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Old 24th Nov 2020, 6:08 pm   #61
greenstar
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Default Re: Would we have got to the moon with no semiconductors?

"Yes, in the vaccuum of space, but not in a spacecraft that contains air.
Also, exposed valves without a glass envelope would I suspect interfere with each other. How do you stop electrons emmited from the heater of one valve from landing on the anode of a different valve, or indeed on any other exposed conductive part that is positive with respect to the valve heater".

Would this be solved by screening? Perhaps minute valves could be printed with some sort of enclosure, and the whole unit evacuated. It wouldn't need to be a heavy case if it was open to space. Maybe making more sense if manufactured in space!
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Old 24th Nov 2020, 6:38 pm   #62
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Default Re: Would we have got to the moon with no semiconductors?

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With micromechanics and nanotechnology I'm fairly certain a 'valve' computer comparable to what Apollo used could be built, if the will was there to do it.
... and operate it flying to the moon and back ?

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Old 24th Nov 2020, 6:49 pm   #63
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Default Re: Would we have got to the moon with no semiconductors?

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Originally Posted by merlinmaxwell View Post

Using valves would only be a matter of size and power consumption no matter how impractical. I am glad to have started this thread, very interesting.
So am I! Thanks for starting it, I'm following with great interest.
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Old 24th Nov 2020, 8:40 pm   #64
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Default Re: Would we have got to the moon with no semiconductors?

Look at it the other way round. How do you get something of that weight into orbit, let alone to the moon and back. Scaling up launch vehicles must be as big a challenge.
Theoretically possible using valves, but as impractical as was the valve CD player mooted recently.
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Old 24th Nov 2020, 9:21 pm   #65
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Default Re: Would we have got to the moon with no semiconductors?

Maybe in parts, assembling them in an orbit around earth? There were scenario's like that developed already in the 60's for the period after the Apollo program (target: Mars).
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Old 24th Nov 2020, 9:57 pm   #66
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Default Re: Would we have got to the moon with no semiconductors?

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Originally Posted by Radio Wrangler View Post
As said earlier up the thread (MM) there is no 'PNP' valve, maybe P channel would be a better way of phrasing it. So pullups would have to be resistors (or very complex to do level shifting and inversion) This leaves RC timeconstants all over the place. Also the voltage swings would have to be greater than semiconductor technology because of poorer intrinsic conductivity. As a result, attempts at dense, fast, logic would be tied to a very unfavourable speed/power tradeoff.
It wasn't that long ago that computers used NMOS chips which work exactly as you describe.
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Old 24th Nov 2020, 9:59 pm   #67
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Default Re: Would we have got to the moon with no semiconductors?

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I was groping for an example of development potential largely unforeseen, and LED technology seems like a good case.
OLED is a much more primitive and advanced (at the same time) technology, though. It would have existed (as a development of EL technology) regardless of LED technology existing.
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Old 24th Nov 2020, 10:07 pm   #68
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Default Re: Would we have got to the moon with no semiconductors?

Don't forget magnetic amplifiers and saturable cores
All capable of amplification and switching I believe these were used in early missiles
Following with great interest
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Old 25th Nov 2020, 2:12 am   #69
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Default Re: Would we have got to the moon with no semiconductors?

I seem to remember reading, at some point in the distant past, that fluidic logic was the future.
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Old 25th Nov 2020, 6:06 am   #70
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Default Re: Would we have got to the moon with no semiconductors?

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Originally Posted by Maarten View Post
It wasn't that long ago that computers used NMOS chips which work exactly as you describe.
That's what i was thinking of. An Apollo computer could have been done.. was done in a slow, single-ended logic, and could have been done using valves, but there isn't the prospect of reaching the speeds and densities we now have. The logic in this computer I'm typing on is about 3 orders of magnitude faster than period NMOS, and the density increase is even more amazing.

Doing it with electrons in vacuum rather than electrons in crystalline solids has a number of differences. The voltage drop across switches will have to be a lot larger. Creating focused electron beams that don't stray into neighbouring elements is going to set a larger physical size. So there are going to be unavoidable ratios of parameters which will set limits on speed, density and overheating.

Of course, there could be some new discovery or invention which circumvents these limitations, but maybe it would be sufficiently different to known thermionic techniques that such a name would no longer fit anyway. It's something unexpected even now.

It's an interesting discussion. I wonder more about guided light, erbium doped light guides with gain and distributed optical pumping to power it all.

We seem to be getting towards limitations of our current style of doing things, but that impression has been floating around for decades. We've had all sorts of things which looked futuristic.... Magnetic bubbles, wafer scale integration, 'transputer' style architecture. 3-D construction. All sorts of things and some of them aren't actually as dead as is often thought.

The future has unpredictable elements and even outright surprises in store for us.

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Old 25th Nov 2020, 8:16 am   #71
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Default Re: Would we have got to the moon with no semiconductors?

