test-drb

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101090 discussions

by robertlipe＠gmail.com

Hi, Warren. We've spoken a few times through the decades, but a have a friend with a delightful relic of PC Unix history: the original 286 UNIX port, well before SCO with Xenix. Bela is in Mountain View, CA so he's on the wrong continent for you, but I figured you might know of an appropriate home for this. https://m.facebook.com/story.php?story_fbid=3516115585074301&id=10000027682… Thanks for all you've done to preserve UNIX. RJL

6 years

Unisys MCP (was: Re: UniSys ClearPath OS/2200 Express?)

by sieler＠allegro.com

i> From: Alan Perry <aperry at snowmoose.com> > Why would one get OS/2200 when they can get https://www.unisys.com/offerings/clearpath-forward/clearpath-forward-produc… ? thanks! As an old MCP user/developer (although outside the lab), that's really interesting to me! Note: you have to register to get the software. That's apparently done by clicking on "Downloads". Then you're presented with a registration form. After submitting it, you're told you'll receive an email. Don't hold your breath. It's been 20 minutes, and no email from Unisys :( (And, no email --> no download) Stan

6 years

T-11 evaluation module manual page A-92 added

by aek＠bitsavers.org

fixed version at http://bitsavers.org/pdf/dec/pdp11/t11/EK-DCTEM-UG-001_DCT-EM_Users_Guide_S… name changed to differentiate it from other copies on the web

6 years

Looking for BAD / Faulty core memory for a display piece

by mokuba＠gmail.com

Unrepairable preferred It'll be going into an epoxy resin setup that someone I know is doing for a table, and I really want to get something that still LOOKS OK but is... well, just faulty and won't be restorable to service so we don't destroy any potentially usable hardware. Ideas/suggestions welcome! -- Gary G. Sparkes Jr. KB3HAG

6 years

windows program to read papertape from reader through serial port

by billdegnan＠gmail.com

Hi - I read on teraterm's forum or something like it that teraterm is not really equipped to receive an inbound papertape reader dump into an ascii file. What do those of you who have both windows and a tape reader use? RealTerm? If so, what settings? I have been wresting with this for a while...I am told my DSI NC 2400 needs hardware flow control Thanks BIll

6 years

Fan problem with DEC H7822 power supply in MicroVAX 3100

by cctalk＠beyondthepale.ie

I have a MicroVAX 3100 which has a H7822 power supply. The power supply and the machine itself mostly work (there is a problem with the SCSI interfaces but that's another story) except that the two fans in the power supply don't run. If left on for a long time, the machine gets too hot and a thermal trip operates, shutting it down. The fans are DC 12V 0.2A and if I connect them to +5V or +12V, they work fine and don't draw excessive current so there would seem to be a problem with the section of the power supply which drives the fans. Unfortunately, it's operation is not obvious and the power supply is a pig to work on. It consists of two double sided PCBs connected by short leads and having live parts on both boards making it difficult to get access to both sides of the board where the fan circuit is when the power is on. I don't have an identical working power supply to compare the faulty one to but the fan circuit looks superficially similar to the one in the H7821 which I do have working examples of so that may be a way to proceed. Does anyone have a service manual for the H7822 or H7821 or know how the fan circuit is supposed to work in these power supplies? Regards, Peter Coghlan.

6 years

Anyone out there that can read 7 track / 556 BPI tapes?

by cramcram＠gmail.com

Hi, I bumped into an old friend of mine today. We both talked about a pair of machines we worked on that no longer exist as far as we cant tell. They were both Adage machines and had the same base digital architecture. Their names are Ambilog 200 and AGT-30. The Ambilog was the predecessor to the AGT line. The AGT came in 3 flavors, AGT-10, AGT-30 and AGT-50. The 30 seems to have been the most prevalent. They were 30 bit, one's complement machines. The Ambilog had a beautiful console that used an IO Selectric. It was designed as a 2D vector graphics machine. Here's an image of the Ambilog 200: Ambilog 200 <https://d.lib.ncsu.edu/collections/catalog/ua023_024-001-bx0010-020-004#?c=…> The AGT/30 was a very advanced 3D vector machine. The XYZ signals for the display came from a 4 x 3 "hybrid" matrix multiplier which allowed for 3D imaging with Z axis depth cueing. The matrix multiplier was a 19 in rack of a dozen discrete 15 bit multiplying D to A converters. About once a year it had to be re-calibrated due to long term drift. Here's a link to an image of an AGT-30: Adage AGT-30 <https://www.google.com/url?sa=i&url=http%3A%2F%2Fwhat-when-how.com%2FTutori…> And here is it's 1.5 seconds of fame from the SciFi classic "Dark Star": AGT-30 das Blinkenlights <https://youtu.be/ocse-0bBfo8?t=3152> Anyway, it turns out he has quite a few of the source and backup tapes. Unfortunately they are 7 track 556 BPI. So the question is: is there anyone out there that can assist with either reading these tapes or (better yet) has a 7 track tape head we could buy? Our goal is to preserve this forgotten machine designed at the start of the computer graphics era. Writing a full emulator is our goal. I live in the Bay Area. Maybe those of you with connections to CHM could see if we could read the tapes on the 1401. Or maybe one of you has a 7 track driver in your junk file. All we really would need is the head and we could put it on an existing drive. As a last option, a commercial tape recovery vendor although that is probably too pricey. Thanks, Marc Howard

6 years

Motorola 12Xbug?

by cmhanson＠eschatologist.net

Does anyone know where to find Motorola 120bug or 12Xbug? I have an MVME121 but it has a third party ROM, not the typical Motorola boot ROM. (The 12Xbug manual would be handy too, of course.) -- Chris

6 years

MVME225 documentation

by cmhanson＠eschatologist.net

Does anyone have MVME225 documentation? I have one of these boards now and no docs for how to set the addressing jumpers/switches. -- Chris

6 years

When is a capacitor not JUST a capacitor (i.e., not just a filter or part of a resonant circuit)

by cube1＠charter.net

(And not acting as part of a resonant circuit) Answer: When it is acting like a little delay line. https://www.computercollection.net/index.php/2020/07/18/q-when-is-a-capacit…

6 years

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