#pdp12 — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #pdp12, aggregated by home.social.
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Hey #RetroComputing folks! I'm running #LAP6 on @larsbrinkhoff's #LINC emulator! #VintageComputing #PDP12
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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
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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
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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
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Today was PDP-12 demo day! #vintagecomputing #retrocomputing #pdp #pdp12 #umdpdp12
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A TU-55 LINCtape drive from a PDP-12 in action. #vintagecomputing #retrocomputing #pdp #pdp12 #umdpdp12
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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.
#umdpdp12 #dec #pdp #pdp12 #retrocomputing #vintagecomputing
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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
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A video from the same session: #umdpdp12 #pdp #pdp12 #dec #RetroComputing #VintageComputing
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PDP-12 #435 playing Spacewar! for the first time in over two years thanks to some debugging by us and our much more experienced friends on the VCF forums.
First, we noticed that minicom was inserting CRs in front of LFs when sending paper tapes, so we switched to a different paper tape sender, and second, someone pointed out that it looked like our 2nd 4K core was not inserted correctly (two cables were backwards). Fortunately, the magic smoke didn't get out.
The machine booted up like a champ, and April and Zach got their first chance to play the original deathmatch game. 💚
#umdpdp12 #pdp12 #pdp #dec #VintageComputing #RetroComputing
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Well, our eagle-eyed and experienced friends on the VCF forums noticed something that seemed a little weird about our PDP-12... the W025 cards for Field 1 were not crossed, but were parallel like the ones for Field 0. (Seems logical, right?)
Looking at old photos showed that Field 1 used to be crossed, just like some other PDP-12s we know about.
Zach and I swapped the cards back today and...
#umdpdp12 #pdp12 #dec #pdp #RetroComputing #VintageComputing
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We scoped the '12, got some useful information, and did not let any magic smoke out! https://forum.vcfed.org/index.php?threads/pdp-12-435-at-the-university-of-minnesota-duluth.1241469/post-1388752 #umdpdp12 #pdp #pdp12 #dec #retrocomputing #vintagecomputing
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PDP-12 demo went great! #pdp12 #pdp #vintagecomputing #retrocomputing #umdpdp12
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Giving a presentation on the PDP-12 tomorrow, so Kyle and I did a little comparison of the PDP-12 and the Google Pixel 8 Pro:
- Of course, the PDP-12 is 12-bit (0-4096) while the Pixel 8 Pro is 64-bit (0-1.84x10^19)
- PDP-12 instructions vary, but are commonly 1.6usec each. The Pixel 8 Pro has 9 cores of varying speeds, but we estimate that it is around 1,300-11,000 times faster depending on how you calculate it
- The Pixel 8 Pro has a *million times* more RAM than the PDP-12 (8GB vs. 8KB)
- If crushed into a powder, approximately 7,000 Pixel 8 Pros could fit into the space occupied by the PDP-12 (a Pixel 8 Pro occupies approximately 1/7000th the volume of the PDP-12)
- A Pixel 8 Pro costs about $1,000, while our PDP-12 would have cost approximately $400,900 in 2024 dollars (it was $54k in 1972)! (Conversely, a Pixel 8 Pro would have cost about $135 in 1972 dollars!) In other words, the Pixel 8 Pro is 400 times cheaper than the PDP-12.
- Millions of Pixel phones have been sold, to say nothing of all Android phones -- while only about ~725 PDP-12s were sold. The PDP-8, a *wildly successful* minicomputer sold only about 50k units.
#pdp12 #pdp #dec #retrocomputing #vintagecomputing #umdpdp12 -
So my old friend @spacehobo wrote an implementation of Hellorld! for the PDP-12, and getting it to run was quite an adventure. How old of a friend? What's Hellorld!? How quite of an adventure was it it? Watch and learn -- you won't regret it.
(Nick also did a "takeover" of our channel and produced this video, so it is well above our standard sub-standard quality!)
#umdpdp12 #pdp12 #pdp #dec #retrocomputing #vintagecomputing #hellorld
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https://youtu.be/zcP_Dfgvuo8 ← Here is the video I did with @tastytronic explaining the `HELLORLD!` code, and documenting the entire debugging saga—complete with actual photos of my printouts at the pub, and videos of blinking console lights!
#pdp12 #pdp #vintagecomputing #retrocomputing #dec #HELLORLD
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I may have just succeeded in making Usagi Electric's #Hellorld challenge work for the #pdp12. I'll have to wait to see if I can cajole @tastytronic to try this on actual germanium.
