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I'm checking out this H7225 "constant voltage conditioner" which belongs to the museum I volunteer at. Does anyone have experience with it? What type of installations would typically use one of these? It works fine, although it makes a fairly obnoxious buzzing sound - is that typical for these...

[EDIT: 11/24, not 11/04] Isn't an 11/24 the simplest Unibus PDP? One hex module for CPU, another for memory. As I recall, the BP is a bit unique, but perhaps can be made from a DD11-DK or similar?? Pete

The disk controller board you have is half of a UDA50: https://gunkies.org/wiki/UDA50_Disk_Controller A UDA50 is probably "essential" in a Unibus system IF you will have SDI drives. Pete

I had a VT103 that I bought in the 80's via the 'Employee Purchase Program'. It cost me over $4K. I still have the Q-bus backplane from it, but nothing else. It has an edge connector for the VT100 board to plug into. Check the 103 print set to be sure, but I think the VT100 module (that does...

Hi, If this is what you need, PM me a mailing address, and I'll send it to you. It's apparently 'NOS'. You might as well take the entire holder - I have nothing else that matches it, and I no longer have any complete DEC machines that might use it. Pete

Hi Lee, Can you post a picture of the type you want? My "fuse holder box" might easily have what you need, but I'm unclear which style... Pete

Those referenced PDFs are very useful for a lot of discrete parts - thanks for pointing that out, I'd never seen it before. Too bad it's from 1970 -- a 1985 version would be really nice... See my earlier post above. The Component Index books list basically EVERY part. For the parts on a...

What happens when you explain this to them. Do they ignore you? Surely they *want* to sell stuff...

On second thought, I'm starting to remember that there WAS a printed part number list. My memory is fuzzy, but it was 3 volumes, paperback, gray/brown color. Each volume was about 1" thick, but one of the volumes was closer to 2" thick. Would have been used by folks in Component Engineering, but...

FWIW, the 50-class (bare PCB) is often clearly marked on a board etch, the 54-class (board assembly) may or may not be marked with a paper sticker. I've never seen a list of those PN's out in the wild. And I don't remember ever seeing a printed version. I would suggest that it was never needed...

Here's the bit fields for the UDA50, as seen on the schematic. The KDA50 designer told me that the UDA and KDA have almost identical fields, so this should be really close to the KDA. 00-11 branch addr 12 CROM parity (odd) 13 JUMP OP 1 14 conditional execute 15 SENSE 16-19...

This is related to the recent thread where somebody was asking about making a PDP11 by using a 2901 bit-slice architecture. The KDA50 is one of several DEC modules that already implements a complete 2901 processor. Since I apparently have too much free time ( :-) ), I wrote code for my...

I don't have any specific examples, but boards like this were intended as a way to get the chip into engineer's hands, so that they might want to use it in a product. Educational institutions would be part of that, because student-engineers graduate and go to work for companies, where they can...

https://manx-docs.org/collections/antonio/dec/MDS-1997-10/cd3/VOL003/0363.PDF Pete

Do you have an SA7x OCP? It will display status/error codes. I worked in the site that made that drive (CXO, Colorado Springs), but I don't have any experience with it... Pete

Ah, good point! I had forgotten about that. I (myself) would never attempt to do a PDP instruction set. But if the microword were decoded, perhaps it be possible to do something simple (like blink an LED) with just a couple of the EPROMs installed. A 'baby steps' way to avoid the tedium of...

My first thought for a "project" was to try and decode the microword fields. Then hand-assemble a few words of code, burn EPROMs, and make the diagnostic LEDs blink. I (myself) wouldn't attempt it without schematics - any significant 'guessing' would take the fun out of it. jplr: Thanks for you...

While on this topic, does anyone here have schematics for the KDA50 controller (M7164)? The print set would be MP-01423. I know I had a hard-copy years ago, but I must have disposed of it... I still have an M7164 module, so it makes me think of project ideas... [Danger, Will Robinson!]...

No, unfortunately... Last I heard, he's still here in town, working for XioTech as Chief Scientist. Pete

Hi again. As for the number of PROMs, I was talking about the UDA50 controller, which has 6X2, the same as the L0107 in the HSC50. Both were developed early on (about 1980-ish). All the later products (starting with RC25, then KDA50, then KDB50) had just 6 chips. The next controller, the KDM70...