Compuserve PDP-10 SC-40 Boot Up

Watch as Gerry explains the history behind this Compuserve PDP-10 computer, as well as shows you the Boot-Up process. Today computers a fraction of this size have more multitudes more processing power and storage, but in the '70s this machine was an industry standard. It was used by hundreds of programmers and operators and shares a bit of computer history.

[@BobRDeTamble]

I worked at ADP's Ann Arbor computing center where we were the other major PDP-KL10 center left on the planet. We used to share a little of the dinosaur technology back and forth with CompuServe trying to stretch the life of the systems while we tried to get the clients to move off onto more current hardware. I think CIS got some of our shared-memory technology and we started using their proprietary SCSI interface boards. It was such a dream being able to install the equivalent of an entire string of RP06 disk drives (the kind of things that looked like a row of washing machines in a laundromat) into a standard tall PC case and then put the whole thing right INSIDE the KL10. It was like installing a Chrysler Hemi in an old Stanley Steamer... but it worked just great. Our engineers worked with the SC team in Las Vegas when they were designing the SC-40 because we'd done a lot of work with them on our shared-memory hardware for the KL-10s. The news of the KL10 "clone" began to trickle down through the tech departments and the excitement when we got our first test system was like Elvis was visiting. It was pretty amazing watching that relatively little cabinet running our modified TOPS-10 system at EIGHT TIMES the speed of the standard KL10, using a fraction of the power and generating almost no heat or noise. We ended up replacing two gigantic computer rooms full of noisy, hot, huffing and puffing dinosaur KL10s with a row of quiet, cool and blazing fast SC-40s. I was pretty new to the job and in a way it was kind of sad that as one of the new guys I ended up decommissioning the KL10s and helping push them onto trucks to be taken down to Texas and melted down into hubcaps (or whatever). They ended up filling the former computer rooms with cubicles and people and PCs, and of course every person had a way more powerful computer on their desktop than the hardware that had been replaced. (Of course, they weren't trying to multitask hundreds of clients like the KL10s excelled at.) The SC-40s didn't last though... it wasn't long before they too took that long lonely ride down to Texas, replaced by VAXen at last. But they were an amazing footnote in computing history... and a testament that you can accomplish pretty much anything you put your mind to, no matter how small the niche you're trying to fill may be. Excellent video, by the way... almost brought a tear to my eye, seeing that run one more time.

[@tpcdude]

Bob, thanks for adding that bit of ADP SC40 history. We are currently listing the rest of the SC40's on Ebay maybe you want one, we cant keep them all. when you were working in a maching room with strings of RP06' with heads flying you really felt like you were doing something.

[@BobRDeTamble]

Gerry Moersdorf Lol.. a friend had an RP06 run over her foot when we were moving one into a string one time. Her toes were purple for a week... from being run over by a hard drive. I guess that's why they called it the "Big Iron". The real fun came when a DEC PDP10 KL10 CPU died and it took 4 of us to push the "spare" in from another room. I knew I'd hit the big-time when the place had a spare mainframe running hot and ready at a moment's notice..!

[@compu85]

+BobRDeTamble I worked in that data center too. It was a neat building. I always liked how they built it on the border between 2 power companies and had both servicing the facility.

[@BobRDeTamble]

Sorry... didn't notice the comment notification before... Yeah, I remember a number of times having two separate power feeds saved our bacon. Actually, both feeds were actively used normally, one feeding power to the older computer rooms and the other feeding the newer ones. In case one incoming feed died there was a relatively involved procedure to tie both feeds together so everything could be supplied by the one remaining working feed that used key activated (regular housekey looking keys) locks to unlock the circuit breakers so you couldn't accidentally tie both feeds together when both were active. They made the newbie hardware engineers practice it before they were allowed to be on duty on the weekends when they'd have to handle things all alone... I remember I only had to do that once and must have jumped 3 feet when the circuit breakers closed with a resounding "BANG!!!" It was kind of sad when the old dinosaur computers were all packed into trucks to be recycled into hubcaps and replaced by cubicles filled with PCs.

[@JimEbright]

I am happy this bit of history has been preserved. The PDP-10 started the Internet!

[@WizardOfCB]

By far the best SC-40 video ever done! No kidding, this is fabulous that you have preserved these amazing machines, and totally impressive that you have been able to boot them up. Stew Nelson & Mike Levitt are unappreciated true geniuses - they fled Silicon Valley for Reno (better tax climate), and designed the SC-40 chip with the Hitachi simulator - and got it perfect on the first try. The boards you show were actually manufactured by CompuServe under license from the SC-Group (formerly Systems Concepts).

