6 ms·
Really cool, but just to nitpick a bit not entirely correct in some ways. Logical systems still sell their NuVAX machines, see https://logical-co.com/product/n
by herio 5y ago
Really cool, but just to nitpick a bit not entirely correct in some ways.
Logical systems still sell their NuVAX machines, see https://logical-co.com/product/nuvax-4400-system/ https://logical-co.com/product/nuvax-4400-system/
They also do PDP/11 systems and hardware.
I think they might be built using an emulator on PC hardware with some interfacing hardware, but still I would call it a "new" VAX for most purposes.
- bencollier49 5y agoI suppose that means the author of the blog post potentially has a market for his FPGA implementation.
- rob74 5y agoI think getting VAX software to run on an FPGA board is the lesser problem - getting it to be 100% compatible so it can serve as a "slot-in" replacement for an existing VAX is probably a lot more difficult.
- chx 5y agoGE Canada has VAXen running their atomic plants and they are under contract to keep 'em running for a long time, 2035 or 2045. (Might be called BWXT today.)
- throw0101a 5y ago* https://www.theregister.com/2013/06/19/nuke_plants_to_keep_pdp11_until_2050/ https://www.theregister.com/2013/06/19/nuke_plants_to_keep_p...
- mrweasel 5y agoI would love to have some one write an article about how they even manages to do that. Are they real VAX servers or have they've been virtualized/emulated somewhere down the line.
- nickdothutton 5y agoMore than you would imagine.
- skissane 5y agoMelbourne (Australia)'s train signals used to be controlled by PDP-11s running Ericsson JZA715 train control software. They were replaced by Ospreys. An Osprey is actually a hardware PDP-11 CPU on an expansion card which plugs into an x86 PC bus. It uses an actual CPU not emulation because realtime applications like train control need to be 100% cycle accurate. (Originally they used actual PDP-11 CPU chips manufactured by DEC, later they switched to using FPGAs). It also has Unibus cards to do Unibus-ISA/EISA/PCI translation so it can integrate with the original peripherals. http://web.archive.org/web/20210126085900/https://www.equicon.de/images/Virtualisierung/LegacyTrainControlSystemStabilization.pdf http://web.archive.org/web/20210126085900/https://www.equico... http://www.strobedata.com/home/ospreyguide.html http://www.strobedata.com/home/ospreyguide.html
- VectorLock 5y agoWhy does train control need to be 100% cycle accurate? PDP-11s ran at what, 1.25Mhz? I'd think that a modern CPU software emulating a PDP-11 CPU could get to below those cycle times.
- bluGill 5y agoA few cache misses in a row, and some branches mispredicted and your modern CPU is slower than 1.25mhz. This almost never happens (CPUs are very good at this) but when it does things can get bad.
- jandrese 5y agoLets say the modern CPU gets itself really tied up in knots and is out of action for a staggering 10ms. During that time a speeding train doing 350kph travels not quite a meter. Do trains run such tight scheduling that this isn't sufficient time to cause delay on actuating a switching element and cause an accident?
- bluGill 5y agoI have no idea. If this is real time control that could mean you keep running the motors in the switch long enough to damage something. Or maybe you go past the end of travel switch signal without reading it, the switch turns off and you never stop... There are a lot of ways real time systems can fail. You are correct that 10ms is well within the margin of error for safety stopping a train, but it may be out of the margin for some subsystem in the control.
- rob74 5y agoFascinating... in the phrase "replaces the VAX chassis, CPU, memory, KWV11-C clock and mass storage", the clock being mentioned separately intrigued me, so i googled it. Turns out that only the clock was a whole board full of good old TI 74x TTL chips - and a "used but working" board goes for 345$ on eBay (https://www.ebay.de/itm/M4002-KWV11-C-MODULE-USED-AND-WORKING/161265624922 https://www.ebay.de/itm/M4002-KWV11-C-MODULE-USED-AND-WORKIN...)...
- TheOtherHobbes 5y agoCompared to x nm VLSI, TTL and ECL are ridiculously low density. And soooo sloooow. DEC were very pleased with themselves when they got to ~40VUPs in the later ECL models, but a full modern VLSI - not FPGA - implementation wouldn't break a sweat at 1000VUPs.
- dfox 5y agoWhat seems particularly interesting is that the board seems to really be just an RTC, yet does not have any obvious place for backup battery and has 10MHz oscillator on it.
- cbm-vic-20 5y agoThe first-gen PDP-11's CPU was just a couple of boards full of good old TTL chips.
- noneeeed 5y agoI remember reading an old paper on some funky experimentat user-interface that used a pair of PDP-11s (possibly, might have been event older) essentially wired together at the busses, with extra instructions added with new logic in TTL silicon, I think it was for doing the maths for the vector graphics. It was amazing the amount of hardware hackery that was necessary to build these experimental systems.
- Taniwha 5y agoActually I think those were Vaxen https://gunkies.org/wiki/VAX-11/780#Dual-CPU_experiment https://gunkies.org/wiki/VAX-11/780#Dual-CPU_experiment
- minimaul 5y agoDefinitely at least some software emulation on x86. The manual for that system shows a board name "PEAK876VL2" in a picture - that's an x86 board - but LGA1156, so old!
- p_l 5y agoNuVAX is based around software reimplementation of VAX cpu with special-purpose I/O system to reuse existing interfaces (important when you need to deal with custom interface cards, for example). Funnily enough, it appears that real vaxen ended up being produced for shorter time than PDP-10, despite efforts going as far as encasing last high-end PDP-10 prototype in concrete and dumping it in mill pond (or so the story goes), as known single-chip PDP-10 were produced at least as late as 2004, after last VAX rolled off production line.
- skissane 5y ago> as known single-chip PDP-10 were produced at least as late as 2004 Who was producing a PDP-10 in 2004? I'd love to know more about this.
- TheOtherHobbes 5y agoXKL's TOAD-2 is/was based on a single chip PDP-10. The hardware is used as a router, but supposedly if you ask it very nicely you can get it to run TOPS-20.
- lproven 5y agoYup, the XKL TOAD ("Ten On A Desk") and TOAD-2. https://en.wikipedia.org/wiki/XKL#TOAD-1 https://en.wikipedia.org/wiki/XKL#TOAD-1
- p_l 5y agoAt the time of TOAD-1, there were also still machines built based on SC design, for effectively singular consumer - Compuserve.
- jcurbo 5y agoAre there really PDP-11s out there still doing stuff? That is wild
- spfzero 5y agoThanks, didn't know about NuVAX. How old is that product? It seems like you could do much better than 70 VUPs today. Or 5 years ago, for that matter. I guess it is because everything is done in sw emulation?