I Bought a PDP-11/83!

[@itoh8788]

Hello, I'm a Japanese old software engineer , I used to work for DEC Japan. I'm very interrested in your restoreing the PDP-11/83. ありがとうございます。 I didn't expect you can speak Japanese, Your Japanese is excellent !

[@UsagiElectric]

Thank you! It's been a while since I've been back to Japan, but I want to go again soon. いつかDEC日本の時の話をぜひ聞かせてください！

[@markcummins6571]

That "power thing" was called a power controller and it was a building box component utilized in all our equipment. I was a DEC Field Service Engineer. If you short the center pin of the three-pin connector block to either side and the toggle is in "A" position it will turn on the controller. That lighter three wire cable goes eventually to the front power switch, to turn on/off the system. You need to be aware and trained to static potential mitigation, as that CPU and Memory are very sensitive. I assume you want it to work. Handling that gear always seemed to shorten their life span if you did not use gear to isolate. But it did need to be cleaned, I did it for a living, for decades.

[@yorgle]

Back in college, I snagged one of those from a VAX 11/780 that was being junked. Soon after, I gutted it, and just made it into a rack mountable power strip. More recently, I re-modified it to have 8 solid state relays and an arduino inside of it, so i can use it to control xmas lights, etc. :D

[@brucelytle1144]

I worked as an electrician in Silicon Valley during the late 80's. I found the PDP-11's were pretty picky about their power. The only thing that I found to work was a dedicated circuit and ground, using a Hubble Surge protected, Isolated ground, Hospital Grade outlet.

[@DMSparky]

@@brucelytle1144 so this is why as an electrician i have to install iso ground iso neutral plugs for tellers to plug in their laptops at bank branches hahah

[@n2n8sda]

Damn best me to it, I did something very similar back in the day.

[@Stoney3K]

That looks like it's intended for power failover control from dual circuits, as the switch is clearly labeled A/O(FF)/B. So there has to be another circuit that feeds in from side A, as side B is the one that it's currently feeding from.

[@halfabee]

I used to install PDP 11 in rolling mills to control the shape and thickness of aluminium foil. 1982-1984. Along with multiple 8080 boards each one controlling a different aspect of the mill. The PDP 11 wa the controlling computer. At that time the PDP 11 board rack was installed vertically in the cabinet. My company placed the PDP 11 horizontally in the rack underneath was the multiple 8080 boards and power supplies. The company also developed custom I/O boards which fitted in the PDP 11 rack. There were also other boards in the rear rack. For its time the distributed computer control system was very advanced. There was also 8080 boards in the user interface panel, Spray solenoid driver (Which controlled the cooling of the mill rollers based on instructions given by the PDP 11) . I used to deal with the hard wear another person dealt with the software in the PDP 11 using machine code. Then the 8080 boards were programed in house in machine code for their individual function once programmed they were never changed on site. It would take three months to complete the installation and fully program the mill functions. The mill itself was never out of action except for the physical additional activators required to control the mill and coolant. The rolling mill productivity going from a manual system to fully automated was increased 100 times.

[@honkhonk8009]

I wish I lived back at that time. Back when CS wasnt infested with tech bros and 3 week codecamp retards. Now I gotta pray my job dont get outsourced to the third world. Now im wondering if Electrical Engineering the play.

[@hatpeach1]

Fascinating stuff! My high school bought one of these when I was a sophomore... ca. 1980. The computer was kept in the only room in the school that had air conditioning, making it the place to be on hot days. There was eight or ten teletype terminals connected to it that the students were allowed to use. The computer was kept behind a wall partition. The computer science teacher, Bob Russel, took about a year to learn how it worked, and those of us lucky enough to be around got to play with the terminals during the summer months if we showed up looking for something to do. Eventually, the machine was used for administrative purposes for the school, but during that summer one of my friends learned how to program a man-in-the-middle attack, which he ran on each terminal and collected all the passwords for all the accounts, including Mr. Russel's administrator account. Another friend wrote a statistics program for the bowling club, with very detailed information about every game in the league, with beautiful print outs generated every week. For me, I just got really good at playing Adventure and learned that machine language was brutally hard. None of us students were allowed to go near the computer itself, so this is way interesting. Thanks for sharing!

[@lucasrem]

why he needs teletype terminals, running what ? mad guy, garbage levels,, not needing the junk ?

[@martensjd]

@@lucasrem Presumably the teletypes were connected to the 11 for interactive I/O

[@Canthus13]

Mine had one when I was a freshman... around 1988. it was stuffed in a corner of the office.

[@exidy-yt]

Before I even watch this, MERRY CHRISTMAS To you and all your family, Usagi! Thank you for sharing your love of antique computing technology with us all, and all the best in 2023!

[@MichaelStrautz]

Ditto

[@AlistairGale]

I’m not an antique goldarnit 😅

[@UsagiElectric]

Merry Christmas to you and yours as well! Hope it was an awesome holiday for you!

[@michaelfaklis8169]

WD-40 will dissolve the tape residue. I always wanted my own PDP-11. While getting my degree in Computer Science in the 70s, I studied many machine's assembler languages. The PDP-11 was my favorite. In one class, we wrote a PDP-11 interpreter that ran on a Univac 1108. I started studying DEC Handbooks in 6th grade. When I worked for University Computing Company, our timesharing network was based on PDP-8, and PDP-9. The network was the front-end to access the Univac 1108 and the IBM 360s. You might have rekindled my PDP-11 obsession started in college. I'll be watching.

[@fixitalex]

Wow! PDP-11! We got plenty of great things based on this architecture in Soviet Union. First home computer in USSR was actually compatible!

[@SimonB6706]

You need to get yourself a VT220 to go with that! In the mid 1980s I worked in an industrial power station control and instrumentation lab full of DEC computers. We had a PDP11/44 running multi-user RSX and RL02 drives for system and application S/W development. The PDP11/44 was linked to dumb VT100 terminals that were on trollies in our office area. In the lab there were many PDP11/23 and then later PDP11/73s for specific projects. We used RL02, RX02, TU58 and later on hard storage devices. About 10 years ago I visited one of the power stations I word on in 1980, and there was a PDP11/73 still in use as a data logger and my name was still the password 🙂

[@herauthon]

it's time to change your name - for security reasons !

[@riz94107]

That 50-pin connector was used in some SCSI setups back in the day. Never used a PDP-11 myself but it's definitely the right vintage

[@wtmayhew]

I was going to say SCSI too. The DLT tape drive is probably SCSI connected.

[@loginregional]

@@wtmayhew As soon as I saw it, I said "SCSI" -- But I've never touched this machine.

[@lostcarpark]

That was my thought too!

[@lostcarpark]

It's also possible that the Maxtor hard drive uses SCSI.

[@jeremybarker7577]

@@lostcarpark It's labelled as a RD54 and in common with other DEC RD5x drives uses the ST506 interface with 2 ribbon cables.

