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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment. |
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6th May 2004, 8:50 pm | #1 |
Hexode
Join Date: Apr 2003
Location: Higham-on-the-Hill, Leicestershire, UK.
Posts: 338
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Vacuum Tube Logic
Took a bit of deliberation, but I think this is an 'Everything Else' topic! (Prepare to tell me I'm wrong, and it should have gone in the 'Vintage Computers' section!)
This is one of my recurring thoughts in Digital Electronics Lectures and Revision. Were there ever Vacuum Tube implementations for the Boolean Logic functions (NOT, OR, AND, etc)? It is a thought that popps into my mind every so often. Someone better suited to all this digital stuff could work the circuits out I'm sure, but I would much rather be told it has been done for me If anyone knows if they exist, I would like to see some of the circuits. Or were all early valved computers analogue ones? Idle thoughts over, best get back to the real world! Sam
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Can he lead a Normal life, Doctor? No, he will be ... an Engineer. |
6th May 2004, 8:56 pm | #2 |
Retired Dormant Member
Join Date: Mar 2003
Location: Bishop's Waltham, Hants, UK.
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Re: Vacuum Tube Logic
Sam,
yes the logic functions were implemented with valves, as were registers and counters - you do sometimes come across them in old test equipment, especially teleprinter test gear. Also look at the input circuits of scope for multivibrators. Some of the counting circuits used special valves (dekatrons, for example), and a great deal of use was made of thyratrons (though only for very low speed stuff - they won't work reliably above about 15KHz, look at all the problems with early TV timebases!). There were also valve op-amps. I have some somewhere that use two double triodes, with the bases and associated components mounted on an octal plug. Jim. |
6th May 2004, 9:40 pm | #3 |
Retired Dormant Member
Join Date: Dec 2003
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Re: Vacuum Tube Logic
There were a number of digital computers made with valve logic. Starting with Colossus. Then ENIAC and EDSAC in the USA, various early machines in the UK. The early versions of the Leo made by the Lyons company, all the early IBM machines. Ferranti Pegasus.
I'm not an expert on the subject - these are the ones that come immediately to mind. There were probably more. Plus all the valve logic in TV studio equipment from the 1930s to the early 1960s. Used mainly for complex pulse generation. |
6th May 2004, 9:50 pm | #4 |
Retired Dormant Member
Join Date: Mar 2003
Location: Bishop's Waltham, Hants, UK.
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Re: Vacuum Tube Logic
you can try here for a valve based calculator (OK so there cold cathode thyratrons, but there still glass....)
http://www.oldcalculatormuseum.com/anitaC-VIII.html ther's lots of other interesting stuff on this site aswell. Jim. |
7th May 2004, 12:25 am | #5 |
Rest in Peace
Join Date: Apr 2003
Location: Edgware, North London.
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Re: Vacuum Tube Logic
Hi Sam
In 1962 I started working for Elliot Automation who had just ventured into solid state computers ( mainly germanium!) and as a result there were loads of scrap modules left lying around from their first generation machines, each module about A5 size with either 2 or 4 double triodes. As Jeffery pointed out there were others including the Ferranti Pegasus, one of which was installed in my old college (now City University). I was not involved with it , but I do remember venturing into the room out of curiosity & thinking " Its a bit warm in here! " Joe |
7th May 2004, 7:52 am | #6 |
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Re: Vacuum Tube Logic
The Pegasus was a very advanced design for its day. It did not need an air conditioned room because the cabinets themselves were cooled, albeit by external plant. Somebody I know did work for the ill starred Blue Streak missile on a Pegasus. He sometimes claims that it was his work that caused the project to fail
A few years ago I went to a meeting at the Science Museum where a Pegasus was due to be demonstrated. About 20 minutes before the demo the machine decided to give trouble |