This video demonstrates how one programmed a 1970's era minicomputer using switches and paper tape. Additional information about the project can be found at: acad.depauw.edu/~dharms/pdp11
Thank you. I went to work for Digital in 1978. I worked in training. I was both teaching RSX-11M on a PDP11-70 and Introduction to Computers on a PDP11-20 using papertape. I had the bootstrap almost memorized. I always carried, in my back pocket, a small card with the instructions - toggle in the bootstrap, use it to load the Absolute loader. Then as you said, load the editor; then the assembler; finally the program. The computer had memory - completely blank memory.
Memorise the loader??? No way, I have no memory, and the number of tries I made before the paper tape reader whizzed into action are too many to admit to. RSX was adorable. I wish it was still around.
Very fun and informative set of videos! My dad has worked for HP since the late 70s and he was trying to explain to me how they used a PDP11 and I was having a bit of trouble grasping all the things he was talking about. These videos explain everything well and I enjoyed the campy acting.
2:26 "There's really no time for that right now." Actually, they have all the time they need. They have a TIME MACHINE. I'm the one without a time machine, who's not getting the last 5 1/2 minutes of my life back. Love the Deep Purple background music.
Nice Video. Brings back a lot of good memories. I'd kill for another hour again with my old PDP 11/45. Still remember LOGIN 35,1. 1.4 meg 14" disk packs. Those were the days!
I was to the marketing guy for the 11/10 which was exactly like the 11/05 except for one thing, the bezel. The 11/05 was originally targeted for the Orginal Equipment Market, OEM and the margins were very low. The marketing and sales cost for the end-user market was much greater so we need more money for the computer. There we created another model for that market. As I remember it was $500 more. I also had to explain the difference between the 11/05 and 11/10. Never lied just told the truth. The only time a program was toggled in was to run a loader for paper tape input or some other device. The teletype was the cheapest loader and was very slow. Its speed was 110 baud.
Cool, groovy and far-out man. This is better than a full DVD collection of The Partridge Family. I didn't know people walked around with mop heads on their heads in the 70's. I learn something new everyday.
mipmipmipmipmip they called it a “holodeck”, then they beamed away like it’s a transporter, and now you just called it a time machine. I demand answers.
A PDP 11 was the first computer I ever used - at University in 1973! No screen just a teletype. This was in a Science department and we were just being given an introduction into using the department's machine in case we needed it. We only needed the switches for the address of a tape drive which then loaded a learners language called FOCAL which I have never heard of since which was a bit like a simplified FORTRAN.
I had to take two assembly language courses to get my BS in Computer and Information Sciences. The first was assembly language for the IBM mainframe computers. The second was for the PDP-11 (I still have the textbook.) Assembly language for the PDP-11 was very different than for IBM and at first very confusing. Once I got the hang of all the different addressing modes, it seemed easier, very flexible and I enjoyed it. The IBM assembly language seemed primitive in comparison.
Correction when I say primitive I meant that even on a system with no disks and just paper tape you had better programming tools avaialble on paper tape. the PDP/11 here was more than powerful enough to do a whole lot more than just toggle switch programming, particularly if you added some disks and a terminal. even without disk you could load standalone editors and compilers from paper tape and do more traditional programming, there was even standalone DDT which was a debugger.
This video definitely served it's purpose of introducing the PDP. I'm working on building a clone of the Altair 8800, and am always interested in the 70's technology. Thank you for making the video. Could you share a link to watch the fifteen minute show? I believe this show had some of the same actors, directors, etc, but I haven't been able to find it.
Being a DEC technician we used the console to toggle in minimal code like to print letter a to the attached printer. That told us that Cpu and memory is basically working. Typical repair time about under 15 min. To repair disk drives and tape recorders takes longer. Memory boards been pretty expensive in the days. A car crashed into my trunk and damaged my spare part containers. 90% of the total damage was on my parts, 10% on my car.
I hope your parts are better now. I had 3 cracked ferrite beads in the core memory. The DEC quote was outrageous. A third party guy rethreaded them for 300 pounds Did you about the memory overheating test program? It worked, so was withdrawn.