[@prgnsean]

The very first computer i had access to was a PDP-8 that my high school bought - VERY forward thinking for a public high school in the 70's. It launched me on the career I still have today 40+ years later. In college we had a PDP-11 and they also installed a VAX 11/780 the summer before my freshman year. I used to be able to make VMS do *anything*. It was a terrific OS with lots of fun capabilities. Really looking forward to seeing this thing come to life!

[@TesterAnimal1]

I was a RSTS and VMS internals specialist too, I had that grey wall (it was an orange wall before that) memorized.

[@fredbullmer273]

Sean, where did you go. Same story in the Chattanooga area/Ft Oglethorpe HS that I went to. '78

[@ifrit05]

I was always fascinated how DEC was able to evolve the PDP-11 architecture over the years (Going from a huge main-frame unibus, to the micro q-bus, evolving into the vax-11). Excited for the series!

[@lawrencedoliveiro9104]

VAX was an entirely different architecture. The biggest limitation of the PDP-11 was the 16-bit address space. I remember one OS, RSTS/E, evolved increasingly creative ways to try to work around this, using various different processor modes in ways that they were not originally designed for.

[@UsagiElectric]

Thank you! I've still got a ton to learn about the PDP-11 architecture, but this one definitely feels like a great beginner 11 to start with!

[@SeaMower]

@@lawrencedoliveiro9104 The original 11/7xx VAXen had Unibuses and had to use Unibus peripherals, and could even run PDP11 programs in a PDP11 compatibility mode that was deemed essential to preserve existing customer RSX11 and RT11 developed software. That architecture decision was a central part of Tracy Kidder's book, The Soul of a New Machine, which documented Data General's reverse engineering of the VAX, and their design of the DG Eclipse series. PDP11s used memory management to access up to 4MB on models like the 11/7x series (and the later 11/83).RSTS's big problem was attempting to do time sharing, which involved fast context switching between users and the OS.

[@crb456]

I used to manage and write assembler programs for VAXes in the 1980s. One thing that struck me was the way DEC reused bus architectures in a hierarchical way as new busses were designed for more powerful machines. In the PDPs the Unibus was the main CPU-memory-I/O bus. One the early VAXes it remained as an I/O bus but was superseded for CPU-memory use. If I remember correctly this practice continued for a number of bus architectures over the life of the VAX range.

[@chrissaltmarsh6777]

I used one of they at CERN, way back. 50 years ago. Storage was its core, front panel start switches, something for boot I can't remember and vacuum loaded tape reels for data. I lusted after a VAX. The other thing was an IBM/370 mainframe but that was no good for the realtime experiment. My phone has more oomph now..

[@mitchlichtenberg1858]

This is going to be an interesting series! I worked at DEC in the 1980s,, seeing those components brings back memories, like your RD54 drive and what is presumably your TK50 tape unit with a tape still inside -- def be careful on that one, it's unfortunate the tape is still in it, lots of mechanical stuff will need to work to get it to rewind the tape and eject it. Fortunately a machine of that era should have lots of documentation and software in the archives.

[@c1ph3rpunk]

Ah, yes, the Time Killer.

[@mitchlichtenberg1858]

@@c1ph3rpunk indeed, I think those drives had more failure modes than operational ones.

[@KameraShy]

And hopefully parts floating around.

[@idahofur]

I was not happy to see a tape in it. I wonder if he should manually eject the tape and make sure it isn't stuck to the heads.

[@mitchlichtenberg1858]

@@idahofur I'd hope that it's not actually loaded but the tape is in the drive. Those TK50 cartridges contain only the tape, and no take-up reel - there's a complicated mechanism to pull the tape into the drive and spool it on the internal take-up reel, and if memory serves the read/write head is a helical scan thing like a VCR.

[@marsbux-tech]

A PDP-11? That's some serious hardware, previously used to teach assembler to college students decades ago.

[@simonwilliams5265]

Yes, that was the first computer that I used in second year of university to learn assembly language! Would have been around 1982.

[@Lee_Adamson_OCF]

Get yourself a "qbone" from the DECromancer. You can use it to emulate hardware while you test and restore it piece by piece, and it can stand in for your missing storage devices. As a qbus -11, parts will be cheaper, which is good lol. I run an 11/73 in a Heathkit H-11 enclosure with 4mb, ethernet, and uc-07 scsi + a BlueSCSI emulator. Makes for a great 2.11BSD machine. The 11/83 is a great CPU. You got a good machine there.

[@jaredwright5917]

A new space heater for your new space, and in good condition. There's tons of software and hardware to play with for these systems. There's also a company that still makes blank PCBs for it. I've heard that the original DEC power supplies frequently need to be rebuilt/recapped before use if they've been sitting for a long time.

[@wtmayhew]

The capacitors can go dry. The electrolyte is hygroscopic, so very dry operating conditions or storage is not good. Sitting for a long time may require the electrolyte to be depolarized. The trick on old radios is to apply increasing voltage gradually over the course of hours using a Variac. That trick doesn’t always work well on a switcher supply, so new capacitors may be easier. In power supplies where there is continuous significant AC current through a capacitor, the capacitor will wear out after several years of continuous use.

[@Aeduo]

Can it play bad apple?

[@geoffroberts1126]

Applies to any electronic device with electrolytic caps. Other caps are usually ok in something that old. I don't think DEC ever used tantalum caps which are another known source of trouble. I'm doing up an old Microvax at the moment, which initially powered up fine for about thirty seconds, was in the process of booting, then there was a continuous smoke plume from the PSU, like a roman candle lol. Shut it down and in the process of recapping the power supply. Electros do not age well, particularly when not in use.

[@erikkarsies4851]

@@Aeduo Perhaps it can... there is a text based version for the PDP11 called PDPAPL on Github, but I can't find it on KZbin

[@Aeduo]

@@erikkarsies4851 hah sweet.

[@TheErador]

Just when I thought this channel couldn't get any better... PDPs (and minicomputers in general) were expensive, any organisation that bought one wasn't gonna waste any drop of computing power, so time share operating systems were born, and hence all the terminals that could be connected to it.

[@SeaMower]

Timesharing happened in the 60s on different DEC models, as well as models from other companies. The minis were for low cost laboratory and small business systems, which included low cost time sharing. Until the demise of the 36 bit Jupiter in favor of the VAX 8600 Venus in 1983, the PDP10 architecture (DECsystem 10 and DECSYSTEM 20) was the king of DEC time sharing. Thats when I made the jump , and got Vaxinated, myself.

[@stevenstellman7035]

@@SeaMower Sorry, I don't know much about the hardware, but as a biochemistry post-doc at Princeton in 1971 I used a PDP-10 that fed one of the first commercial graphics computers, an Evans & Sutherland LDS-1 that we used to solve DNA and RNA structures from x-ray diffraction. The graphics was for visualizing molecules that Watson and Crick had built with wire models. The PDP-10 was for the heavy calculations, especially fast fourier transforms to relate spots on diffraction photos (yes, photos developed in real darkrooms) to atomic coordinates. What it took us months to do then can be done in minutes today.

