16 posts • joined 4 Sep 2009
A well researched summary
Best summary of the situation I've seen : http://freelance.halfacree.co.uk/2014/01/disharmony-at-bletchley-park/
BBC content was removed due a copyright issue. It's back now with just one "still frame" of a picture removed near the beginning of the piece.
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.
At least there is no mention of this being to do with "superfast broadband" in ElReg's coverage, unlike every other news site that doesn't understand the technology.
Even the wikipedia page on the "One per Desk" mentions that it was marketed in the UK by BT as the "TONTO".
Technology Dead End
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.
See http://www.tnmoc.org/explore/tunny-gallery for details of what is at the museum.
Re: Elliott 803, paper tape and teletype
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.
Rugby College of Engineering and Technology had an Elliott 803 delivered in 1962, so come and revive at least some of your memories. We don't have an authentic operator though !
Decatrons are "cold cathode" devices, so they produce very little heat (just like the orange neon indicators in mains switches).
Re: Bletchley Park is awesome.
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.
Re: Try log tables
The "order code" (and lots of other information) is available on the CCS pages ....
Re: The "The paper tape output " in the picture...
... is actually a modified Creed 7 teleprinter adapted to take 5 bit parallel rather than serial data.
Grumble grumble. People that can't tell their Creeds from their Fridens :-)
If you "pop along" now you won't be able to see Colossus as it is enclosed in a protective box while the building work goes on around it. The rest of TNMOC is open as normal.
CSIRAC, running ?
" When a first generation computer is already running in Australia.. http://museumvictoria.com.au/csirac/"
According to Wikipedia "The machine finally found a permanent home in the Melbourne Museum in 2000. It has not been operable since its shutdown, but many of the programs that ran on it have been preserved, and an emulator has been written for it. "
No mention of it working on the museum web site either....
Decatrons are valves and they are gas filled.
The glow is around the Anode not the Cathode.
While the only thing they can do is to count, they do hold state equiv. to 3.3 bits. The state can be examined by applying 10 count pulses an watching for the carry output. So if the 7th anode is glowing the carry will come after three pulses. After the carry has pulsed, start pulsing the decatron in the adder until all 10 pulses have been applied. The adder will have moved on 7 positions and may have generated a carry. This is roughly the way the Witch adds decimal numbers together.
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