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A week or two ago, we got Kaleidoscope to run on the PDP-12! We haven't found and repaired any broken flip chips. So, either all the "percussive maintenance" we've been doing in the process of testing flip chips has paid dividends, or -- more likely -- I tried to run it in 8-mode last time... it is a LINC program. Anyway, enjoy these GIFs. #umdpdp12 #pdp #pdp12 #dec #retrocomputing #vintagecomputing #minicomputer
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A couple weeks ago, for no apparent reason, the hits to our PDP-12 channel on YouTube went through the roof (for us). Then, as quickly as they came, they went! Oh well, glad I didn't quit my day job, and as @spacehobo pointed out -- the PDP-12 is *part* of my day job. 🤣 💚
https://www.youtube.com/playlist?list=PLHnc49MScQBBIlVIirpZ1Zjdh91U5Q6-6
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Ever wondered how to turn your 1970s-era PDP-12 minicomputer into a manual musical instrument, kinda like a really crappy theremin? Well, wonder no further! In this video, I provide the source code and performance technique information necessary to do just that! https://www.youtube.com/watch?v=HHepkRo7yRI
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My friend @spacehobo saw our PDP-12 wallpaper in the background of one of our videos and wanted a downloadable one, so here's two of them in 1080p. His interest has inspired me to make higher-res versions available in multiple DEC liveries. We also have a special PDP-12 version based on the nameplate at the top of our machine, but it's not ready for the limelight. Enjoy, and stay tuned!
#umdpdp12 #pdp #dec #retrocomputing #vintagecomputing #wallpaper #pdp12
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An M117E (left) and an M117C (right). The pinouts and logic are the same, but the etch (the traces) and chip layout are different. We think the rev C cards may have been put into our machine as part of a repair.
#umdpdp12 #dec #pdp12 #pdp #vintagecomputing #retrocomputing
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The #umdpdp12 is serial number 435. According to this 1978 document from #DEC, the total number of #pdp12 #minicomputers ever produced should be 765: https://archive.org/details/bitsavers_decBooksDE78_60225737/page/n93/mode/2up
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I wrote a short series of help commands in #PunyInform for an #InteractiveFiction project. I wrote a short `intro` verb, a longer `help` document with the most common verbs needed to win the game, and a `stuck` verb that tells the user not to panic before advising on strategies for solving the puzzles.
I then decided to remap the StrongSub verbs over to my new StuckSub, so that it can catch anyone swearing at the game in frustration.
And yes, I included the #umdpdp12 #easteregg, where they found a command log of someone swearing at "this stupid chunk of germanium". I decided to make the help system replicate the #os8 error message in honour of this moment in #pdp12 #VintageComputing history.
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The nameplate on our PDP-12, found inside the case. #umdpdp12 #retrocomputing #vintagecomputer #pdp #pdp12 #dec
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Here's a recent local news segment from someone visiting the museum where the #DigiBarn #LINC was last year, apparently. If you go to the museum Web site the #pdp12 in this shot seems to be on a general floor exhibit. The piece talks about how Wilkes got out of computers to become an attorney.
https://youtu.be/VymT3KnSvAM?t=7 -
Gentle update: I originally said this was the earliest LINC photo, which on review is highly incorrect.
I had conflated some stuff about how Wilkes worked on the original OS (more of a simple assembler, really) on a #LINC emulator she wrote on the TX-2. She spent a lot of time haranguing Wes and the others to pin down behaviours of the hardware so she could get it finished, but they were redesigning regularly due to the tight constraints and new flipchips coming out at #dec.
She worked with all the biomedical researchers they shipped the things to, teaching them how to get software written that worked with their experiments. Apparently that was so exhausting that she took a year off to travel the world, and in 1965 she got back to the US and found LINC had spun off from MIT and was based in St. Louis. She was still in sort of "gap year" mindset and said she'd work on the machine but didn't want to commit to any particular city. So they shipped one of the existing units to her father's home in Baltimore.
The OS she worked on there was LAP 6 (LINC Assembly Program version 6), which was vastly superior to the earlier versions. It had a full-screen text editor that took advantage of the RAM expansion modules that LINC were shipping at the time, and really made the machine more generally useful.
The OS that shipped with the #pdp12 from #dec was called "LAP6DIAL"
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OK, so where did all of this #LINC and #pdp8 stuff from this whoooole thread end up? Well, Dick Clayton from #dec explains in this short interjection at the DigiBarn event:
https://youtu.be/xT_5PcrVI9Q?t=5810
Basically Digital made a weird hybrid LINC/pdp8 system called the LINC-8, but it wasn't that great. So while he was on jury duty, he sketched out the Right Way to do it so that the system could switch between "8 mode" and "LINC mode" *in software*. The result was the #pdp12, which sold more units than all the previous LINC systems combined.
