Vacuum Tube Calculator Schematic

I have, or at least had, the '70s version. Good text; used it in EE379/380 at UIUC.

Well, I didn't come up with Moore's law :-). The thought of graphing a physical quantity vs time on log graph paper is pretty fundamental to a lot of science and engineering, and in fact quite a bit more primitive than showing how two physical variables (neither time) are related to each other. But you'll have to find some quantities you can measure and/or quantify (cost; heat and power; speed; some product of them; etc.) and show that they follow a straight line or a curved line or some kind of line on your plot.

Hint: One or two generations of technology on the plot do not do a very good job of convincing someone that there really is a well- defined curve. It's like plotting the sale of disco records in 1975, the sale of disco records in 1976, and assuming that they'll keep on selling more and more indefinitely into the future. It's much more convincing if you have many points and they span an appreciable amount of time and there are points spread in between the extremes.

Really, really think hard about making and measuring simple samples of different technologies doing similar things - maybe just one-bit adders, maybe counters, etc. - and showing 4, 5, 6 implementations over different technologies and time. This will be far more impressive than a single implementation that does something fancy. Measuring something or multiple things is very very very important.

A comment you made to someone else is quite wrong. Discrete transistors in RTL circuits are a quite different technology than TTL or CMOS. The active pull-up makes all the difference in the world in terms of noise immunity and speed for a given power consumption. You will note that speed, power consumption, etc. are all good things I'm suggesting you consider graphing.

If you can have your presentation be some "eye candy" - here is where sequential circuits really shine - then this will help a bit in attracting attention (ego boost for being popular at the science fair!) and will be a slight increase in your score. It is essential for your score that you concentrate on showing, say, speed or power consumption for each example as something that is very quantifiable for a good score. Do not neglect the posterboard presentation, that counts for a lot in the judging.

Too bad you ripped up your tube decade counters, I think that would've been ideal. You could put them back together :-).

Tim.

I always liked disco ;-)

...Jim Thompson

You like 'drag racing', too.

Nah, he kept getting his heels caught. ;-)

Are they too high, or too low?

I didn't peek.

The Obstinate Bitter Donkey part of me , still disagrees with not trying something to speed things up. If you want to strictly graph performance you can look that up, and no reason to build anything. So do toy with some variables and component changes.

The reason I pointed you to the neons is valid, try replacing your incandescent readouts with neon, then led, if they are in the anode circuit. Also on the link to the book with the dekatrons, is the GE guide to neon lamps, there is a neon memory cell there, and a neon counter, and a neon flip-flop, you might want to figure it in. Since hollow state is a power hog and bulky, and generates a lot of heat, designers would use simple components such as neons and photocells to reduce cost and add functions.

The ANITA desktop calculator used cold cathode, for example

One unit you might want to look up is the Atanasoff-Berry Machine of

Also Konrad Zuse and the K series.

And Eniac Whirlwind the Selectron tube.

What Ifs are a valid point in your presentation, if you can prove them , ie "If so and so had changed this component to this, and it sped it up xx percent..." It adds to your presentation.

Good, you have a fast enough scope. Be careful to stay within its max input rating in terms of voltage.

Now you need to find a mentor to review your work.

Also find a well stocked technical library and find a OLD version of " Ready Reference" by John Markus, it is a collection of circuits popular in the year that the book was published. In a chapter labeled "computer circuits" or "logic circuits", you'll find some more examples of tube computer circuits.

I'll scan in some diagrams from mine in a day or two, I'll need to talk my former ISP into giving me some space.

Lets talk methodology, how are you going to measure performance?

I like the Moore's law over a historical time.

Steve :bitter and grumpy" Roberts

I have had that book as well; do not remember if i still have it. A classic!

He is looking for a *digital* computer, and it does not have to be complicated or work with a lot of digits. So..under 100 tubes, obviously diode logic will be required. .

Wikipedia states "The Colossus machines were ... the world's first programmable, digital, electronic, computing devices. They used vacuum tubes (thermionic valves) to perform the calculations."

Note the words *DIGITAL ... COMPUTING DEVICES* in there!

I visited Bletchley Park some years ago, and saw the Colossus project in its early stages. They started by replicating one 19" rack and, IIRC, were using vertical chassis modules perhaps 4U high. These used Octal valves, remember, so we're not talking any kind of miniaturisation here!

Presumably they were able to test each module independently after they'd built it and one module or two may suit the OP's needs. (I wasn't REALLY suggesting he'd want to build the whole machine!)

The OP was particularly insistent on needing detailed schematics - and these most definitely exist for Colossus!

Could be worth contacting the NMOC to suggest exactly what he has in mind - or perhaps they might be able to suggest what sort of thing he could do with an existing module of a combination of modules as a stand-alone unit?

Terry

If you put all the stray capacitances in a well-calibrated SPICE model, you can come pretty close to real life.

The gotcha is that you have to know all the stray capacitances and have a well-calibrated SPICE model.

The less evolved designs could be improved... but the more evolved tube logic designs are very much tuned to the edge of practicality. Look at the different speed grades of the HP AC-4 and how they have tweaked each and every speedup capacitor in each flip-flop. The design is actually quite a bit more evolved for manufacturability and repeatability than many transistor designs.

Tim.

When I was in high school I constructed a half-adder out of hand-made relays. I had paper plans to build a simple logic game device using them, but soon realized I would not be able to afford all the batteries needed to supply current to the relay coils.

I occasionally still have fun dusting Beamers and Mustangs with my Q45 ;-)

...Jim Thompson

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If we knew what we were doing, it wouldn't be called research... -- Albert Einstein

Not exactly what you described, but here are some examples I used in a memo a while back:

I don't blame you for that. You could have been hurt, really bad. ;-)

--

aioe.org, Goggle Groups, and Web TV users must request to be white listed, or I will not see your messages.

If you have broadband, your ISP may have a NNTP news server included in your account:

There are two kinds of people on this earth: The crazy, and the insane. The first sign of insanity is denying that you're crazy.

Beamers are always dusty. Their owners think they are too good to wash them. What can you say about any car starting with a 'Q'?

Jeez, I go to sleep, wake up, go to school, come back, and there's a bunch more messages.

Ok... But most of them are useless. Please stick to the topic. Useless messages are, to say the least, useless. To say the most, cr*p.

The important part is the "45", meaning 4.5 liter V-8 ;-)

...Jim Thompson