pp. 189-191.

5 years, 8 months

Care and feeding of true barn-find systems

by aperry＠snowmoose.com

Yesterday I rescued a Sun 3/260 that had been sitting in an open barn for years. It had been "running when parked" a dozen years ago.? It seems to have been covered by a tarp, but otherwise unprotected. All things considered, it doesn't look that bad but it is pretty rough. Any pointers on things that I should and shouldn't do as I start trying to bring it back to life? alan

5 years, 8 months

MSCP Conformance tests?

by derschjo＠gmail.com

I'm working on implementing an MSCP controller on top of Joerg Hoppe's Unibone and I'm making pretty good progress -- RT-11 works and I'm working on getting 2.11bsd to boot from it in an 11/84 (it works well enough to load "boot" which then loads the kernel, then things fall over). However, given the complexity of the protocol I'd like to be able to test it against something official rather than going from OS to OS and hammering out issues as I find them. DEC's UDA50 diagnostics assume an actual UDA50 (and expect specific behaviors like onboard diagnostics, etc.) and I don't really want to emulate a UDA50 -- I just want to implement a generic MSCP controller properly. I'm assuming the answer is "no" but did DEC ever provide actual MSCP conformance tests (for PDP-11 or VAX) to allow third parties to test their implementations? Thanks as always, Josh

5 years, 8 months

Plane of core memory

by ullbeking＠andrewnesbit.org

Hello all, I have been wanting to acquire a plane of magnetic core memory as a piece of computing history. My partner actually thinks they look very beautiful and says we should frame it, if we ever find a plane. At the time I was thinking about memory from the S/360. But in retrospect, this is not necessary. It would, however, be nice to know what computer a prospective purchase likely came from. It adds to the meaning. One of my online friends just pointed this to me, which I am considering purchasing: https://www.ebay.com/itm/264262833353 There is no indication of what sort of computer it came from. However I have been told to check the bus connector. Does anybody here have any ideas? For example, what is it? Or, if you don't know, could you point me in the right direction so I can do the research myself? Thanks!! Kind regards, Andrew -- OpenPGP key: EB28 0338 28B7 19DA DAB0 B193 D21D 996E 883B E5B9

5 years, 8 months

Control Console, but not PDP-10

by pbirkel＠gmail.com

The PDP-10 Control Console sold for $3,650.00. Amazing! Now consider a DSKY. Currently at $27,500.00. Auction estimate: $60,000+ Great provenance! ?The DSKY that saved Apollo 14.? https://www.rrauction.com/bidtracker_detail.cfm?IN=5222 ?Apollo 14 LM Simulator Computer Display and Keyboard (DSKY) from MIT Instrumentation Laboratory? Historically significant Apollo Guidance Computer Display and Keyboard (DSKY) unit from the MIT Instrumentation Laboratory, used by Don Eyles and Sam Drake to verify the software patch needed to avoid an abort during the Apollo 14 lunar landing sequence. The data entry and display device measures 8? x 8? x 6.5?, and has 19 keys and an electroluminescent digital display. The back of the unit retains its metal NASA parts tag which reads, ?Apollo G & N System, AGC DSKY Assy, Part No. 2003985-041, Serial No. RAY 26, NAS 9-497, Designed by M.I.T. Instrumentation Lab, Mfg. by Raytheon Co., " with yellow inspection stamps above. In fine condition. Accompanied by a detailed letter of provenance from the present owner, who was employed at the MIT Instrumentation Laboratory to design, build, and maintain the CM and LM cockpit simulators. He retained the DSKY in 1978 when the LM cockpit simulator was dismantled and discarded. The DSKY was the astronaut's interface to the Apollo Guidance Computer developed by MIT, and was critical to every aspect of the mission. Each program had a two-digit code and commands were entered as two-digit numbers in a verb-noun sequence. The device permitted the astronauts to collect and provide flight information necessary for the precise landings on the moon. It was the DSKY that provided the astronauts with critical burn times for engine firings, course corrections, trajectories, and other key calculations vital in getting a crew to and from the moon. The DSKY also reported the program alarm moments before the LM touched down on the lunar surface to land. During Apollo 14, a loose ball of solder floating inside the abort switch of the LM Antares caused an intermittent short circuit, threatening to accidentally activate the switch and rocket the module back into orbit during its landing sequence. In order to prevent that scenario, MIT computer programmer Don Eyles, a developer of the AGC's source code, was asked to hack his own software to find a workaround. This represented the most dramatic moment for MIT's programmers throughout the entire Apollo program, as they had just three to four hours to work out a fix, test it, and relay it to the astronauts in time for Powered Descent Initiation (PDI). Eyles accomplished his task in just two hours, developing a 26-command sequence to be entered into the DSKY that reprogrammed the AGC to ignore the abort button. The codes were relayed to Alan Shepard and Edgar Mitchell with ten minutes to spare, and the LM Antares successfully touched down on the lunar surface at 09:18:11 UTC on February 5, 1971. As the MIT DSKY used to verify the code that saved the Apollo 14 mission, this is an exceptionally important piece of space history. -----

5 years, 8 months

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test-drb April 2019