[@jj74qformerlyjailbreak3]

I’d love to have anything PDP. My favorite Collection CPU J11. All the years I’ve seen these systems in the junk yard. I never thought to harvest anything I had access to. You learn from your mistakes. I’ve learned my lesson. Great video. God Bless.

[@AnonyDave]

I'm so glad this little bit of history has been stored on the internet, and then 9 years later the algorithm decided to show it to me. PDP10's are a little before my time, but thankfully did get to play around with them a little bit via simh

[@spedraja]

Very impressive. I was a Compuserve User by the end of the 80's until the massive use of Internet. I ever heard about the use of PDP-10s as background but this video is a great and concise lesson of Cmoputing History. Thank you very much for the effort in all aspects. You can have our support if you need it. Regards.

[@JasonStevens]

Interesting how this video is making the rounds... I wonder if they'll image the disks and give rise to a retro compuserve

[@SpringDivers]

I remember Aunt Nettie and all the System 10 documents. I was an instructor at the Western Electric training center in Dublin.

[@videooblivion]

Gerry, THANK YOU for saving these pieces of history from destruction!

[@tpcdude]

Thanks for the comment, sometime i think i am the only surviving PDP-10 fan left.

[@ASCIITerminal]

Thanks for showing this! I have been a huge fan of Digital since I started my career programming on a Vax 11 cluster. Many projects and a few companies later, I still do a little bit with Tru64 on Alpha but even that is going to die out very soon and then it will be goodbye DEC. Having said that, I never realised that CompuServe used the PDP10 so extensively!

[@DrayseSchneider]

I've got to admit, there's something really impressive about mainframes.

[@stargazer7644]

These are minicomputers, not mainframes. They came right before microcomputers.

[@ComputerHistoryArchivesProject]

Great video! Had never seen the insides of the Compuserve PDP-10. Very interesting explanations too, Thanks for doing this! ~

[@chrisyannella8682]

Wrote an application that would log into the Compuserve free-demo account and grab the weather forecast once an hour for my local bbs users. Same application would feed other local BBS's as well. All pre-internet. This is very cool you were able to save this hardware for history.

[@JanBruunAndersen]

Thank you for keeping history alive.

[@tpcdude]

Its a dirty job but someone has to keep our enginerd history out of the dumpster

[@jeandesrosiers5275]

Neat, I worked on KAs and KIs for DEC in Canada, we never had these clones or at least I never knew about them. Nice to preserve some of the old computers. Some may question the validity of saving working equipment, they are at least as important as any antique or vintage tool or vehicule.

[@Alpha8713]

Aside from the size, this stuff actually looks more modern than I would have expected. It even understands post-y2k dates.

[@johnclausen1562]

I hope you are able to recover some disk images of the original Compuserve. I would love to play with it on a PDP-10 emulator. I was a Compuserve user in the 80s. I loved it and nothing will ever take it's place. Long live the CB simulator!!! Thanks for saving this equipment, I always wondered what happened to it.

[@mercster]

CB changed my life! I was on channel 17 for teens :-)

[@hal970fx]

Beautiful machines, and I couldn't help but smile when I saw TECO in the command listing.

[@HereComesPopoBawa]

Great tour! Thanks for showing us around these interesting old systems.

[@pixelflow]

Wonderful presentation, cool to see transitional hardware like that.

[@CopperheadSysop]

This takes me back. I remember writing programs in Basic and Assembler. I even got my first exposure to Pascal or Modula/2 (I can't remember which because they were so similar)

[@rattytoon]

Brings back memories. Everything starting with Boot40 until OPSER started running was stuff I wrote. That one big chip (400 gates) replaced two boards in the SC30 and probably a half-dozen boards from DECs last effort (KL10). Stew could keep track of the whole thing in his head. I remember that someone asked for a change. Stew sat there for a few seconds and said sure, he could fit that in.

[@tpcdude]

Do you think Stew has seen the videos? he seems to be off the grid.

[@AguyNamedHorse]

Wow, its awesome youre able to still get this running, great vid

[@mercster]

SO awesome. Thanks for keeping that running.

[@mercster]

Hey, that's FOOTY (FDDI) to you! :-)

[@mercster]

CompuServe was my first online experience, such fond memories.

[@mercster]

Hah, boots pretty fast actually... as a UNIX admin I'm used to large machines taking 30 minutes to boot.

[@mercster]

I can smell the iron from here...

[@mercster]

ROFL... I just went to subscribe to this channel, and I already am. Musta been years ago, I don't even know when or why I subscribed!! :)

[@Cheap_Skate]

The chip at 10:30 is a Fujitsu MB86930-30 SPARClite processor. Thanks for the great video and for sharing such an awesome machine!

[@tpcdude]

That makes sense since the masked part that forms the pdp10 cpu is fujitsu and development software ran on a Sun workstation.

