Wednesday 19th June 2013 08:28 GMT
John Smith 19Gold badge
Coat
PDP 11 odds and ends.
The PDP 11 (like the PARC Alto) had a main processor built from standard 4 bit TTL "ALU" parts and their companion "register file." So 2nd, 3rd,4th sourced. I'm not sure how many mfg still list them on their available list in the old standard 0.1" pin spacing.

El Reg ran a story that Chorus (formerly British Steel) ran them for controlling all sorts of bits of their rolling mills but I can't recall if they are

I think the core role for this task is the refueling robots for the CANDU reactors. CANDU allows "on load" refuelling. The robots work in pairs locked onto each end of the pressurized pipes that carry the fuel and heavy water coolant/moderator. They then pressurize their internal storage areas, open the ends and one pushes new fuel bundles in while the other stores the old ones, before sealing the ends. However CANDU have been working on new designs with different fuel mixes (CANDU's special sauce (C Lewis Page) is that it's run with unenriched Uranium, which is much cheaper and does not need a bomb making enrichment facility) and new fuel bundle geometries, so time for a software upgrade.

And 128 users on a PDP 11/70. Certain customers ran bespoke OSes in the early 90s that could get 300+ when VMS could only support about less than 20 on the same spec.

Note for embedded use this is likely to be RSX rather than VMS, which also hosted the ICI developed RTL/2, which was partly what hosted the BBC CEEFAX service for decades.

Yes, it's an anorak.. //

Wednesday 19th June 2013 18:20 GMT
Jamie JonesSilver badge
Thumb Up
Who's laughing?
I feel much better knowing this.

What is the alternative? Buggy software written by the "'Have you tried switching it off and on again" generation? Wednesday 19th June 2013 20:24 GMT
bscottm
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Re: It just costs money
It's not the GHz clock cycle that is the problem. It's the smaller feature size of the transistors that increases the single event upset (SEU) rate. Yes, the two are inter-related, but one could conceivably build multi-core, chip symmetric multiprocessors based on the PDP-11 at today's feature sizes and not have GHz clock cycle times (and still end up with significant SEU rates.)

A couple of years ago, a NASA/JPL scientist pointed out that the alpha particles (helium nuclei) from lead solder were causing interesting issues with current x86_64 I/O pins -- radiation issues on commodity hardware. //

Wednesday 19th June 2013 07:32 GMT
Duncan Macdonald
RSX11M - Dave Cutler
Anyone who read the RSX11M sources (driver writers especially) realised that Dave Cutler was a very very good programmer long before he worked on VMS and later Windows NT. He managed to get a multiuser protected general purpose operating system to work with a minimum memory footprint of under 32kbytes on machines with about the same CPU power as the chip on a credit card. (A 96kByte PDP 11/40 (1/3 mip) with 2 RK05 disks (2.4Mbyte each) could support 2 concurrent programmers - a PDP 11/70 (1 mip) with 1Mbyte and 2 RM03 disk packs (65Mbyte each) could support 10 or more.) During the many years that the CEGB used PDP-11 computers with RSX11M, I did not hear of a single OS failure that was not caused by a hardware fault - I wish that current systems were as good. //

Wednesday 19th June 2013 17:23 GMT
MD Rackham
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Re: RSX11M - Dave Cutler
Of course, that was several years after there was a protected, multi-user timesharing system running on the PDP-8, TSS/8. And it would run in 8K of memory, although you had to spring for 12K for decent performance. Swapped off a fixed-head 256K word disk.

You PDP-11 kids get off my lawn! //

Wednesday 19th June 2013 15:28 GMT
Bastage
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Go
Re: there are alternatives
There is replacement hardware available. NuPDP replacment CPU's including QBUS support and peripheral cards. Also NuVAX for the new kids.

The Reviver boards for PDP-11 and HP1000.

The Osprey PDP-11 and Kestral HP1000 hardware from Strobe Data.

There are also the Stromasys/Charon software emulators VAX/AXP/HP3000. //

Go
Re: there are alternatives
@Peter Gathercole

There is already a well established PDP-11 project on OpenCores:

http://opencores.org/project,w11 //

PDP 11 odds and ends.
The PDP 11 (like the PARC Alto) had a main processor built from standard 4 bit TTL "ALU" parts and their companion "register file." So 2nd, 3rd,4th sourced. I'm not sure how many mfg still list them on their available list in the old standard 0.1" pin spacing.

El Reg ran a story that Chorus (formerly British Steel) ran them for controlling all sorts of bits of their rolling mills but I can't recall if they are

I think the core role for this task is the refueling robots for the CANDU reactors. CANDU allows "on load" refuelling. The robots work in pairs locked onto each end of the pressurized pipes that carry the fuel and heavy water coolant/moderator. They then pressurize their internal storage areas, open the ends and one pushes new fuel bundles in while the other stores the old ones, before sealing the ends. However CANDU have been working on new designs with different fuel mixes (CANDU's special sauce (C Lewis Page) is that it's run with unenriched Uranium, which is much cheaper and does not need a bomb making enrichment facility) and new fuel bundle geometries, so time for a software upgrade.

And 128 users on a PDP 11/70. Certain customers ran bespoke OSes in the early 90s that could get 300+ when VMS could only support about less than 20 on the same spec.

Note for embedded use this is likely to be RSX rather than VMS, which also hosted the ICI developed RTL/2, which was partly what hosted the BBC CEEFAX service for decades. //

Wednesday 19th June 2013 13:20 GMT
PhilBuk
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Happy
Re: PDP 11 odds and ends.
Most real-time systems stayed as PDP-11 when the industry realised that the interupt latency on VAX/VMS was too slow for a lot of applications. You could improve it with a ccustomised VMS kernel but, in most cases, it was cheaper to stick with the devil you knew. Similarly, a friend worked for a measuring company that were using embedded PDP-8 systems as controllers well into the end of the 90s. used to drive round with a clip-on PDP-8 front panel in the boot of his car.

Phil. //

Thursday 20th June 2013 08:25 GMT
FrankAlphaXII
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Re: PDP 11 odds and ends.
Its a certainly a CANDU reactor and its fuel bundle loader robots from what it looks like.

CANDU is a different type of reactor than what gets built most of the time, they can burn just about anything, from some unenriched uranium with some slightly enriched uranium at the same time, to thorium, to Mixed Oxide fuels partially from decommissioned nuclear weapons, to "fun" transuranic actinides and also (as a proliferation concern) some quite nasty fuel mixes which can breed massive (relatively speaking of course) amounts of Plutonium if the reactor isn't properly safeguarded. Thats where India and probably Pakistan bred most of their Special Materials.

And what's cool about this is if the PDP-11 is what GE is using in Canada for their loaders, then its probably what they're using in India, South Korea, Romania, Argentina and China as well, as they also have CANDU reactors or designs derived from CANDU. //