[@KallePihlajasaari]

@@stevenstellman7035 People would love to hear first hand accounts of early research breakthroughs. You would get a loyal (probably small) following if you were simply to whiteboard your way through a few old published papers and explain stuff in simple terms. I know I would follow along just to get a better idea of how genetic research got going.

[@stevenstellman7035]

@@KallePihlajasaari Dear Kalle Pihlajasaari, I would be happy to make our early publications available. In 1971 I had just finished a PhD in physical chemistry at NYU using the CDC 6600 (Cray) supercomputer for Monte Carlo thermodynamic studies of polyethylene. I landed a post-doc at the Princeton laboratory of Robert Langridge, who had done his doctorate with Maurice Wilkins (co-Nobelist with Watson & Crick), worked at MIT on Project MAC (Machine Aided Cognition - a time-sharing pioneer), and then got an NIH grant to start his own crystallography lab. Three papers on the use of early graphical methods for nucleic acid structure are: Stellman SD et al. Structure of guanosine-3',5'-cytidine monophosphate. I. Semi-empirical potential energy calculations and model-building. Biopolymers 1973;12(12):2731-50, Stellman SD. Computer graphics in the solution of the chain deformation problem. Macromolecules 1974;7(3):296-300, and Stellman SD. Application of three-dimensional interactive graphics in X-ray crystallographic analysis. Comput Graph 1975;1:279-88.

[@KallePihlajasaari]

@@stevenstellman7035 I m going to go and look them up. Some amazing stuff has been discovered in DNA, similarly this latest offensive the world could have done without.

[@MrAsBBB]

Oh this took me back to when I was 20 , I am now 54. I spent Christmas and Boxing Day installing a pdp. After 12 hours we found we were missing a cable.. Will never forget that Christmas. It’s amazing how nostalgic one becomes for old computer equipment. Great video . All the best and Merry Christmas from the UK.

[@throblet]

Excellent. You are back in my old world. Loved my PDPs 🥰

[@davidwilliss5555]

It was indeed meant for lots of serial terminals. The first computer I ever used was a PDP-11 around '79 (I was in 8th or 9th grade). The actual computer was at the Public Schools Admin Building across town and one of the teachers had to dial a number and put the phone into a 300 baud acoustic modem. The terminal we had was a Decwriter 300 which was a dot matrix printer with a keyboard attached. The operating system was called RSTS something. I only remember that the TS stood for Time Sharing. The next year, my school got its first Apple ][ and a couple of us got the privilege of copying all the programs our teacher had over. He printed out the BASIC from the PDP 11 and we typed them in to the Apple and saved them to floppies for them..

[@westprog2012]

Before SneakerNet, where you carried a floppy from one system to another, we had PrintNet, where you made hard copies and retyped everything.

[@szaki95]

I pressed the like button before the video started! The PDP line of computers are indeed an iconic part of cumputing history, good luck with this one!

[@bayanicustodio3998]

I think DEC is the only company that published tech manuals and made it easily available in tech schools for a minimal price. I had manuals for the PDP-8 still my junk box in the basement in 1990’s.

[@szaki95]

@@bayanicustodio3998 Yeah I've read that the Unix operating system was developed at the University of Berkeley on DEC machines.

[@rianmcfie7633]

So cool. I spent a few years programming various pdp 11/70s & Vax's in the 70s and early 80s. Nice to see these things brought back to life.

[@Graham_Rule]

My former workplace used a variety of PDP11's as front end terminal controllers for a mainframe. They connected to a network of other PDP11's with many terminals connected. Oh, and I think you owe my neighbours an apology for making me shout out loud when you produced that dual mains cable death trap. Very glad to see that you were talked out of it.

[@jackpatteeuw9244]

If OP is not going to be running anything more than a couple of RD drives, a 12/3 SJOOW power cord is sufficient. Maybe a NEMA 5-20P plug. Of course that would mean the receptacle would have to be change to a 5-20R but you can still use "standard" 5-15P plugs with it.

[@WildBikerBill]

I remember in the late 1970's at college PDP-11s' were used as RJE (Remote Job Entery) terminals for submitting our programs on a stack of batch cards. The programs were read off the batch cards and submitted to the big mainframe IBM 360s' somewhere else on campus.

[@steveblackwe11]

My first time using a computer was a PDP-11. As a high school student, my school had borrowed one from Monash University and I learned to write in Fortran. It was around 1974 and it used mark sense cards and a printer for output. It began a life-long passion for programming which I now teach at the same high school I first met the PDP-11. Thank you for the memories.

[@PixelPi]

Now that's a proper minicomputer! If you need a unix expert I'm in Austin and can help you get 2.11BSD running on it. Yes it was meant to support like 30 terminals, you still need to get yourself a DEC VT220 terminal with Sixel ("six pixels") bitmap graphics support.

[@highpath4776]

And. Or add in a DEC Rainbow for fun. (could they actually be a terminal and write locally to disk at same time , I never figured that out, even though with internet or local networks I can write to any disc i have permission to find and write to

[@TesterAnimal1]

Snake oil! (Says Saint Ken!)

[@normaneverhartsr4791]

Wow!! A PDP-11 - I got my start as a computer operator working on a DEC PDP-11 mainframe. Way back in the 80's. It used a DEC operating system and a UNIX O/S.

[@Bat_Boy]

PDP-11/84 used by the Air Force, and McDonnell Douglas, CA. Worked for both in the 80s.

[@madusan1]

.love the pdp 11. I used the PDP11/34 as a minicomputer at Queen's University in Kingston, Ontario. Used 8 in floppies in a master/slave config. Compiling code. Sending output to the large Burroughs Pagd Printers. I was running Fortran most of the time but on the IBM 80 col cards punched out at my high school CS class in the mid '70s. Thanks for this. Brought the memories back even if the equipment is generations different!

[@simonwilliams5265]

Great memories, graduated Science 85 from Queen's and I remember the PDP11 from second year.

[@allenjenkins7947]

This takes me back about 40 years. We had a PDP11 (I think an 11/70), which originally had a single-sided 8-inch floppy (about 90kB from memory), later replaced with a double-sided 8-inch floppy. Later on we had a 10MB hard drive with either a 10-inch or 12-inch platter - none of your miniature 5-1/4 inch stuff. The 10MB HDD cost around the same as a luxury car or a small house. The original operating system was RT-11, later updated to RSX-11M when the HDD was installed. Later on we had various models of MicroVax, Vaxstation and Alphastation. All of which ran various flavours of VMS. None of our DEC machines ran Unix. I can't recall the brand of terminal we used as a VT100 clone, except to say that it had a much more ergonomic keyboard than the VT100 - which was blamed at the time for an epidemic of RSI. To add a bit of context, I worked for 35 years for the Australian Defence Science and Technology Organisation (DSTO), where we were always at the cutting edge of technology. We often built our own systems by adding third-party peripherals, using clone systems, or installing our own add-ons. I wouldn't mind a quid (pound or $2) for every time some DEC or other manufacturer's representative has told me "That's not user installable.".

