Petey P. TwelveJun 15, 2025
My student, Zach, got the famous Whetstone floating-point benchmark running in FORTRAN IV on our PDP-12 (results had never been recorded for a '12 without an FPP). He also implemented the Dhrystone integer benchmark in PDP-8 assembly, which (as far as we know) has never been done before. You can read more about it here, and if you have a PDP-8 compatible machine (with or without EAE), you should be able to run his code to benchmark your system! Way to go, Zach! https://forum.vcfed.org/index.php?threads/pdp-8-and-pdp-12-and-dhrystone-and-whetstone.1253367/ #pdp12 #pdp #retrocomputing #umdpdp12 #pdp8
PDP-8 (and PDP-12, and....) Dhrystone and Whetstone

Hello all! As some of you may already know, I'm currently a student at the University of Minnesota Duluth working with @pahp on our PDP-12 minicomputer. As some may have also already seen over in the PDP-12 #435 thread, I've been working on benchmarking our PDP-12 for the past few months for a...

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Petey P. TwelveMay 11, 2025
My student, Zach, has been working to debug why our bottom tape unit has been misbehaving. We are fairly certain that the issue is a short in the interface cable between the top and bottom units, because the problem appears on whatever unit is on the end of the daisy chain. Stay tuned. But in the process of monkeying with it, there was a period of time where they both worked just fine! #dec #pdp12 #pdp #retrocomputing #vintagecomputing #umdpdp12
Petey P. TwelveMar 22, 2025

Hi all, we did our annual PDP-12 demo in Dr. Ted Pedersen's architecture class on Tuesday, and it went really well.

In cleaning up / reorganizing after showing off our artifacts, I realized that we have something that I haven't seen on @bitsavers, but I maybe just didn't know where to look. It's a big poster of PDP-12 instructions -- it's kind of like the pocket reference in poster format. It is about 9.5x30 inches (24x76 cm). I scanned it in two pieces on the office machine and stitched it together with GIMP. I'll try to make a PDF version with OCR text. @bitsavers #vintagecomputing #retrocomputing #pdp12 #pdp #dec #umdpdp12

Petey P. TwelveMar 18, 2025
Today was PDP-12 demo day! #vintagecomputing #retrocomputing #pdp #pdp12 #umdpdp12
Petey P. TwelveMar 18, 2025
A TU-55 LINCtape drive from a PDP-12 in action. #vintagecomputing #retrocomputing #pdp #pdp12 #umdpdp12
Petey P. TwelveDec 17, 2024

From the DEC OS/8 Handbook https://bitsavers.org/pdf/dec/pdp8/os8/OS8_Handbook_Apr1974.pdf (1974). Personally, I think they're really underselling themselves.

#dec #pdp #umdpdp12 #vintagecomputing #retrocomputing #basic

Petey P. TwelveSep 7, 2024

Our PDP-12 (#435) is able to read tapes (but not yet write them). This OS/8 tape is close to 50 years old and still reads well. Here we use the TYPE command to print a long listing stored on multiple tape blocks. LINC and DECtape was able to be used as random access storage (like a disk). The block numbers were written forwards and backwards on the tape so that they could be read regardless of the motor's direction!

In this video, we have a tape mounted on the top drive and have already booted. Zach requests to print the file to the (virtual) teletype, and the blocks of the file are read in sequence.

https://youtu.be/X_GP_L6hK6U

#umdpdp12 #dec #pdp #pdp12 #retrocomputing #vintagecomputing

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Petey P. TwelveJun 18, 2024
Here's a PDF for the FabriTek Model 8 Add-on Core Memory for the PDP-8 and PDP-12 -- this is the device that Vince's MM8/I memory expansion emulates (or replaces). (Thanks, Bitsavers, as always!) http://www.bitsavers.org/pdf/fabritek/model_8/400-0226-00_Model_8_PDP-8_24kCore_197401.pdf #umdpdp12 #pdp-12 #pdp-8 #pdp #dec #VintageComputing #RetroComputing
Petey P. TwelveJun 18, 2024
Today, Zach and I got Vince Slyngstad's PDP MM8/I memory expansion installed in our PDP-12! No magic smoke got out, the computer booted, and appears (from console and diagnostic checks) to have 32kW of memory! The PDP-12 only had room for 8 kW inside, but could connect to an external box that would include up to 24kW of additional core. Vince's expansion plugs into the five flip chip slots that would normally lead to the external unit. All memory hardware is on those five cards, with a six card providing an electrical connection. More soon! #umdpdp12 #pdp12 #pdp #dec #RetroComputing #VintageComputing
Show threadPetey P. TwelveJun 8, 2024
A video from the same session: #umdpdp12 #pdp #pdp12 #dec #RetroComputing #VintageComputing