And that takes us to tonight's thread from @tastytronic, where the #umdpdp12 has just had its first successful verification tests of some of its 60-year-old flipchip cards: https://teh.entar.net/@tastytronic/109644812161500698
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Special bonus: a picture of a double-wide M706 (rev. K) teletype receiver card under test.
#umdpdp12 #RetroComputing #VintageComputing #DEC #pdp #pdp12 #FlipChip
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Finally, here's a glam shot of the FCT with an M617 installed. Thanks for joining me on today's project! Special thanks again to @neale and @ckape for the hardware donation, which saved this shoestring project close to $200.
Major thanks to Vince Slyngstad for producing Warren's design, making it RPi-compatible, and making a 3D-printed base -- not to mention selling me this kit pre-assembled -- this is a pretty sweet package and will go a long way towards helping us keep the our PDP-12 up and running for years to come.
If you're interested in learning more about our PDP-12, or donating to the fund supporting this project, please see https://umdpdp12.blogspot.com/ or check out our videos on YouTube: https://www.youtube.com/playlist?list=PLHnc49MScQBBIlVIirpZ1Zjdh91U5Q6-6
#umdpdp12 #RetroComputing #VintageComputing #DEC #pdp #pdp12 #FlipChip
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Here's a video of the tester running a "fail stop" test -- testing the chip over and over again, stopping only on a failure.
#umdpdp12 #RetroComputing #VintageComputing #DEC #pdp #pdp12 #FlipChip
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It works! Here's a picture of the fully assembled unit, with an M617 in and powered, and a successful test on the screen behind it.
#umdpdp12 #RetroComputing #VintageComputing #DEC #pdp #pdp12 #FlipChip
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While @tastytronic is setting up the new more powerful #dec #flipchip tester (in its snazzy #pdp12 livery!), I went to re-watch the videos about the tester that the #umnpdp12 project uploaded to YouTube. The last one ended with a classic fix (CLEAN THE CONTACTS, LADS) while diagnosing the LINCTape, and they didn't even test the cards before making progress: https://youtu.be/aiHSRF_2bmk
I did a bit of digging into #LINCTape and #DECTape over the past couple years, and so here's a #VintageComputing thread with some of the backstory on these tape formats.
Spoiler: The answer is *always* MIT Lincoln Labs.
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While @tastytronic is setting up the new more powerful #dec #flipchip tester (in its snazzy #pdp12 livery!), I went to re-watch the videos about the tester that the #umnpdp12 project uploaded to YouTube. The last one ended with a classic fix (CLEAN THE CONTACTS, LADS) while diagnosing the LINCTape, and they didn't even test the cards before making progress: https://youtu.be/aiHSRF_2bmk
I did a bit of digging into #LINCTape and #DECTape over the past couple years, and so here's a #VintageComputing thread with some of the backstory on these tape formats.
Spoiler: The answer is *always* MIT Lincoln Labs.
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While @tastytronic is setting up the new more powerful #dec #flipchip tester (in its snazzy #pdp12 livery!), I went to re-watch the videos about the tester that the #umnpdp12 project uploaded to YouTube. The last one ended with a classic fix (CLEAN THE CONTACTS, LADS) while diagnosing the LINCTape, and they didn't even test the cards before making progress: https://youtu.be/aiHSRF_2bmk
I did a bit of digging into #LINCTape and #DECTape over the past couple years, and so here's a #VintageComputing thread with some of the backstory on these tape formats.
Spoiler: The answer is *always* MIT Lincoln Labs.
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While @tastytronic is setting up the new more powerful #dec #flipchip tester (in its snazzy #pdp12 livery!), I went to re-watch the videos about the tester that the #umnpdp12 project uploaded to YouTube. The last one ended with a classic fix (CLEAN THE CONTACTS, LADS) while diagnosing the LINCTape, and they didn't even test the cards before making progress: https://youtu.be/aiHSRF_2bmk
I did a bit of digging into #LINCTape and #DECTape over the past couple years, and so here's a #VintageComputing thread with some of the backstory on these tape formats.
Spoiler: The answer is *always* MIT Lincoln Labs.
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While @tastytronic is setting up the new more powerful #dec #flipchip tester (in its snazzy #pdp12 livery!), I went to re-watch the videos about the tester that the #umnpdp12 project uploaded to YouTube. The last one ended with a classic fix (CLEAN THE CONTACTS, LADS) while diagnosing the LINCTape, and they didn't even test the cards before making progress: https://youtu.be/aiHSRF_2bmk
I did a bit of digging into #LINCTape and #DECTape over the past couple years, and so here's a #VintageComputing thread with some of the backstory on these tape formats.
Spoiler: The answer is *always* MIT Lincoln Labs.