[@mspysu79]

A very nice score, the PDP-11/83 was one of the later 11's it uses the bus called QBUS and is a slightly faster 11/73 with Private Memory Interconnect. The 50 pin cable is likely for an external 9-track tape drive. The built-in tape drive is a TK-50 and is likely dead as they were unreliable by the late 80s., it could be replaced by a TK-70 drive which will read but not write TK-50 media, and the TK70- would evolve into DLT. Although UNIX is available for the PDP-11 series remember it is a 16 bit machine and UNIX is not fast on an 11 and does not show off the architecture well, (now UNIX on a VAX is an entirely different story). You would want one of the DEC os' for the machine like RT-11, RSTS/e, or RSX-11M Plus.

[@Sven_Dongle]

The old Klondike Bar drive!

[@georgegonzalez2476]

I used to dumpster-dive at a local Macintosh peripherals company. They had lots of these tape drives in the dumpster. I tried using a few of them and they were all very marginal, only rarely able to format and test a new tape.

[@RadioNest]

Makes me smile. My first hands on computer was a PDP 11/20 when I was a Junior in college (circa 1973). 56K BYTES, high speed paper tape reader/ punch, and a multi-user Basic OS that was loaded via papertape. OS written in assembler. I wrote a DJ-11 driver, a double sided floppy driver and a plotter driver. [Your 11/83 is tiny by comparision.] Memories!!

[@chuckinwyoming8526]

Looks like fun!! A lot more documentation, OS software and hardware for the J11 and QBUS/quad-height boards for DEC then the rather obscure Centurion. I have a 1977 LSI11 and have built a full PDP11/73 front panel with blinkey lights and switches.

[@PaulFWatts]

I programmed DEC computers starting in 1978 and spent many years with the PDP-11 series: 11/23, 11/34 and 11/70. So many good memories. Thanks for this nostalgic trip down memory lane 😊

[@burzvingion]

My go-to for tape and glue residue removal is n-heptane. It's the solvent typically used in rubber cement, and can be found by the trade name "Bestine." I've never found it to cause damage to any paints, including some that were damaged with exposure to isopropanol. I recommend using it in a well ventilated room with nitrile gloves though

[@kwgm8578]

Yes, Minicomputers are multiuser machines and terminal based. The big blue, 24(?)-bit port is for a DecWriter Administrator printer/terminal, except terminals of old didn't have glass terminals, but has paper printed outputs. Then you had a written record of your session, when needed.

[@katharinelong5472]

At U. Maryland in the 80s the undergrad computing labs still had the dot-matrix DecWriter printing terminals for student use. My girlfriend (now wife) had to use them for APL programming in her linear algebra course; there were multi-character sequences to mimic the crazy APL special symbols. No fun at all.

[@the123king]

Quick thing, as someone who has restored a PDP-11/23, the power supplies in those BA23 chassis, have RIFA caps. These will definitely need replacing. The good news, is that the PSU's are quite easy to work on. The chassis you have is, i believe, "simply" 2 BA23 chassis joined together. Generally, PDP-11's are pretty bulletproof, and parts are quite available. It won't take a lot to get it working. Also, DREM hard drive emulators work well with them, emulating both RL02 drives and MFM drives, giving you many options for bootable storage. I'd recommend finding an RX50 drive. These are 5.25" drives, and disks can be written to by standard PC floppy drives (though with special software like PUTR, which is a DOS based utility that can read basically every DEC format you need. It's quite trivial to put a bootable RT-11 image together using it. Nice to see you pick up a PDP-11. Any minicomputer fan should have one in their collection.

[@lenkapenka6976]

BA23's are useful to have nowadays esp. for MicroPDP and MicroVAX II QBus build your own systems ))

[@TriumphT140]

Had one of these in my bedroom growing up - two cabinets - one was the computer one was two disc drives - took the big round ones like you have on the shelf.. Dad got it from the Antiquarian Society - came with all the documentation on fiche. I can't remember who bought it (didn't move it with us in 03 when we moved) - but it worked beautifully. I remember playing with it as a kid. God, this brings back memories. Dad and several of his friends worked for DEC - was linked this video by one of them. Good on you mate.

[@lumpytapioca5062]

When you get a 9-track tape drive, I have a copy of Xenix for the PDP-11. It's Microsoft's early, early 1980 release of Unix v7. The real thing, right from Bell Labs. Your machine would like it for running a bunch of users, and it's way more fun than RSTS/E or RT-11.

[@karstens7893]

Try WD40 on the tape residue. Works great and shouldn't hurt the paint. Clean it off with rubbing alcohol after so it doesn't smell!

[@dankolar6066]

For removal of glue residue, consider applying strips of duct tape over the affected area. Allow the tape to remain for a time, then rip it away. The glue will like the duct tape more than it likes where it is.

[@macgvrs]

Those old PDP computers are intriguing. Neat that you now own one. You can get a 20 amp appliance cord if you need more amps.

[@BoDiddly]

This is great! I had always heard of PDP-11's when I was starting in IT, but I never saw one. They were big deals and apparently everybody that programmed them knew Cobol or Fortran for some reason...lol! I can't wait to see you dig into it! I see you have a Ti-99/4a in the background! I still have my original Grey box one (still working last time I checked in 2005) and a later White plastic one (not working). I have the Speech Synthesizer, Peripheral expansion box, 32k memory expansion, 5 1/4" floppy drive and I think about 10 cartridges for it! I remember spending so much time on that thing, especially dialing up my friends with their Coleco Adam or Commodore 64 on our 115 baud modems! I also remember spending a lot of time trying to learn Ti Assembly language! Those were the days... I want to get my hands on a DEC Alpha one day, or an SGI workstation at some point. These things were always a mystery to me as they were unobtanium (ie. extremely out of my budget), and even after SGI, they were still out of my budget. Some are STILL out of my budget...lol!

[@KosmosHorology]

I found that orange-based cleaner (containing D-Limonene) can remove pretty much all glue/tape residues very effectively when other solvents failed. Just watch that paintwork!

[@MLX1401]

I have this stuff in a CRC-branded can, and it's really good! Do not use on polycarbonate or polystyrene, though.

[@psears27]

Try using WD-40… Something you might already have on-hand.

[@MLX1401]

@@psears27 Yeah, WD-40 is also great, but seems to work best for sticky tape residue. That PDP-panel residue looks dry 🤔 I see people in the comments using IPA to clean WD-40 smear, but IPA does hurt some metal powder paints. Also, IPA is a bit overkill as WD-40 comes easily off with any basic household cleaning spray 🙂

[@andrewkepert923]

Eucalyptus oil is also pretty good on various tape residues. (.au opinion here)

[@stylesoftware]

For cleaning ancient glue? Citrus based cleaner and/or turpentine. They won't eat into the paint, and will slowly melt the glue with repeated heavy rubbing with a cloth.

