Hot answers tagged

96

The basic issue that paper tape is hard to edit. In theory you can cut the existing tape and splice in a new section, but in practice there is no easy way to find the correct location except by printing the contents of the tape (at 10 characters per second) and searching by hand. People did learn to read the tape hole patterns (they were no harder to learn ...


54

R&D stuff isn't manufactured (at first). It's usually partially constructed, ripped up, and redone, multiple times, with long testing and debug cycles in between, all the while with payroll running up the tab. Tons (literally) of fried or used components and partial assemblies can go into the junk bin. The specifications then often evolve with the ...


44

It might be important to know that the 3101 was neither a genuine Intel development, nor intended as a RAM - at least not in a way we see RAM today. After all, what use could there be in 1970 for a RAM 30 times faster than average core but quite small, just a few words ... hmm ... what data store can be small but should be fast? Exactly: Registers! The 3101 ...


39

Specifically concerning EISPACK. what happened was that James Hardy "Jim" Wilkinson in the UK (whose career as an applied mathematician started with practical ballistic modelling in WWII, working with Turing and other computing pioneers, and continued for the rest of his life at the UK National Physical Laboratory, not in some academic ivory tower) ...


37

Punch cards long long long predated paper tape. But there's a practical consideration you're not thinking of. If you had ever used punch cards and paper tape, you'd know: Punch cards can be dropped, and they scatter on the floor. Then you pick them up, put them all face up (by the printing on them) in the same orientation (with the one corner that's cut ...


37

there some particular design theory or constraint that made a 32-bit word size attractive for IBM to migrate to? It all comes down to the most basic data type, addressing constrains and, less important, reuse of existing memory technology. The byte size had to be a multiple of 4, as needed to accommodate BCD numbers without wasting space. So 8 was chosen ...


29

Maybe we don't always enter things twice, but verification is still a major part of software engineering. A lot of pure data entry is still done by double keying, which is to say, the data is entered twice by two different people and the results compared to try to reduce the error rate. As for programming, if you do it properly, there are code reviews and ...


24

So what was the other $478,000 spent on? Paying people to design and build it would have been a fairly big component. People often underestimate the cost of labour, particularly if it is their own time. Also looking at the photos of it on wikipedia, there were a lot of components besides valves. There were racks and other cabinets and what looks like a ...


22

The 3101 was not a product that came out of thin air. According to Intel's own sources, Honeywell Inc. had anounced they would buy 64-bit memory chips from any vendor that could supply them (so even from a then unknown newcomer like Intel). (The fact that, eventually, Honeywell did not buy from Intel, is a different story) So, this product already had a ...


20

One of the biggest factors is that when you have a machine that requires 5,000,000 successful solder joints to function properly, you need to make sure that all of your solder joints are really really good. If 1 in 10,000 of your solder joints is subtly bad, that means that the first time you try to put everything together you will have 5000 bad solders and ...


19

Without detailed documentation on the PDP-8 design process, we cannot say for sure. I suspect that while they may have briefly considered it, it was never a serious prospect. The PDP-8 is just the PDP-5 redesigned electronically. The PDP-5 was introduced in 1963 as an even-more-reduced version of a computer compared to the PDP-1 and PDP-4. The PDP-1/4 did ...


14

This might just be stating the obvious, but Type 30 manual linked in the question describes the device as a random-position point-plotting cathode ray tube. Nowhere does the manual suggest it's a vector graphics display. It then further describes how the computer supplies the X,Y coordinates of a single point to be plotted. There is no facility to plot a ...


12

Punch cards and paper tape are suited for different tasks. Punch cards work better when the size of the data is not known in advance. How long would you manufacture the unpunched paper rolls? If the roll is too long, you are wasting paper and increasing costs. If the roll is too short, you either have to splice it together, or have the operator load more ...


12

TL;DR: Yes, But... Yes, it would have been possible, but what would have been the use case? Inventions without a use case will not be picked up and thus not produced. The Details In the early 1980s, plugs with low pin density like DB-25 were common on home computers. That depends a lot on purpose. DB25 it was for high pincount, like serial or parallel ...


