On Thu, Nov 27, 2014 at 01:17:52AM +0000, Rich Alderson wrote: I heard (from Don Lewine) that the flakiness of the 93L415 SRAMs led to the KS's only patent. Even supposedly working CRAM boards get parity errors often enough that it's worth having the front end stop everything to reload the CRAM from disk, and maybe the system will live through it. Wicked cool! Guess that machine has 11' lives. John Wilson (JOHNW at AI)

Rich, I briefly had it running on MIT-AI (the KS, not the KA) in 2009 on an RM03, but the CRAM died and we haven't had the cycles available to do something about that. It's on deck for next year. (Yes, MIT-AI. We purchased it from CZ, who rescued it from the AILab skip, then from the Symbolics skip, then eventually sold it on eBay when he had to. It still has the MIT de-acquisition sticker on the front panel. It's next to the Toad-1 in the computer room.) ... are I agree. As I noted in my response to John Wilson, I'm working on it. :-) I have a good RM03 and a good KS. Get me a pack with ITS on it and I'll work on it too :-) Mike On Thu, Nov 27, 2014 at 2:27 PM, Rich Alderson < RichA at livingcomputermuseum.org> wrote: > From: Noel Chiappa > Sent: Wednesday, November 26, 2014 4:43 PM > > >> From: Rich Alderson > > >> We have a non-running 1090 here at the museum > > > Oh, good, then you have a machine to run ITS on (along with ones for > WAITS > > and Tops-10! :-) > > Yes, we do, but not that one. "It's dim, Jed." > > > Just kidding (mostly); ITS did run on a KL (without hardware mods), but > I'm > > not sure which model it was; it was a pretty early one. > > ITS ran on exactly 1 KL, MIT-MC. It was a "Model A" system, probably a > KL10B > but I'd have to ask the owner. It's currently in storage in Sweden. > > > I know it had the external memory bus, and I _think_ it had the RH20s (I > > know it had RP's of some kind, I think MassBus, because one of them was > > dual-ported and the console 11 booted off of it, and I don't think it had > > whatever PDP-10 disk controller the KA's had). I guess it was a KL-B, > then? > > All KL10-based systems have RH20s. The front end 11/40 has an RH11, and > one > disk (at least) has to be dual-ported between the front end and the -10. > > > Whichever one it was, anyone who wanted to run ITS on a KL would > probably want > > the same model - I know ITS had custom microcode (in part to emulate the > MIT > > pager, which had a different page size from the BBN/DEC one, and also > because > > ITS used some custom instructions which had been added to the KA's), and > > although one could probably get that to run on a different model KL, it > might > > be (an unknown amount of) work. > > Yeah, I've thought about how much work it would be. I'd prefer to start > with > the MC system if I were going to run ITS on a KL. > > > are > > a few running on simulators, I'm not sure anyone has it running on real > > hardware. That would be Very Cool. > > I agree. As I noted in my response to John Wilson, I'm working on it. :-) > > Rich > > > Rich Alderson > Vintage Computing Sr. Systems Engineer > Living Computer Museum > 2245 1st Avenue S > Seattle, WA 98134 > > mailto:RichA at LivingComputerMuseum.org > > http://www.LivingComputerMuseum.org/ > -- http://www.corestore.org 'No greater love hath a man than he lay down his life for his brother. Not for millions, not for glory, not for fame. For one person, in the dark, where no one will ever know or see.'

On Wed, Nov 26, 2014 at 6:27 PM, Rich Alderson <RichA at livingcomputermuseum.org> wrote: All KL10s have RH20 internal channels except the KL10-A of the DECsystem-1080. The 1080 was intended as a drop-in replacement for a KA10 or KI10, so the system would already have external standalone RH10 channels. Similarly all KL10s have cache memory except the DECSYSTEM-2040. Cache modules could be added to the -2040 turning it into a -2050.

On Fri, Nov 28, 2014 at 1:14 PM, Rich Alderson <RichA at livingcomputermuseum.org> wrote: Great story! I've heard from a former field service engineer that some 2040 sites managed to buy cache modules as service spares, which was much less expensive than the official 2050 upgrade, and install them "when no one was looking". They had to either remove them before field service showed up, or have a field service engineer willing to look the other way. The other schenanigan he told me about was an educational institution that had multiple of the same model of PDP-11 systems. They kept only one of them on a service contract, and would have students do board-level fault isolation and swap all the failed modules into a single machine. They'd sometimes wait until that machine had quite a few faulty modules before calling for service, which made it extremely difficult for FS to fix it until they realized what was going on. FS responded by marking the CPU serial number on all the modules in that machine, so on future calls if the numbers didn't match, they wouldn't touch it. The client was told that if they wanted to do their own service they should not renew the service contract, and should just buy service spares themselves. (Apparently PDP-11 service spares were quite a bit easier to purchase than LCG spares.) My friend quit DEC when the position was changed from field service engineer to field service technician at some point in the early 1980s. Apparently at that point they only wanted trained monkeys that would follow a service flowchart, and not use their brains, and only wanted to pay commensurately. That was reportedly yet another factor in some PDP-10 customers seeking a different computer vendor rather than going with the official migration path to VAX.

On Fri, Nov 28, 2014 at 2:01 PM, Pontus Pihlgren <pontus at update.uu.se> wrote: In the telecom industry, that's known as a "forklift upgrade", and it's become a major selling point of equipment if it is claimed to be upgradeable without that. How well that really works is an open question: 1) The non-forklift upgrade sometimes involves replacing everything inside the box, so all that you're actually keeping is the chassis, backplane, and power supplies. Sometimes not even the backplane, if it can't support the necessary bandwidth for the upgrade. Sometimes not even the power supplies. 2) Even when the non-forklift upgrade doesn't require wholesale replacement of the guts of the box, sometimes the cost is still very close to the full replacement.