[@Dsschuh]

I recently purchased some ceramic items from a thrift shop and used peanut butter to get the paper stickers and gum off -which worked really well. Let the peanut butter soak into the glue for at least 15 minutes - longer cannot hurt. You might try cooking oil with baking soda, I think that produces a mild, soft scrubbing agent.

[@dh2032]

third party removal stage agent, and soap that off !

[@michaelhaardt5988]

That makes sense: Most glues either solve in alcohol and similar or in grease/oil.

[@lawrencedoliveiro9104]

There is stuff in the supermarkets here called “Desolv-It” -- smells like orange peel. I’ve been using it since the days of floppy disks, for taking off the labels.

[@cwc4592001]

Try Eucalyptus oil. Just rub on and rub off. Stubborn reisdue recquies some elbow grease, but it will come off and smell good as well.

[@KallePihlajasaari]

@@cwc4592001 I have a recollection that there may be another essential oil that can also be effective. Lavender and citrus peel oil might both be effective as well.

[@InquisitiveSearcher]

I worked on (fixed) DEC equipment from 78 to 89, mostly on the VAX series but on a whole lot of PDP11 equipment as well. The power controller at the bottom of the cab had switched outlets so equipment other than the computer in that cab could be powered on and off with the power switch of the computer. The computer box will have a 3 pin connector on the back of it from which you would run a cable to a matching connector on the power controller. When you flipped on the power switch on the system front panel the switched outlets would get power applied turning on other peripherals in the cab. On larger multi cabinet configurations that 3 wire cable would be daisy chained to the power controllers on the bottom of each cab, thus powering on several cabinets of equipment at the same time. The idea of the vents on the cabinet side panels is part of DEC's airflow management. That is also why the panels are so thick. The air comes in via the left side panel, the fans move the air from left to right over the equipment and exhausts through the vents on the back of the right panel. In that era of equipment (and beyond) DEC always moved air of every device from front to back. Which was not always true in older industrial cabinet equipment. Those, like with the 11/40, 11/45, 11/70 industrial cabinets, moved air from top to bottom. That long ribbon cable that went over the "bar" in the back extends the systems "Q-bus" from the system's primary enclosure to the secondary one. And if you slide the equipment back together you will find that "bar" covers the air gap between primary and secondary enclosures. So it's really not such an odd idea that the cable should loop over that "bar." The cable is as long as it is to allow either one of the 2 enclosures to be slid forward for maintenance access. Removing that disk drive, for example, if there had been a second drive beside it, would have been done by sliding that enclosure forward, taking off the top cover panel and disconnecting the cables. It all makes sense if you stop and think about it a bit. I hope it all powers up and works for you. OH! A thing to note about the "Q-bus" is that it "serpentines" through the slots. So it goes from one duel slot to one beside it, then down to the slot below it, then across to the slot beside it, then down to the slot below it and so on. In your configuration you will find several dual height modules called DZQ11s (each one controlling one of those 4-port RS232 panels) each installed in a serpentine order on the Q-bus.

[@OscarSommerbo]

The "weird upper piece" is known as a cable management tray. Or at least that was what I was told. Good to see there are a few DEC guys in the comments, I am sure their knowledge will be valuable going forwards.

[@Davedarko]

Thank you for filming that extra bit of b-roll way later for 4:49 where you put down the terminal :D

[@vincei4252]

Looking forward to you getting UNIX running on this sucker. I suspect that the blue connector with the 3 rows of connectors is a 50 pin SCSI connector. Lookup SIMH for an environment that simulates DEC machines. It may help you get to grips with the various devices that the PDP-11 has. I'm pretty jealous, if I'd seen that eBay auction I would have snapped the unit up myself. I really want a VAX-11/780 or 785 but that's just a dream

[@Sven_Dongle]

You're better off with a MicroVax II, at least that will fit through your door.

[@axelBr1]

UNIX! has to be VMS

[@Sven_Dongle]

@@axelBr1 VMS wont run on PDP

[@vincei4252]

@@Sven_Dongle It was called VAX/VMS for a reason.

[@Sven_Dongle]

@@vincei4252 Yeah, the reason is its Virtual Address eXtension, Virtual Memory system, which isnt supported on PDP. I did, however become Windows NT

[@walterwelch9894]

seeing this video makes me want to try to bring my PDP11/03 up. haven't fired it up in years. Have a Merry Christmas.

[@luke27luis]

You didn't have enough with the Centurion, did you? I know I wouldn't have either :D. Can't wait to see more!. Merry Bunmas to you too!

[@shelterit]

Og, I've got a great tip for removing icky gooie sticky stuff; eucalyptus oil! As with all things, it comes down to the age of the go, but eucalyptus oil is great at bundling and separating stuff. It may crumble a bit, which washes off easily. And the added bonus is the lovely smell!

[@PixelOutlaw]

As a LISP fan (typing it the old shouty way) it'd be cool to see some of the PDP implementations if you happen to get some. :) Congratulations on a historic computer in the collection!

[@chrissingleton6029]

Interesting purchase... congratulations. I've got 6 PDP-11's myself, from small ones to a full 5-rack - fully working - PDP-11/44 with a "refrigerator sized" tape drive and a functional RA81 hard drive (check out the videos on my channel of the RA81). Careful, as rarely does someone stop at just 1 PDP-11....

[@moconnell663]

5:19 Those "velcro things" are 3M Dual Lock fasteners. I probably have a bag of the round screw mount ones somewhere.

[@alanfreeman3062]

Years ago I operated a PDP 11/83 and the 85. Seeing it again really brings back some memories. Thanks 👍

[@CraigHollabaugh]

Your new shop isn't large enough for your passion. Merry Christmas to you, your family and everyone at Usagi. Thanks for a great content year.

[@KameraShy]

He will outgrow it in six months.

[@belstar1128]

Is Usagi rich?

[@highpath4776]

@@belstar1128 Family owns a ranch with plenty of land and space, think they rent some out as holiday shacks and so on as well as the cattle element.

[@belstar1128]

@@highpath4776 Ok that explains it farmers have a lot of land. but its not great land to live in permanently.

[@uscgspawn2298]

Brings me back to my college days, where the school had a PDP-11/44. Still remember loading the disc packs.

[@John_Mack]

Super cool... back in the 80s when I was in the Canadian Armed Forces we used these machines for our CEMIS (Construction Engineering Management Information System). We had dozens of teletype terminals connected all through the building to do Engineering reports, Project startups and even to order supplies. If I remember correctly, each terminal connected directly to the RS232 back board. The additional power was to power up external tape and disc drives as well as in cabinet drives.