11

To add one more dimension to the answers already given: cards are easier to handle, whether by operators, or in a cafeteria (user self-service) system. A high-speed card reader has an input hopper and an output stacker. After reading a deck of cards, you've got a deck of cards in the stacker. The high-speed paper tape readers of my acquaintance would do ...


10

If you want to read it as octal, having the low order 3 bits grouped together is handy. Many of the early ASCII tables showed the codes in octal. HEX makes more sense once your computers begin to work on 8 bit bytes, but earlier computers had units like 36 bit words that were divisible by 3, and this led people to use octal for a few years. Punched cards ...


10

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 their way from telephone to computers. IBM might have been the first, around 1960, a bit before the /360 came which, used it a all over. *1 - In contrast, PCBs ...


10

What I'm wondering is: why punch cards instead of paper tape? Because it was already there? Early commercial computers were made to replace tabulating machines. To do so they had of course to be able to read (and write) punch cards. There was no need for paper tapes. Well, ok, paper tape was first, as the Zuse machines used them and some other experimental ...


9

There were two issues, the first being that data entry was not interactive and data was often strangely formatted to get around the constraints of the 80 column punched card so the data wasn't easy to enter. An additional problem that not all punched card machines printed on the cards as holes were punched making verification harder. So type twice to verify ...


7

An other nice thing about punch card is that you can use them, or better use a small pack of them, in another program. Some sort of copy/pasting. I remember packs of hundrands cards with colored cards slipped from time to time to physically separate subprogrames that could be reused elsewhere.


7

Here's a video about manufacturing UNIVAC 1108 (circa 1965, so a bit later but still illuminating). Notice how much is done by hand, even things like winding coils. According to the University of Minnesota the UNIVAC division employed about 10,000 people. Price list for some UNIVAC 1104 components (long page of text, search for "UNIVAC 1004 PRICE LIST&...


7

Yes. Sort of. The KDF9 had an accumulator stack (the 'nesting store' or nest) which was mostly made of fast (1µs read, 1.5µs write) core - the top 3 elements were in fast registers, with 16 words of core underneath. Arithmetic was done on the top elements of the nest, popping off operands and pushing the result in the usual manner. Though the top cells were ...


7

I'm going to say no. The PDP-8 was chiefly designed for compatibility with the PDP-5, and this machine also had no hardware stack. There is not enough room in the instruction space to add push and pop instructions either.


7

Why were these specific frequencies chosen other than needing to fit into the voice band Erm, in the end it's all about fitting in the voice band of 300..3400 Hz. For one, 1 kHz and 2 kHz are almost equally spaced within the voice band, having the maximum distance between each and its boundaries, giving optimal placement and separation. Next, 200 Hz between ...


7

The description of the Spacewar game gives some clues that the Type 30 was not able to display lines, but instead dots. Towards the end of the description, there is the listing how the spaceships were rendered, and even linear sections were given as repeated individual dots. With a true line-rendering capability, the engineers had surely used that instead of ...


6

One small reason is that you can access memory as a bit array without needing to divide (or do a modulo). Just use the bottom N bits for the byte or word or data cache line position or shift, and the rest of the bits left over as a memory address offset. Which can be done in hardware for free if needed.


6

The answer is a clear YES. What was the question again? More serious, there is no single answer. It depends on OS used Toolchain used Method used Application the data were meant for Or if there's a checking at all Already the question if something is octal or BCD or character does quite differ across applications and platforms. Then there is the factor of ...


5

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? Two will do it quite fine (*1,*2). Similar the two triodes of a 6SN7 is all what's needed - well, plus two rather equal resistors between them and another two ...


5

Worthy of mention is the rise of the microprocessor- notably the 4004 which was designed for mostly numerical operation in calculators. Whether the step to 8 bit architecture was inevitable is open to debate, but once memory ICs started being produced in 8-bit forms, it would be difficult to justify anything other than 16-bit as the next step. Looking at ...


5

A few pretty-printers were published in the 13th Pascal Newsletter in 1978. The machine-readable text of a version of the one by Hueras and Ledgard is available on the SAILDART archive. (Also on SAILDART is an unrelated formatter named PFORM, although it might be fairly specific to the weird variety of PDP-10 Pascal used at Stanford.) The source code of a ...


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