the PDP-11 lives!

Excellent decision. No microsoft code will run on that platform. The world will sleep better. Art

The Therac-25 was controlled by a pdp-11 ;(

Cheers

Don't blame the getaway horse for the bank robbery!

--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com

Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation

So the thing in my shed is valuable spare parts for a nuclear plant, not old junque I'm dumb enough to pick up and take home with me? Gosh, where are the nuke plant boys looking for spare parts, I'll make them such a deal...unless it's an 8. I think it's an 11, but I haven't looked at in in a while. IIRC it ran RSX-11, which would seem to increase the odds that it's an 11, unless it doesn't. I have some 256Kb tape drives in a different shed. Yep, that's right, a whole 256K on a cute little computer cassette. In both cases I figured the power supply and case would be the parts worth the bother of dragging them home, but I could be talked into changing my mind for adequate nuke-plant money...

Long live RSTS/E and RSX-11M!

RSTS was wonderful. I timeshared about 20 users on a PDP11/45, and it ran for months at a stretch.

--

John Larkin Highland Technology Inc

Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

FWIW my late dad programmed a pdp11 in the mid-1970s. One of his old pdp11 manuals from 1975 still sets on my shelf as a keepsake. My Basic progamming class in engineering school used a teletype connected to a minicomputer. Although the setup probably offered an experience similar to a pdp11, my minicomputer was actually an HP, IIRC.

Well, software is one thing - hardware another. While there may be some good reasons to keep a PDP-11 from a software point of view, I wonder how you should be able to keep the hardware going. And while the software may be solid and safe, what does that help if the hardware is failing all the time.

I had once the "pleasure" of keeping a Nord-10

Klaus

keep the code, just run it under emulation, there's no shortage of PDP11 emulators.

I have a pile of memory boards made by National Semiconductor, but they may be for the VAX.

If the nuke plant doesn't want the racks, I could use another one. ;)

Cheers

Phil Hobbs

And you can save on lighting, as I am sure they glow in the dark !

One of my benches started its life as a PDP-8, in dual racks with a center spacer. It came out of a factory in Dayton. I bought it and a Bogen MX60 amp from a small surplus shop for $100 and sold the amp for $100 two days later. On top of that, the surplus shop owner gave me about 20 pounds of new tubes sockets. How's that for scrounging? :)

I paid $50 for a blue Tektronix rack about 25 years ago. It has that nice chrome plated casting that says Tektronix. :)

You beat me to it.

But I also know that some idiot 30 years ago designed security systems using wired sensors all over the plant, effectively turning the PDP-11 into the most expensive static and lightning collector to destroy circuit boards plugged into the PDP-11.

I built surge and transient suppression modules and they went into huge rack panels.

As a young man I was praised for doing "NASA quality soldering" thanks to my Dad's training.

The modules I built carefully passed every test, destructive simulated lightning, nondestructive, and in actual use.

But they hired people who came from fast assembly line environments. I thought of them as like trained chickens. All they could do is solder really fast. But the modules they turned out had a very high failure rate and it became disastrous.

The installers actually had to SNEAK whole rack panels out of the plant to replace and rebuild after serious electrical fires.

I had been hired as an associate engineer and was willing to help out by doing the lowly soldering job without complaint but when they tried to downgrade my job title from "associate engineer" to "technician" I found out when they asked me to sign some personnel paperwork listing a different job title than what I was hired as.

I pointed out to the very man who hired me that I was hired as an associate engineer and actually wanted the title.

He asked "Do you want to work here?".

I said "Not if you're going to pull that kind of crap."

I asked for my final paycheck and walked home.

Some coworker from there told me that I was lucky because some of the other employees at the end had to wait months to get their last paycheck.

The technology of the Transient/surge modules was good, with gas tubes, pico fuses, zeners and MOV's. The scope traces of nondestructive testing and the scope traces of the simulated lightning bolt destructive testing were amazing.

Copper wiring to each switch/sensor and expensive transient/surge protectors all over that star topology just to stop the interface board in the PDP-11 from getting zapped by static or lightning strays seems so very Rube Goldberg today.

They could use fiber optic cables right into a board in a modern PC running Linux, with or without emulating a PDP-11 or Vax.

Or maybe even two-way rotating code RF..

Then again it IS quasi-governmental.

This looks like something produced by former DEC people:

I don't think GE is actually using that ancient wire-wrapped kluge for the CPU.

If it doesn't sport a PDP-11/70 or PDP-11/45 front panel, it's not a PDP-11. I don't care about how good the emulation might be. I need lights and switches that work right. (Toggle in bootstraps, etc.) I also would need a working paper tape reader and punch. Would help immensely to also include an ASR-33 or KSR-35. These human interfaces are very important. But most especially the front panel. The rest may be negotiable. But not the front panel.

Jon

In America, obtaining vintage spare parts is often not an insurmountable problem:

It's like with cars. I once drove a guy to an auto parts dealer. Asked him for which vehicle he needed something. A 1950's Chevy. Asked him whether he called and ordered it. "Nope, they always have that stuff" ... and they did.

If you need semiconductors from the days of Methusaleh you can get them made:

For discontinued ICs this would be a source:

Hardware problems are usually easy to fix on such old machines if the board isn't potted (so you may not be able to do that on a PDP-11 from an oil rig, for example), as long as one can obtain the semiconductors that need to be replaced. It is pretty rare that a whole circuit board goes up in flames and becomes a total loss. If you'd look around my lab you'd see a few things here and there that are well over half a century old and work just fine. Usually things that are quite irreplaceable, like this:

Absolutely makes sense. It's only a matter of time before someone writes an IBM OS/3XX emulator for the PC. It seems reasonable that after three to five decades, the sunken costs of software applications custom developed for the IBM mainframe dwarf the cost of developing an emulator. And Big Blue whatever supercomputers aside, a modern server built on the PC architecture can probably give most of the Big Blue big iron a run for its money.

Wire-wrap? Interesting. This calls for another story about my late dad.

He took me to his office every once in a while. An isolated boring place. When he disappeared for a while, to attend a meeting or something, he left me to my own devices. Or, rather, he left me to *his* own devices. *His* Friden Model STW-10 Electro-Mechanical Calculator provided geek-style entertainment. Punch enough keys in the proper order and it played the Friden March:

Anyhow, the most interesting occupants in the whole building were the bearded guys in the basement, which housed the mainframes and minis. One day a bearded guy showed me a board pulled out of a computer that he was in the middle of programming by rearranging a tangled web of yellow wires on one of its sides. I didn't know the first thing about wire wrapping at the time.

You got me wondering now if the bearded guy was working on a pdp11 board.

That sounds a bit cruel. One of my jobs back in the day was keeping fabrication facilities fully stocked. Facilities located in the backwoods that surround St Louis. The actual manufacturing floor was a wide open affair, with row after row of tables. Six 6' foot tables placed end-to-end to create a 36' row. The place was crammed full of women. Women's small hands were prized because small hands were best suited to handle small electronic parts. Anyhow, the whole deal felt sort of like a backwoods bingo parlor. With circuit boards substituted for bingo cards.