[@Blashkyrk]

Supercool! I worked as a consultant on a PDP-11/83 in the 90's. It was the control system for a plasma cutter line in a steel mill here in Sweden. A funny anecdote was that when the Y2K bug craze was at it peak someone at the steel mill company hired another firm to certify all computers for the coming millennium. The firm had no clue what the PDP was so they stuck a sticker on it saying NOT Certified meaning the system needed to be fixed before the millennium. Me and my colleagues tried to convinced them it was no problem but as it had the wrong sticker on it, the PDP needed to go! Fast forward to the new years eve of 1999. Guess which newly installed system crashed? Yep, the replacement system did not survive the Y2K switch, luckily the trusty old PDP was still there (thanks to us) and booted right up and continued as nothing happened. "If it ain't broke, don't fix it!" do apply sometimes :) If I remember correctly we used like at least 10 of the RSR232 ports for the plasma cutter line. It controlled two portals with cameras and markup equipment that detected the new newly rolled steel plates outline, which had quite raw edges. After that it calculated the optimal position of the new plate to be cut out. Marked out the new plate and then used the markings when cutting it later down the line. Sometimes it gut stuck in the execution sequence (something related to priorities of the tasks that got messed up) and needed a firm kick in a*s to continue, but usually it just worked flawlessly. Good luck with this beast!

[@retrozmachine1189]

Wow, a full height Maxtor. The only time I've had hands on with one it was a 15Mbit ESDI drive in a Netware 3.0 server I installed and commissioned. It was impressively quick. This PDP series of videos is going to be interesting watching!

[@JohnDlugosz]

I had a Seagate in that size, a bit older and only 80 megabyte.

[@johnhermanson1156]

Nice job so far! Stirred up memories for me working on add-on cards for Data General Nova and Eclipse minis, a competitor of Digital. Only you seem more careful. It's good the hard drive is a bit newer; for your systems with older CMDs or SMDs, beware that head crashes were routine so just be careful and avoid any bumping or non-graceful shutdowns. New to your channel and I like how you showed respect for the performance specs of this old rig. In their day, this performance certainly didn't come cheap. A full minicomputer system to support a mid size office would cost over 100K if I recall. I know that before drives like that Maxtor came along, those CDC hard drives and controllers might be 20K. And in 1983 dollars. Partly because product development and manufacturing was so archaic and expensive. It really was a new industry and what strikes me to this day is how young most of us working in it were..

[@Barbouri]

I have been using "Bestine" solvent and thinner for thinning or reducing rubber cement by Speedball. It is N-Heptane, and is compatible with most plastics except for polyethylene. I use it often for cleaning up dried sticker residue on old test equipment.

[@ropersonline]

8:24: That female 50-pin connector is a D-subminiature standard size: DD-50. Its blue colour is probably of no consequence; back then, D-sub connectors generally weren't colour-coded (yet). It _might_ be SCSI, but I'm far from sure. Per Wikipedia, "older Sun hardware uses DD50 connectors for Fast-SCSI equipment".

[@douro20]

The tape drive uses a format called CompacTape, which was developed by DEC in the mid-1980s and was later rebranded as DLT. Versions were developed as late as 2007, and the most advanced such drives could store up to 800GB on a single cartridge, while maintaining the same physical cartridge format. All of those drives have high-speed pancake servo motors which have to be forced-air cooled.

[@mrspock2al]

Used those DLT tapes on MicroVax.which was connected to a DECNet network for office applications. It all got removed when PCs took off in mid 80s.

[@brettmcs9805]

My first job in engineering involved using a PDP 11/40 which was used to support FORTRAN IV programming and run an FEA package written by the local university. The graphics was done by a PDP 11/10. Good times!

[@ChrisCebelenski]

Cool - lots of help available on this one since they were very popular. I’ve owned a few myself (11/20, 11/40, 11/34) and this one is a bit newer. But if you get stuck on learning software etc, drop me a line - This is where I started my career before moving to VAXen. And yes, if you see a VAX, especially an older UNIBUS one, grab it - it would be a fantastic project also.

[@mikezimmermann89]

OMG… VAXen! I had forgotten that was the “correct” plural form of VAX. What great machines! I miss them

[@littlechestnutorchard]

This took me nearly half a century back. 40 years ago I used to be a process control-Instrumentation engineer and we were running a brand new fully computrised cement plant in city of Mosul in IRAQ, Entire plant run by PDP-11 by DEC. Good old days.

[@derekwhidden9730]

PDP 11 was used to program Atari 2600 games. Granted Atari itself was HQed in Sunnyvale California, but there were several third party developers that programmed games. It would be interested to find something on that hard drive.

[@VincentGroenewold]

Oh now that is cool, not just an office machine.

[@derekwhidden9730]

@@VincentGroenewold potential homebrews in the future?

[@StingyGeek]

The respect with which you treat these machines is awesome. To think that without people like you, with your skills and dedication, this important history would end up in landfill. We have lost so much already. tragic.

[@rille47]

Dude! You´re putting together a awesome collection ! :) love it - totally crazy when You consider space/raw performance, but when it comes to style and cool factor, untouchable!

[@gzk6nk]

Back in the '70s I was a DEC field engineer on PDP11s, mostly 11/05, 11/34s, and11/44s (Unibus machines). The Micro 11/23 as well (Qbus), so your machine is later than those but very similar. DEC used to issue manuals for the Micro PDP 11s in the form of paperback books, and these showed DIP switch settings etc for all the PCBs. You probably need to source those! I loved working on PDP 11s as everything (all memory and all registers) was addressable and accessible to read and write from the front panel switches and indicators. So if you selected the output register of the console printer (777466 IIRC) and deposited 101 (ASCII 'A') into it, a 'A' was printed! As an engineer and using the PDP11 programming card you could enter and execute some quite complex 'noddy' machine code programs to test aspects of the system.

[@gtb81.]

pretty sure that switch means A-automatic O-off B-Bypass . Those small connectors on the back is likely for control on the A setting, and the one that is not controlled by that is simply a standby always on socket. also the three breakers are probably separated for 10 amps on one set of sockets and one for another set, so might want to check that out before you pull 12 or so amps on it, it may be on one 10 amp breaker, possibly one each on the breaker. i could be wrong but i don't think they'd put those 15 (maybe 20) amp sockets straight to 30 amp. (couldn't see what was on the other side)

[@mbraun777]

Test the paint, in a hidden place, with acetone (low concentrations found in fingernail polish remover) and carb cleaner. Both will dissolve some paints, but may prove effective in removing old adhesive.

[@sstillwell]

I've run real PDP-8s before when I worked in the lab in college, and VMS for VAX 11/780 under an emulator...I'm still waiting for VMS Software to release their hobbyist kit of OpenVMS for x86 so I can fire up another "real" instance under KVM - Itanium and Alpha systems are harder and harder to come by as time goes on, and consume more power than I'm willing to pay for. I admire the work you're doing, though!

