Not quite what I said....
At TNMOC we use a Pi to run an emulation of the 2966 when the real machine is not in operation, but the real 2966 uses an SD card for it's mass storage as we don't run any of the real disk drives for environmental reasons.
52 publicly visible posts • joined 4 Sep 2009
I know you shouldn't speak ill of the dead, but according to the former Elliott employees I've spoken to, Iann Barron did not design the Elliott 803. He may have had a minor role, but that's all.
In Simon Lavington's book "Moving Targets Elliott-Automation and the Dawn of the Computer Age in Britain, 1947 – 67" page 352 it says
"Iann Barron was involved as a Vac student but played no part in the real design [of the 803]"
The design team was John Bunt, Jim Barrow, Laurie Bental, Roger Cook.
I have Laurie Bental's original hand drawn logic diagrams from when he redesigned the 803A into the 803B!
Elliott 803 Curator
The National Museum of Computing.
One of the popular design of high speed paper tape readers was based on a design from Cambridge University. I think it was originally an EDSAC II peripheral. It uses a continuously rotating capstan above the tape, a free clutch roller under the tape, and a brake pad to stop the tape on a single character even when going at full speed. The clutch and brake are both operated by solenoids. The maximum speeds were 250/500/1000 cps. The 250 cps versions didn't have a brake and relied on tape friction to stop the tape.
Anyway, the design was licensed to Elliotts, and it appeared on their own 800s/900s/500s/4100s and also later ICL 1900 machines. We have examples at TNMOC fitted to Elliott 803 and 903, and also the Marconi TAC.
Here is the 500 cps version on our Elliott 803.
An example of a variation on the same theme is the Trend UDR 350.
The Elliott 803 Algol Compiler only produced numeric error codes which had to be looked up on the manual.
My favorite one is "Error 49 : Program too large to complex to be compiled at all".
These days there would be an emoji at the end rather than the added "at all" for extra emphasis!
If you do ever get over here please get in touch as I'm not at the museum every day so we would need to coordinate if you want to see the 803 in all its glory !
I have in fact just upgraded the LED display to us a Pi PICO rather than a PIC thus putting another generation between it and the 803 !
You are welcome to visit to come and see why I use a modern DSO to diagnose faults ! I'm not sure I could have kept the machine working this long if I had to use an analogue (non-storage) 'scope. I can see no point in making the job harder than it has to be !
Did you notice the board behind the 'scope that has two rows of 48 LEDs ? It captures and displays one word time's worth of bits from two signals. It is mostly used to capture, hold and display the last value read from the core stores when a parity error occurs. The store test programs write a pattern of all ones or all zeros into memory locations, so the board makes identifying the faulty bit much easier.
I have great deal of admiration for the field service engineers who fixed these machines for real in the 1960s. Luckily I was able to learn from one of them when we did the original restoration work nearly 30 years ago.
They are signals within the core store read amplifiers. To be honest I'm really not sure how they manage to detect the difference between a "1" and a "0". But they do, and they get it right nearly all of the time.
The 803 is a serial machine, so it's all about "pulse" or "no pulse" for ones and zeros, not "high" or "low" voltages.
You are not just watching a pre-recorded video. Every tour is different. We have multiple tour guides and each has their own style. Also we can tailor tours in terms of duration and content to meet specific groups requirements. And how would you ask questions of the guide on a pre-recorded tour ?
Please don't mix up "The computing museum part " (properly called The National Museum of Computing" or TNMOC for short) with the Bletchley Park Trust (BPT) . They are two separate organisations, with TNMOC paying rent for their buildings to BPT. TNMOC is facing the same lack of income from visitors as BPT but it makes more use of volunteers for it's operations. The volunteers have been working hard during the closure to make it as safe as possible for reopening (and to do lots of redecoration).
TNMOC has been regularly putting "#AskTheExperts" interviews on it's YouTube channel while it has been closed, the latest going up only 4 days ago (so not sure where you got 4 months from).
The Algol Plotter Package (Library Tape P104) was a precompiled tape which contained the output of pass one of the compiler (called Own Code) and various bits of compiler state. It was a binary dump of the Own Code so loaded faster than running pass one on the corresponding source code. Your source was then read in and its Own Code appended that already in store. Pass two then read the combined Own Code to produce the executable in core.
Back in the days of BSD4.3 Unix I was a post-grad student and I built a kernel for a VAX11/750 to try and debug poor NFS performance between the VAX and a IBM PC/AT that had an Enthernet card and ran NFS client software. Several years after I had graduated I got an email from the then sysadmin asking if I knew anything about all the debuging messages with my user name in them that had appeared on the console printer overnight ? And yes it was a proper printing terminal.
Seems my kernel had never been replaced with the original after I fixed the NFS issue in the PC software !
Just to clear up some misunderstandings. You are (and will) will still be able to view Colossus by visiting The National Museum of Computing rather than the Bletchley Park trust's site. Colossus gallery is open every day, the rest of TNMOC is open Thursday,Saturday and Sunday afternoons.
See http://www.tnmoc.org/visit for full details.
In the 1950s and 1960s Elliott Bros. used what was called "Magnetic Film" for the backing store on their 405 and 803 computers.
An 803 with three film handlers is shown here:
Operating handlers are show in the segment between 1:10 and 1:30 in this Pathe news reel:
Optional mass storage is available on an unusual magnetic tape system based on standard 35 mm film stock coated with iron oxide (manufactured by Kodak). At the time this was in use by the film industry to record sound tracks. Elliott's factory at Borehamwood was close to the Elstree film studios which explains the use of the 35mm sprocketed media. The 1000 foot reels held 4096 blocks of 64 words per block (4096 x 64 x 39 = 10,223,616 bits, or the equivalent of about 1.27Mbytes).
Although we have a Film Handler in good condition at The National Museum of Computing we don't have the cabinet full of logic boards (called the "Film Controler") needed to interface the handler to the 803 CPU.
Hi Chris! Sadly some of the details of the Elliott machines got a bit mixed up by El Reg's Journo ! Probably they were too excited by it all :-) I would trust your memory. There is a picture of the 803 in P4 hanging on the wall behind the 803 at TNMOC. Only yesterday I was running some HCODE programmes on the 803.
If all you want to do is visit the "geek-gasam inducing collection of computers", then you don't want to visit the Bletchley Park Trust as such as their tours cover the war time story (intersting as it is) but don't even include a visit to Colossus any more. What you want to do is visit "The National Museum of Computing" which is a separate museum located on the BP site.