"so anyway I have this holodeck that can literally transport us through time, wanna try it ?" Girl : "yeah sure whatever I have a spare 10 mins I guess"
In fact, the PDP-11 demonstrated here did not have an OS running on it. Everything had to be loaded from paper tape, and the image on the tape included everything needed by the program. Simple, but a pain in the butt to use!
The students who produced the video took the music from the audio library our production studio purchased. Unfortunately, I can't seem to locate the tracks they used. If I find it I'll let you know.
I remember back when I bought my first PC in 1987 (a 80386), I went with a 40MB hard drive (Seagate ST-4051) and a buddy who was a PDP-11 programmer and operator told me I was wasting my money to buy a drive that big that I would never fill it up. I still have that hard drive and now wonder if I will ever be able to see what's on that drive.
Flying back in time about 15 years would not give that big differences today. The first gen i7 was already out and a just above average machine would well be able to run Win 10 and by your daily driver in 2023....
WOW! That's a big fat 11M! I came along a little later in the miniaturization process! Buy the way, why is he standing and she sitting while she always looks sort of AT something at reading level instead of at him?
Hey! I saw those BC++ manuals on the shelf at 2:27! That compiler wasn't even around when the pdp-11 was contemporary. I hope someone got (geek snort) fired over that error :)
I seriously doubt many people did programming that way even with such a primitive system, there was a large library of paper tape programs including a fortran compiler and assembler and debugger that loaded off of tape and could edit and compile back to tape programs from the TTY.
Just kidding about the epic fail part. This is a good video, flipping those switches was the act of "Entering the program!" And the programming was done using those binary op codes.
Wasn't this the machine on which Unix was built and being run? And you could plug a terminal and a keyboard in it. If so, you didn't really need to use any low-level action like in this video, right?
+James Murphy The odd "1" grouping for MSB then the rest in 3's to satisfy octal is weird, Hex would have been better, everything grouped in 4's (4 groups of 4) for the 16-bit keypad
+James Murphy The PDP-11 instruction format contained several 3-bit fields (e.g., a 3-bit register field, a 3-bit addressing mode field), so octal was not a bad choice, even with the odd "1" grouping in the high order bit.
I guess I am now the previous generation :(The alternative was on a mainframe - there you would get one, maybe two edit/assemble/run cycles through in a day. Editing was of course easier - you could at least read, shuffle and, occasionally drop, those punch cards
John Lindley it also helped you learn good programming practices, such as running the code in your head before inputting it to figure out if it works. Inputting a half-assed program would have been costly. Computers these days make it too easy to mash together a copy/pasted mess of spaghetti code, because you know you can always "fix it later".
Thoughts so. It looked more like it would be done in the 60s or on 70s hobbyist computers, not on a machines bought my a major organization such as the army or a university.
I copied someone else’s homework without reading the questions. The teacher wrote across the top of the paper, “nice work JOHN”. One question was write your name in hexidecimal; … oops.
Galfonz Hello world appeared in Brian Kernighan's "1972 A Tutorial Introduction to the Language B" and Unix was rewritten in C in 1972 ON the PDP-11. Oops?
In case you want to play with one at home via software (with a virtual panel) www.retrocmp.com/projects/blinkenbone/blinkenbone-software/176-blinkenbone-download-and-run-simulated-panels-for-free
Hate to say this but this is about USING a PDP-11 to create and run programs. Not really about programming. Programming is about understanding how to use the machine's instruction set or a programming language to take you one or more levels above the machine's instruction set. Then you get to use it with the kind of instructions in this video. PDP-11s were most of my career from 1976 to 2012. This iron is small really ... the 11/10 processor itself occupies maybe up to a quarter of that rack. There are other 11 models that are as large as 4 or more of those racks and others that are about the size of an original PC box by using a processor on a chip. The 11 microprocessor itself was about the size of 2 modern CPUs.
@@stuartbrook6127 and I explained how you could be less of a troll and you respond to it with a trolling comment, being "I know you are but what am I". Embarrassing. Go make a video explaining how things actually are if you care, otherwise stop complaining when you offer nothing.
@@rodmunch69 There was no need for a video to explain what I wanted to point out. If you are so insistent on making videos, then perhaps you would like to produce one in a feeble attempt to insult me further.