[@gerdbeutler3728]

In my 1st year as DEC FSE in 78 I had to do a lot of Preventive Maintenance PM to all kind of PDP/11 Equipment. And I never imagined how much dust and dirt is accumulated inside. I felt rather being a chimney sweeper than a IT graduated engineer. So I changed tons of stuck-up fans, vacuuming and air blowing the boards. If this is neglected, dust can cause overheating. Hope your antic collection will find its way into a computer museum one day.

[@letthetunesflow]

Damn! If only I had known about your brothers shop before Christmas, I totally would have bought several gifts for people from his shop! Looks like some great products, and I’m a sucker for artisan made products. I just love anything made by hand, they just tend to have more soul, and usually someone very passionate behind them. I love to support small stores when ever possible. I like to try buying products made by hand, and/or from a small business, often times they turn out to be either cheaper, higher quality, or both, and usually much better customer service… Also buying from someone genuinely passionate for what they make/sell is also a nice bonus! I’ll make sure to remember your brothers shop for the next time I’m in need of a great gift, or something for myself. Thanks for mentioning it

[@davidlawton898]

Brings back such fond memories of DEC machines ! - starting with the PDP 11/34 I learnt BASIC, Fortran & COBOL programming on with punched cards (batch card reader, eagerly waiting to find how many bugs we had, before resubmiting fresh punched cards to the reader!). Then migrating next year at Uni to a PDP 11/70 running RSTS/E, learning more advanced Basic Plus programming on VT 52/100 terminals. Then first job with PDP 8E computer as an engineer, running 8K Core Memory modules (up to 24 K max ?) and fitted with General Instrument FR500 2.8M disks (same as used in submarines from memory, with the spindle mounted horizontally rather than vertically (for depth charging resistance)). Second job was working with a TB216 disk tester working on all kinds of small DEC 11 series m/c running FMD / SMD disks, including a master m/c running pot-lines at an Aluminium smelter - where the O/S was written in German! (That was a tough fix!). Then later working with VMS / OS/X etc. Wonderful memories - thank you...

[@edgeeffect]

Excellent choice....if I could go back and retrieve just one machine from my past it would be our PDP-11/73 from college.

[@InArcadiaSum]

In the early 1980's, I ran the Computer Department of Wasey Campbell-Ewald, a major UK advertising agency on a PDP11/70, with about 50 terminals, running specialised software from Tempo, a company in the AGB Group, which was later sold to and pillaged by one Robert Maxwell. Great days of patch racks, self-loading tape handlers, disk drives the size of washing machines and 10-platter disk packs. All in an air-conditioned machine room. Then we swapped over to VAX 11/780 and up. Our PDPs in the UK came from Systime in Leeds, a DEC OEM.

[@mlmmt]

I look forward to more videos on this old thing, looks super interesting, I wish I could get into minicomputers, but I have no space for such things!

[@wtmayhew]

It tends to spike the utility bill too! I bought a Sun 3/160 which was a lot of fun, but it consumed 1.5 KW. That’s about $0.20 per hour or close to $150 of electricity used every month. Not to mention it makes the house hot in the summer! I ended up donating the Sun to a university club which didn’t need to worry about the electricity cost.

[@occamraiser]

Happy days, the 1980s when people who knew computers were actually special. I remember setting the switches on the front panel of a PDP11/45 to define the boot address. And wire-wrapping a hand made double width card for a PDP11/02 to DMA mulitple data steams onto a 1/2 inch tape drive. The tape drive, running, was absolutely mesmerizing - the vacuum columns were fascinating as they coordinated with the reels to move the tape over the heads..... many an hour wasted in a semi-hypnotic trance.

[@leeterthanyou]

$5 says you find my old account info on that old Maxtor. There are only so many semifunctional PDP-11/8X's with a fuckton of serial ports out there and at this point, it's a gamble as to whether or not you bought one of them that I had access to back in the day.

[@lawrencedoliveiro9104]

One of those “[«group», «user»]” type DEC user IDs? With the numbers in decimal (RSTS/E) or octal (RSX-11)?

[@mcreilly2]

The 11/83 is a lovely machine. I bought one in the late 90s that looked just like this one but with a pair of RA81 (456Mb) drives filling the two drive spaces. Sadly didn't have space to keep the whole thing when I moved so let the chassis and drives go to somebody else but kept the actual 11/83. Still have it in somewhat working order along with quite a few spare parts and manuals (and other Micro PDPs and MicroVAXen) collected over the years. If you have questions I'm happy to try to help.

[@Boostland]

Another potential problem with the dangerous parallel plugs could be if it was plugged into separate phases

[@BitwiseMobile]

When I was in the Navy in 1987 they had this one big room that all it had it in were these giant 14" and 16" platter hard drives with multiple platters. They stood about 4 feet tall. They looked like washing machines to me, so I called it the laundry room ;). Not sure how this popped up on my feed, but happy for it. When I was a kid I read Hackers by Steven Levy. The whole DEC and PDP story is intertwined with the emergence of general and personal computing. Bell struggled with the TX-0, just like the other members of TMRC at the time, and he remembered those struggles, and got feedback from other TMRC members like Greenblatt and Gosper to build a better machine. That evolution is what eventually brought the PDP-11. Many of the features are a direct result of feedback from those early pioneers at MIT. Incidentally, That book made me realize what I wanted to do with my life back in 1985 when I first read it. I joined the Navy to learn electronics, so I could design my own computer :D. The pipe dreams of a teenager indeed, but it brought me on this track, and I'm thankful for it.

[@LJ45Chimera]

Great to see a PDP11 on your channel :)

[@andypughtube]

They used PDP-11s to run engine dynamometers at work. The last one was replaced in 2013. With a little bit more effort they could have been coaxed into outlasting diesel engine development. At the peak there would have been at least 50 of them running, but it was down to about a dozen when I started to use them in around 2003. This was at the European engine development centre for Ford.

[@Zeem4]

Would you happen to know if PDP-11s were used in the development of the lean-burn Valencia engine? I've got a 957cc unit on the floor in my garage, as a replacement for the one in my "stalled project" 1982 Fiesta that's sat next to it. If they were, it would be an interesting link between my two main hobbies of old cars and old computers.

[@andypughtube]

@@Zeem4 I would say, from the timeline, almost certainly. In fact the assembly line that they were built on was probably PDP-11 controlled too. I had a friend working at the Dagenham plant in the 1980s on PDP-11s on the production lines. (Blocks and heads were manufactured in Dagenham). The Dunton site (where the PDP-11 based dynos were) was built in 1966. It seems likely that the PDPs went in sometime before your engine was developed.