[@pereimar]

Awesome! Thanks for sharing this!

[@douro20]

The supervisor processor is a SPARC, specifically a Fujitsu MB86930 SPARClite which was the first SPARC processor specifically designed for embedded applications. According to System Concepts, the whole system, other than the custom CPU, is built up from commodity chips.

[@tpcdude]

Thanks for the data on supervisor CPU chip, this makes sense since the system was built using sun workstations for gate array mask development and simulation.

[@timothystark4475]

Impressive! I was CompuServe member some time ago.

[@tpcdude]

Regarding some of the questions below, I am preparing a number of the SC40 systems to donate to "the living computer museum" in Seattle funded in part by Paul Allen of Microsoft fame. I am trying to figure out how to load the stock DEC monitor on the system. Since there are many revisions of the SC40 micro code and no way to boot the distribution mag tapes the process will have to involve another computer with internet access and SCSI disk support and who knows what else. The systems concepts founders seem to gone off the grid and they took the secret decoder ring with them. Long live PDP-10 hackers.

[@TheReimecker]

Awesome Video !!

[@tpcdude]

Closed for lockdown now but visit the living computer museum in Seattle

[@dextardextar]

also that dude's smoking a blunt at that desk, lol dank.

[@Joeyboots80]

I love stuff like this! Great video! Fascinating!

[@WHValenti]

I thought your name sounded familiar! I was on OSU's IRCC-CIS KA-10 serial# 76 at the same time as you. My wife was one of the operators. I went to work for DEC shortly after the KL was brought in to replace the KA. We both consulted for CompuServe over the years. It was a dark day when Jupiter was cancelled, and really nice that SC and Foonley picked up where DEC left off. I still have shelves of documentation from that era, and a working LA36 that might make a good serial console if you need one.

[@tpcdude]

+Bill Valentine-Cooper Well hello blast from the past. I came to OSU in1970 and dropped out in 1973 or so, I lived in Caldwell lab KA-10 computer room and worked for Tom Defanti, who got his PHD and later wrote code on the pdp11/45 for Tom and Chuck Csuri on an animation system called "Grass". I self taught myself by reading the Tops10 4.N.72 monitor code, didn't go to classes and it all came out good in the end.

[@WHValenti]

+Gerry Moersdorf , OK, so I guess we didn't quite overlap, because I came to OSU in 1975, and left in 1980. I had the office closest to the lab, right next to the SW stairwell, like, 408 or some such. We used to climb out the windows and sit on lawn chairs on the roof. Herb Johnson was managing the operators, and the one who'd been around the longest was Jim Davenport. He got my wife Susan hired there, and then his wife Laura introduced me to her. I was working on a project on the DEC10 for Dr. Lee J White, who was acting CIS chair, Dr. Chandrasekaren and Dr. Zweben. I seem to remember the DEC FS guys as being Fred Saas, Dennis Slagy and Del Waggoner. When I started at DEC, the TOPS old-timers were Dave Len and Dave Gorka -- ring any more bells?

[@tpcdude]

+Bill Valentine-Cooper I do remember some of those names, what a blast from the past, Chandra was Tom's Professor and I met him a few times, but I do remember the little box offices with the roof tanning booth. They paid me to teach pdp10 Assembler to PHD candidates, and I was a drop-out, I guess OSU didn't really believe in their product. I have a picture taken in the men's room where we dragged a TTY33 into the stall and you could see legs of Tom Defanti at the base of the teletype with him sitting on the throne and the teletype paper coming off the back. its one of my treasured photos of the time.

[@dv_vid]

My first e-mail address was with compuserve back in 1995 when I was 17. GO CB to take you to the CB Simulator. My user id was 103512,1543. CompuServe - the information service you won't outgrow! LOL. Had to be careful not go go into the $ services like InfoTrak. I still have a working copy of DOSCIM.

[@Cimbolic]

Beautiful!

[@richardclarke376]

@Gary I'd love to come and check out that equipment

[@klankab]

Hi Gerry. It's great that you made the effort to save these machines! What will happen to them now?

[@capnrob97]

Nice. My online experience back in those days was "The Source" on an Apple II with a 300 baud modem.

[@drjonathanhaverkampf7704]

Thank you for the video. Great!

[@tpcdude]

There is a second video "systems concepts sc40 pdp10: operation demonstration" that describes the startup for the system sent to the "living computer museum" in Seattle.

[@youreale]

wow, nice stuff there

[@TheReimecker]

I wish i could see some of this PDP's in real live.

[@cosimoto1]

I used to run my XRF Spectrometer with a PDP-11. That machine cost $30,000! In the end they gave it to me and I, in the end threw it in the trash! Sort of wish I had kept it now!