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Originally Posted by rambo1152 View Post
I seem to remember reading, at some point in the distant past, that fluidic logic was the future.
I have a copy of a book titled "Fluid Logic in simple terms" by Michael J. Moylan published by the Machinery Publishing Co. Ltd. in 1968 (mine is the 1971 2nd edition).

It even shows how to make a bistable device using something call "wall attachment" and shows a picture of a commercial device made by Corning

"All the wall attacment devices so far shown can operate at pressures between about 1 and 20 psi, but the nominal working pressure is around 2 to 3 psi. The signal pressure varies with the supply but is generally between 5 and 15% of supply pressure. Switching speeds can be as fast as 1,000/sec"!

Although being a purely mechanical device its probably OT for this forum.......

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Old 25th Nov 2020, 9:30 am   #72
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Default Re: Would we have got to the moon with no semiconductors?

Quote:
Originally Posted by Maarten View Post
Quote:
Originally Posted by Radio Wrangler View Post
As said earlier up the thread (MM) there is no 'PNP' valve, maybe P channel would be a better way of phrasing it. So pullups would have to be resistors (or very complex to do level shifting and inversion) This leaves RC timeconstants all over the place. Also the voltage swings would have to be greater than semiconductor technology because of poorer intrinsic conductivity. As a result, attempts at dense, fast, logic would be tied to a very unfavourable speed/power tradeoff.
It wasn't that long ago that computers used NMOS chips which work exactly as you describe.
But as a result, there were power consumption and switching speed penalties that were only overcome, with dramatic effect when CMOS VLSI devices became practical.

John
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Old 25th Nov 2020, 10:02 am   #73
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Default Re: Would we have got to the moon with no semiconductors?

Quote:
Originally Posted by Electronpusher0 View Post
Quote:
Originally Posted by rambo1152 View Post
I seem to remember reading, at some point in the distant past, that fluidic logic was the future.
I have a copy of a book titled "Fluid Logic in simple terms" by Michael J. Moylan published by the Machinery Publishing Co. Ltd. in 1968 (mine is the 1971 2nd edition).

It even shows how to make a bistable device using something call "wall attachment" and shows a picture of a commercial device made by Corning

"All the wall attacment devices so far shown can operate at pressures between about 1 and 20 psi, but the nominal working pressure is around 2 to 3 psi. The signal pressure varies with the supply but is generally between 5 and 15% of supply pressure. Switching speeds can be as fast as 1,000/sec"!

Although being a purely mechanical device its probably OT for this forum.......

Peter
Back in 1968 as part of my job I was working on automated systems for chemical analysis. We had an STC components catalogue which had fluidlogic modules available. We decided a solid state electronic system was more practical though.
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Old 25th Nov 2020, 10:05 am   #74
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Default Re: Would we have got to the moon with no semiconductors?

Extra weight into orbit?? There you all go again....

We think of valves as big and clunky things because what you have been (OK, still are) looking at was old technology. Domestic equipment was having to make do on 1930's technology because the state-of-art stuff went to the military in WW2, and there was a bit of a slow-down after the war because no-one had any money.

If there were no semiconductors on the horizon, the military would have been (in fact were) driving forwards. There was already kit using tiny little valves so that very poratble gear could have complex circuits. The next wave was coming, but it never made it beyond niche uses because of the change to semiconductors.

A classic "bad press" for valves was the time taken to warm up. That was nothing to do with valve heaters of course! It was the deliberate slow-start of large series heater chain TVs and then a second wait for the EHT heatup. In WW2 there were transceivers that turned the transmit filaments on when you pressed the PTT - the delay was only about a second.

On size, take an early almost-computer like Colossus. It actually isn't that big, but it was made from 30's valves mounted in GPO racks because it was all they had spare. Move forwards two generations and I am sure it would go in a small suitcase. So what would it be like in another two generations of development?

One of the great misconceptions about early computers was how "big" they were. I worked on these systems and what surprised me was why they were big. It wasn't because there was a lot of circuitry. The rows of cabinets were not so full, and a lot of it was pumps, power converters, disc and tape drives units and cabling. The actual "computer" in the sense of processor and memory was really quite small. The mini revolution was not so much about shrinking the components as realizing that if you did away with the peripherals and rack-mounting and connectors - the result was a single board!
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Old 25th Nov 2020, 12:59 pm   #75
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Default Re: Would we have got to the moon with no semiconductors?

Perhaps with progress in digital computers, the capabilities of analogue computers tend to be forgotten.