[@davethetaswegian]

I am looking forward to more videos on this system as I have very fond memories of the DEC computers. The first computer I ever used was a PDP-11/70 running RSTS/E in the mid 70s. The machine was installed at a college in the center of the city and connected to most of the local schools via dedicated phone lines (it would have had a whole lot of DB25s hanging out the back as well). The school I went to had a couple of ADM-3As at 300 baud and a TTY 33 at 110 baud.

[@alfred2406]

Yeah！ Long live the PDP11/70 on RSTS (for Resource Sharing Time Sharing？ I believe.). OMG, all bring me back to my early twenties.

[@ShulerBurton]

Awesome piece of equipment. I last used one in 1992. Rsts/e was o/s on an 11/84. Zork was on there as Dungeon! Enjoy! Learned pascal, Fortran and lisp on it oh and C. Thanks for the video. Used it for about 10 years.

[@wavefuse]

Acetone is one of my ‘go to’s for removing stick stuff, and it smells great too 🙂

[@tomdowling4810]

My favorite cleaner is gasoline. For many reasons a BIG No-No but it works.

[@glubone]

Use wd40 instead.

[@antonnym214]

Excelente! Thank you. This will be a lot of fun, just as the Centurion episodes are. Merry Christmas and all good wishes for 2023!

[@andycollins9080]

Looking forward to this one. I've been a bit of a PDP-11 fan for years. It's a great architecture and DEC kit is really screwed together well. Enjoy the journey 🙂

[@peterweingartner4364]

I am looking forward to this series. I have such a soft spot for these old DEC machines, and the PDP-11 was such an iconic computer.

[@mikafoxx2717]

If you keep buying minicomputers, you'll need to expand your room again!

[@KameraShy]

I give him six months.

[@lawrencedoliveiro9104]

I remember another channel from some years ago, called “jpkiwigeek”. He had a huge barn, full of Sun and SGI and other machines. His wife took one small corner for her scrapbooking hobby.

[@torbenolesen8560]

26:17 studying to be an engineer 1973 (assume it was this year), we had a PDP11 installed. This supplyed the existing system wih a hole card driven computer, which only was accessable from eletrical engineer studying. I was at the mechanicle study. The PDP11 was very simple. To start it up, you had to load a binary sequence via a swich panel at the front. The interface was a teletype writer/printer and the storage was via a paper hole puncher, also widely used at i.e. numerical controlled milling and cutting machines. The language was Basic. I was the one using it the most, and my final project was to make it possible to program a hydraulic 2 axis robot for heavy lift use, which also was part of projects for others. The hydraulic valves was analog 1-10V controlled and the movements was stored at an ordinary tape recorder via voltage to frequency converter. My project then was to convert the binary outputs from the PDP 11 to 0-10V signals. This ended up with being more a eletronic project than mechanicle, so in the end I had to change the project at another direction. But ithis was the start of what should be my employment for several years later.

[@skeezixcodejedi]

You're doing epic work .. who has space for the old project, let alone a PDP! Love it! You going to try and read the Maxtor and/or tape drive on something else.. like a PC?

[@orinokonx01]

I'm going to presume here that the hard drive is a MFM drive, with the typical 34 pin + 20 pin connectors. If so, I highly recommend the MFM hard drive emulation board by David Gesswein. I would link his website here, but youtube hates links. I built one of these boards to preserve the contents of a hard drive in an Intel System 310, and now that I have the drive image I can then use the same device to emulate the original drive (it even takes into consideration the type of hard drive controller!). Looking forward to this series! Happy holidays and happy new year to you!

[@richardlincoln886]

WD40 generally is a good non-destructive for glue / tape residue - if you can get it to the glue itself. Also saw Linus of LTT use hand sanitiser recently which randomly may work?

[@hessex1899]

We had several PDP-11's in our hackerspace back in the day. You will absolutely enjoy that system.

[@hessex1899]

I bet carbon tet would get that goo off, but it's carbon tet. :)

[@idahofur]

What kind of stuff did you do on them?

[@hessex1899]

@@idahofur Messed around with the various OSes and learned the hardware while getting them running. Basically the same thing he's doing.

[@georgegonzalez2476]

That’s an awful lot of steel and pleather! DEC was more centered on mini-mainframes where the customers expected big and heavy boxes. In this case, a bit of overkill to hold a 15 MHz CPU with a maximum of 256K of memory. The PDP-11 has a very clean instruction set but also micro programmed and very slow. It also had like a dozen operating systems, most of them lame. I programmed one for many years and was never amazed by its speed. Even tight assembly-language loops ran considerably slower than similar loops on a cheaper and much older PDP-8. I hope you can get yours running. Expect trouble with the fan and disk drive motors. The foam blocks may be necessary to keep one’s sanity.

[@markcummins6571]

this system supported a 4MB memory configuration and was not slow at that time.

[@georgegonzalez2476]

@@markcummins6571 Not that it matters, but it still only had a 16-bit address bus so you could only have 48K of code, 48K of data, and 48K of stack, in any one program. Instruction times were in the 20 to 50 clock cycle range, you could usually get more work done on a 1MHz PDP-8.

[@markcummins6571]

@@georgegonzalez2476 There is memory management on both machines. You code in relocatable code on PDP11's and an Operating System can utilize 4MB of memory (21 bits of address I believe). You do realize that the PDP8 memory page is only 4K in size and the breath of its code is geared to run fast but it does not have the power of the PDP11 opcodes. The PDP11 MOV code was usually be done in 6 cycles. I do not agree with your perceived average clock cycle utilization between both system types.

[@georgegonzalez2476]

@@markcummins6571 You are correct, the PDP-8 made you turn somersaults to access more than 4K words. But for small real-time tasks it was often faster than the 11! Quite a letdown when our lab got a PDP-11/34 and it didn't impress. The cycle counts I got from the long 11/40 manual. it took from 1 to 3 microseconds to fetch an operand, 1 to 6 to do the operation, and another 1 to 3 to store the results. Often adding up to being slower than a PDP-8! Adding insult to injury the baseline FORTRAN compiler generated "Threaded code". A really innovative and mesmerizing technique, but really slow as operands couldn't live in registers and each sub-instruction ended with a slow indirect and incrementing jump and no possible optimization. All three of us programmers there voted with our feet and did as much as possible on the faster and friendlier PDP-8.

[@markcummins6571]

@@georgegonzalez2476 The PDP8 machines, all of them were state level logic, not micro sequenced. It was a 12 bit machine. Only people that solve their small programing needs liked it. I do not believe that you lived in the PDP-11 world very much. Did you really quote 11 /40 cycle times to your 11/34 exposure, and decide the PDP-8 family was a better machine type than the 11 family, when it never took longer than one clock cycle to fetch an opcode, or writing to memory? Why would you want to execute an opcode from a general purpose register? How would you manage program flow? I do not believe you understand the PDP-11 programing systems so I do not think you could properly compare the programing environments of the two machines to compare which is better. You think that OS8 is better that RT11, RSTS, or RSX? If you three left, via feet, I wonder if the company was not better off. Please stop trying to rewrite history