61 votes

Why were relays prevalent in early 1940s computers when vacuum tubes were also available?

Using relays to implement logic functions was already quite well understood at that time, and in fact the Post Office type relays were designed to do just that as part of the telephone system. The ...
Chromatix's user avatar
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20 votes

What would you call the occupation of a person who changes vacuum tubes?

What would you call the occupation of a person who changes vacuum tubes? Nothing specific, as it's not a job in itself, but the part of the tasks a Customer Engineer Maintenance Engineer, Field ...
Raffzahn's user avatar
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18 votes

Why were relays prevalent in early 1940s computers when vacuum tubes were also available?

Why were early 1940s computers predominantly made from relays? It was the technology proven to work reliably in large scale. A computer is large scale application, something a radio isn't. Building a ...
Raffzahn's user avatar
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13 votes
Accepted

Can I build a working(ish) vacuum tube byte?

Switching Tech Tubes I do not recommend to use them because you would need to deal with high voltage and heat dissipation which can be potentially dangerous especially in class (pupils do not act ...
Spektre's user avatar
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11 votes
Accepted

Were any vacuum tube computers built with wire wrap?

Wire Wrap as used in computers is simply a later development then the ENIAC or vacuum tubes in general (*1). The Keller tools were first marketed in 1953 and it took a few more years until they made ...
Raffzahn's user avatar
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10 votes

Can I build a working(ish) vacuum tube byte?

Nice idea. I like it. Tubes et all. My general understanding is that in early computing, pre-solid state technology, a bit would represented by a single vacuum tube. That would be a missconception ...
Raffzahn's user avatar
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10 votes

Have there been any studies comparing the reliability of relay versus vacuum tube computers?

I'm going to suggest that this is very much asking to compare "apples to oranges". Vacuum tubes have MTBF values based on their design and operating conditions but they don't experience any ...
jwh20's user avatar
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9 votes

Why were relays prevalent in early 1940s computers when vacuum tubes were also available?

An couple of under-appreciated advantages of relays over tubes is that a single relay coil could operate multiple sets of contacts, and relay contacts could easily be wired into a variety of series ...
supercat's user avatar
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9 votes

Can I build a working(ish) vacuum tube byte?

My suggestion would be to use relays. Still readily available, and while you wouldn't be using vintage parts, there were definitely some computers built with relays. Can't handle as high speed as well ...
manassehkatz-Moving 2 Codidact's user avatar
9 votes
Accepted

How many 6SN7 tubes did it take to store a bit?

But I'm used to a flip-flop being made of six transistors, which suggests it would need six triodes, Not really, a basic flip flop does not need 6 transistors. maybe there's a mix up with RAM cells? ...
Raffzahn's user avatar
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8 votes
Accepted

What's the minimum number of tubes per bit required to store a register?

The Manchester Small-Scale Experimental Machine used two Williams–Kilburn tubes to hold its registers: one stored a 32-bit accumulator, while another stored the current 32-bit instruction and the ...
scruss's user avatar
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7 votes

Did vacuum-tube computers ever reach a physical limit to their speed?

I think that vacuum-tube-based computers were limited, besides storage speed etc., by the tubes' technology itself. There do exist hundreds-MHz tubes and even GHz range ones, but they are either have ...
lvd's user avatar
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6 votes

Did vacuum-tube computers ever reach a physical limit to their speed?

Before caching, pipelining, and parallel processing (etc.) became commonly used to increase the performance of computer implementations, memory access speed was a bottleneck. Therefore, there was no ...
hotpaw2's user avatar
  • 8,183
5 votes
Accepted

IBM 650 - how many logic gates?

How many logic gates did the IBM 650 have? It's a rather useless question. When is a gate a gate? Is a wired-OR a gate? Does a 38-input-OR, used to create a zero condition count as much as a two-...
Raffzahn's user avatar
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5 votes
Accepted

Have there been any studies comparing the reliability of relay versus vacuum tube computers?

There is a case study in the form of the Harwell WITCH, which is a hybrid valve-relay based computer from roughly 1950. One of the design goals was explicitly to minimise the number of "hot ...
Chromatix's user avatar
  • 16.8k
4 votes

Have there been any studies comparing the reliability of relay versus vacuum tube computers?

This is a very interesting question. Apparently, at the time relays and tubes were used in computational equipment, there were no studies specifically regarding the lifetime of these components in ...
Thomas Perry's user avatar
4 votes

Can I build a working(ish) vacuum tube byte?

I'm personally intrigued by the use of neon lamps for storage, and although neon logic wasn't employed for anything particularly complicated back in the day, this could be a good application for it. ...
supercat's user avatar
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4 votes

Where are the Colossus schematics?

I have found a high-level diagram of the structure of Colossus I. This cites an entry in the National Archives which has not yet been digitised but looks promising.
wizzwizz4's user avatar
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3 votes

How many 6SN7 tubes did it take to store a bit?

A conventional flip flop requires the following: Two inverting switching elements that will strongly pull their output in the direction opposite what's required to turn them on. Two elements that ...
supercat's user avatar
  • 36.3k
3 votes

Were any vacuum tube computers built with wire wrap?

Not sure I would trust 30 gauge wire wrap wire insulation with vacuum tube plate voltage. The cross-talk at the higher voltages plus digital edge speeds would also be far worse.
hotpaw2's user avatar
  • 8,183
3 votes

Did vacuum-tube computers ever reach a physical limit to their speed?

In 1963 or 1964 I saw a copy of the General Radio Experimenter magazine with an article discussing whether a 1 GHz computer was possible. It wasn't optimistic. It was pre-integrated circuits, so Grace ...
stretch's user avatar
  • 131
3 votes

Why were relays prevalent in early 1940s computers when vacuum tubes were also available?

A large number of engineers had been building telephone switching networks for half a century, and phone company suppliers thus had lots of experience manufacturing good (telco quality) relays in vast ...
hotpaw2's user avatar
  • 8,183
2 votes

Why were relays prevalent in early 1940s computers when vacuum tubes were also available?

The question asked why early 1940s computers were predominantly made from relays. The answer to this question might be simplified if limited to discussion of factual commercial and military activities ...
Thomas Perry's user avatar
2 votes

Why were relays prevalent in early 1940s computers when vacuum tubes were also available?

Here is a relay computer that was built in Japan in 1958 and is still going... https://www.youtube.com/watch?v=_j544ELauus I have wound relays. It is not hard. I have never made a valve. Early ...
Richard Kirk's user avatar
2 votes

Why were relays prevalent in early 1940s computers when vacuum tubes were also available?

Relays had been around for a century. They are electrically controlled switches, naturally adapted to logical operations. There was a rich culture of using them as logical elements in telegraph, ...
John Doty's user avatar
  • 2,624
2 votes

Can I build a working(ish) vacuum tube byte?

You may be interested in this video about the restoration of a module with 8 vacuum tubes that looks very similar to the one in your video, but is a key debouncer. Details here and here. It's pretty ...
dirkt's user avatar
  • 27.4k
1 vote

Can I build a working(ish) vacuum tube byte?

Have done so long ago (RS F/F for a demonstration), without introducing brutal voltages, have lost the schematics :( What I remember is that I used an E88CC (6DJ8), with either 12V or 24V as an ...
rackandboneman's user avatar

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