This link is mostly in German but includes some English, maths, circuits and photographs of Helmut Hoelzer’s Fully Electronic Analog Computer:
https://www.cdvandt.org/Hoelzer%20V4.pdf

Synopsis:
‘A fully electronic general-purpose analog computer was designed by Helmut Hoelzer, a German electrical engineer and remote-controlled guidance specialist. He and an assistant built the device in 1941 in Peenemunde, Germany, where they were working as part of Werner von Braun’s long-range rocket development team. The computer was based on an electronic integrator and differentiator conceived by Hoelzer in 1935 and first applied to the guidance system of the A-4 rocket (Goebbels, the Nazi propaganda minister dubbed, V 2, AOB). This computer is significant in the history not only of analog computation but also of the formulation of simulation techniques. It contributed to a system for rocket development that resulted in vehicles capable of reaching the moon.’
David
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Old 25th Nov 2020, 1:01 pm   #76
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Default Re: Would we have got to the moon with no semiconductors?

Quote:
Originally Posted by GMB View Post
Extra weight into orbit?? There you all go again....

We think of valves as big and clunky things because what you have been (OK, still are) looking at was old technology. Domestic equipment was having to make do on 1930's technology because the state-of-art stuff went to the military in WW2, and there was a bit of a slow-down after the war because no-one had any money.

If there were no semiconductors on the horizon, the military would have been (in fact were) driving forwards. There was already kit using tiny little valves so that very poratble gear could have complex circuits. The next wave was coming, but it never made it beyond niche uses because of the change to semiconductors.

A classic "bad press" for valves was the time taken to warm up. That was nothing to do with valve heaters of course! It was the deliberate slow-start of large series heater chain TVs and then a second wait for the EHT heatup. In WW2 there were transceivers that turned the transmit filaments on when you pressed the PTT - the delay was only about a second.

On size, take an early almost-computer like Colossus. It actually isn't that big, but it was made from 30's valves mounted in GPO racks because it was all they had spare. Move forwards two generations and I am sure it would go in a small suitcase. So what would it be like in another two generations of development?

One of the great misconceptions about early computers was how "big" they were. I worked on these systems and what surprised me was why they were big. It wasn't because there was a lot of circuitry. The rows of cabinets were not so full, and a lot of it was pumps, power converters, disc and tape drives units and cabling. The actual "computer" in the sense of processor and memory was really quite small. The mini revolution was not so much about shrinking the components as realizing that if you did away with the peripherals and rack-mounting and connectors - the result was a single board!
At work in the early 1970's I was involved with a process control computer for an antibiotic fermentation plant ( big scale stuff!! ). The computer was made by Elliott Process Automation. Input was from teleprinter and reel to reel punched tape. Discreet transistors on edge connecters. The whole system was in an air conditioned room about 10 ft wide by 25 ft long. Processor cabinets about the size of three chest freezers.
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Old 25th Nov 2020, 2:29 pm   #77
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Default Re: Would we have got to the moon with no semiconductors?

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Originally Posted by Neutrino View Post
Perhaps with progress in digital computers, the capabilities of analogue computers tend to be forgotten.

David
Robert Heinlein in his very early sci-fi, pre computing, novels used to talk about cutting a 3D cam to act as a program to control the functions of the spaceship.
Would act as a sort of ROM.

Peter
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Old 25th Nov 2020, 2:49 pm   #78
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Default Re: Would we have got to the moon with no semiconductors?

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Originally Posted by Neutrino View Post
Robert Heinlein in his very early sci-fi, pre computing, novels used to talk about cutting a 3D cam to act as a program to control the functions of the spaceship. Would act as a sort of ROM.
I'm sure I read somewhere that the bomb-aiming computer on early bombers was a 3D cam based system, a sort-of physical analogue computing machine. Can anyone confirm this ?

The excellent .pdf posted earlier, although mostly in German, has at the very end a diagram and English description of how the V2 guidance system worked, all analogue valves !.


Cheers,

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Old 25th Nov 2020, 3:48 pm   #79
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Default Re: Would we have got to the moon with no semiconductors?

There was a proposal about 30 years ago to make tiny triodes actually by etching a silicon substrate but they didn't use any semiconductor properties AFAIK. The reason eas to make radiation-hard devices.

The cathode was a sharp tip using field emission rather than thermionic emission. The final device would be smaller than the mean free path of an electron in air at atmospheric pressure meaning it didn't have to go in an evacuated envelope even on earth.

I have no idea if anything came of this, but if the transistor hadn't been invented then it's possible integrated circuits woul use such devices.
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Old 25th Nov 2020, 3:50 pm   #80
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Default Re: Would we have got to the moon with no semiconductors?

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The computer was made by Elliott Process Automation. Input was from teleprinter and reel to reel punched tape. Discreet transistors on edge connecters. The whole system was in an air conditioned room about 10 ft wide by 25 ft long. Processor cabinets about the size of three chest freezers.
What model was it. Not an 803 or 503 by any chance?

I learned to grapple with mainframes on those. But I was recently surprised to learn that I had also encountered the same machine in a tiny box on a Nimrod aircraft! There was a military version of the same great big computer that fitted in a small box, dedicated to processing radar. Again showing that the reason for the big machines in many caninets was maintainance convenience and ease of replacing modules. If you really wanted small and light - you could have it!
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