[@mercster]

HOLY SHIT, I got to the end of the video and you're into RADIO TOO?!?! HAHA, you're awesome sir. I've been trying to dip my toes into shortwave for the past few years, but I can never get a decent antenna up. Sub'd!

[@paulgalbraith2038]

Now if you can dig up the old source code for Island of Kesmai, let me know!

[@mercster]

My first "online" experience was CompuServe. (Along with some local BBS).

[@moviestudioland]

It is really cool to see this PDP-10 boot up. I used to use a PDP-10 at the University of Pittsburgh which had two of them as a student. I found out that a simulator was built for the DEC equipment and was able to get a Phi Wherry image running on a simh simulator. I have this running on Amazon AWS and have been able to run the TOPS-10 OS on a Rasberry PI single core computer too. To try the TOPS-10 just issue this command from linux or even windows dos prompt: telnet jeffreyfall.com 2020 and you will get a prompt of . then do a systat or a sys and you'll see the status of TOPS-10. There is also VMS 7.3 running on a Rasberry PI at telnet lgcrc.jeffreyfall.com 6000 Of course this is no way as fun as handling and booting the real hardware.

[@jayfarrell4708]

In the mid-1970s I did freelance tutoring for students at Pitt and got to play with the DEC 10 computers remotely. The actual mainframes were located at the RIDC Industrial Park in Blawnox and accessed via RJE terminals in the basement level of the Cathedral of Learning via a microwave link. They had keypunch machines and card readers for program input, as well as big, noisy line printers for output.

[@dextardextar]

this baby can hold so many webrings

[@MultiShawnt]

Excellent! ,,,

[@aaroncastro910]

Interesting...

[@lawrencedoliveiro9104]

Hey, I have the exact same Thermaltake case. :)

[@Jormunguandr]

Nice!!! :D

[@BobDarlington]

Is that a big AM transmitter against the wall? Pushing BC610 mass! T368 maybe?

[@tpcdude]

Good eye! that is a T386E/URT to see more AM transmitters go to QRZ and lookup my callsign KC8ZUL

[@WarrenPostma]

So the PDP-10 CPU is emulated in a Gate Array (FPGA)? What was the main clock speed?

[@tpcdude]

+Warren Postma The clock speed was software selectable from the MSP ( the bootstrap processor) the speed usually selected at CompuServe was 33MHZ

[@warp9988]

+Gerry Moersdorf Cool thanks! As someone who used CompuServe briefly in the 80s and the early 90s, before "The Internet" was being used by ordinary non-DARPA/non-University people it was really The Online Hub. There was a commodore forum on there, and a bunch of other message boards and it was quite the thing back in the day. I had to pay to access Telenet or Tymnet and then pay for CompuServe so it was not cheap.

[@jholttn]

I thought you might find this slightly interesting. When I worked for Kroger in the 90s I worked in Customer Service. We had Western Union just like most Grocery stores do today. I noticed that the number for the Western Union computer that it dialed was the same tel# that I used at home to dial-up for Compuserve. I still remember my username for Compuserve. 71162,1676 or e-mail was 71162.1676 of course. See if you see my old account in there if you've gotten that far by now. lol

[@tpcdude]

Thanks for the story. Compuserv hosted many services and not surprised WU was one of them. They zapped the customer files before they retired the SC40's

[@SHONNER]

TOPS 10. Good stuff.

[@batlin]

It didn't seem to have a problem with the post-Y2K date?

[@thecooldude9999]

Nope. These were in commercial operation until quite recently.

[@Wizardofgosz]

Hey Gerry, is the Compuserve application or source code still kicking around on any of the SCSI drives

[@tpcdude]

Not the source, just the compiled/assembled stuff. that's what i have on my SC-40 and the one at the Living Computer Museum. However old it is I don't think AOL/Compuserve wanted anyone to have that. They use it to defend patent infringement actions.

[@Wizardofgosz]

I bet there would be a lot of people who would like to experience C-Serve again. It's too bad they wouldn't allow it to be put online, again, in one form or another. I used The Source briefly in the 80s at a friends house, and then Quantum Link on one of my commodores. I never got to experience CServe and their cool Octal usernames! I was running a BBS this whole time. Then the next think ya knew it was 1994 and there were local ISPs offering dialup PPP accounts.

[@stupossibleify]

was there really one modern card per active user?

[@tpcdude]

+stupossibleify that depended on modem speed, but the compuserve net had at most 4 modems per module

[@igfoobar]

Ah ... I miss real computers.

[@zaprodk]

Fix the title :D

[@mercster]

GREP

[@mercster]

Please hire me at minimum wage to run this shit.

[@thelavian4481]

So you can afford all this great gear, but you can't afford a tripod?