72

And if you go back further, e.g. to the ENIAC, you'll see a word size of 40 bits. And if you go back even further, to mechanical calculators, you'll see word sizes determined by the number of decimal digits they can represent. And that explains the approach: Computers originally were meant to automate calculations. So you want to represent numbers. With ...


68

In the 1980's a certain bank with its headquarters in Edinburgh has a problem with (IBM) disc storage that had to be kept online for live customer account information for branch and ATM machine operation that it ran out of city buildings to put the disc drives in. Yes: Not just a building, but buildings. Luckily, just after that time radical developments ...


52

Old COBOL standards were based around 80-column punched cards, and columns beyond 71 (or 72) were reserved for line numbers. They were little used, but a numbered deck, if dropped, could be sorted by a collator. Because of this, some compilers would not parse beyond a certain column (which could be 70, 71, or 72). So, in the interests of compatibility, it ...


51

DOS/360 (As distinct from TOS/360, the tape OS) Announced at the end of 1964 per Wikipedia.


50

TL;DR; Punch card code is not binary but a collection of n out of m encodings. Long Story Yes, really a long story, so I'll only cover the main line from Hollerith to EBCDIC. There are many sidelines for special equipment, situations and as used by different manufacturers. Some covering up to 7 holes but all mostly compatible in the basic Numeric/Alpha ...


42

Word size is not really an issue in implementing C on a given architecture. There's no requirement that C types have a power-of-two size. There's only a problem if the word size is too small, but this can be simply worked around by using multiple consecutive words to represent C types like int and long. There's a long list of C compiler implementations for 8-...


31

Uppercase text only needs six bits per character. The fundamental mistake that you are making is assuming that punch codes were binary numbers. They were not. The encodings were patterns, combinations of of zero, one, two, or three holes. This is a reference card in IBM 5081 format: The row numbering was somewhat odd, for historical reasons: 12, 11, 0, 1, ...


30

But I can't seem to find any pictures of a computer filling an entire room, much less a whole multi-story building. (Image taken form Centre for Computing History) Well, for example look at this picture of a 4341 setup. This is a small entry-level mainframe of ~1980. With a believable setup for such small machine with: CPU (in the middle against the 'wall'...


30

Although you have many correct answers describing the nature of the coding used in punched cards, no one has touched on the mechanical properties of the cards. Regular users of punched cards in the past would be familiar with this issue, as getting cards through the mechanics of a fast card reader regularly and repeatedly was a major issue at the time. If a ...


27

Yes, IBM System z mainframes (and their predecessors) have been using "mainframe-on-a-chip" microprocessors for a couple decades now. In 1995 I used a IBM PS/2 with an IBM System/390 Processor Card in it running MVS. It executed System/390 instructions natively, using (I believe) one of the same microprocessors used in the System/390 mainframes of the time. ...


21

The excellent history book "AN/FSQ-7: the computer that shaped the Cold War" describes the size of a 1950's era radar monitoring air defence computer. A single installation (a single computer) was built in a specially designed four-storey "blockhouse" - 74 feet high and providing 90,000 square feet of floorspace. A separate building housed the generators ...


20

Here's a picture of the "Strela" (arrow) computer (1954) Vacuum tubes, 2000 op/sec (on 43-bit fixed point), 150kWt, 300 m³


20

Longer words mean more bits can be processed at once. An 8 bit processor can perform a 32 bit calculation, but it has to do it in 4 stages of 8 bits each. A 32 bit processor can do it in one stage. Since early computers had limited clock speeds due to slow electronics increasing the word size was one of the few options available to improve performance. In ...


19

There is some code left over in the pcc codebase showing how the GCOS compiler (for the Honeywell/GE 6000 series) worked, it used 9-bit (ASCII, most likely) characters natively, but supported 6-bit BCD characters with `STRING` syntax for encoding them in the source. The lexer support for these string tokens can be seen at old/pcc/mip/scan.c, the strtob ...


18

What is the purpose of the yellow wired panels It's the backplane, simply the wiring of the machine. on the IBM 360 Model 20? Not just there, but next to every mainframe was made that way. Depending on planned (and ordered) production run some would get printed boards, but usually all wiring was done as wire-wrap. The -20 was sold in quite high numbers ...


17

In the old days, I remember we were told to never go beyond the 70'th column in the text editor (the actual value was usually something above 70, but less than 80). [...] If it makes a difference, this was when programming COBOL. No, it doesn't, as it was more of a feature of the underlaying priciples and standards for handling punch cards. By default ...


17

The main computer hall of the company I worked for in the 1970s and 1980s was about half the size of a soccer pitch - about 200 feet by 150 feet. That contained three IBM S/370 mainframes at one end, and the rest of the room was packed full of disk drives, stacked up to 6 or 7 feet high with narrow walkways between, with the outside walls lined with tape ...


16

On the basis that a picture is worth a thousand words, I include my scan of a punched card: As amply described in the other answers, it shows how the columns are visibly marked on the card for different purposes. It makes sense when you see a card. It makes less sense when you're using a computer display or are using paper tape!


15

Here's the computer room of the Shuttle Mission Simulator (SMS), building 5 of NASA's Johnson Space Center, in the early 1980s. Most of the boxes are parts of a Sperry-Univac 1100 mainframe, but some are "intelligent controller" satellite computers, Perkin-Elmer 8/32s. There are also some Singer-Link Flight Simulation proprietary visual system cabinets and ...


14

I found the explanation in chapters 23 and 20 of Mackenzie, Charles E, Coded Character Sets, History and Development (Addison-Wesley, 1980), which was linked in a footnote to Wikipedia's ASCII article. In the early 1960s, 7-bit ASCII was being standardized as an communication format (the last I in the name comes from "interchange"), but this does not ...


13

It seems to me that a smart terminal would need a microprocessor, so I would expect them to start showing up in the early seventies, Not really, as discrete, specialized processors could do the job even before that. When did they arrive on the scene? TL;DR: Gradually between 1964 and 1971 As with every 'first' question, the answer is rather vague and ...


13

@raffzahn describes object files, which are not executable. They need to be read into the linkage editor, which produces a load module. That is what CSV (the newer name of the component that loads modules and relocates addresses) loads, and then the operating system eventually branches to the entry point (not always the first byte). What you are looking for ...


13

Yes, for the IBM 360/30 at least the 16 32-bit registers (and 4 64-bit floating-point registers) were stored in the same core memory as the main memory. The IBM 360/30 used the IBM 2030 Processing Unit as it's CPU, and the IBM 2030 Processing Unit Field Theory of Operation manual states on the page 1-4 that "The sixteen general registers and the four ...


13

A possible answer occurs to me: it might be precisely because of the slow memory. Say you want to add a pair of ten-digit decimal numbers, SUM += VAL, on a 6502. That chip has a BCD mode in which it can add two digits at a time; it has to do everything through an 8-bit accumulator. So we need a loop of five iterations, which we might unroll for speed. Each ...


13

Round holes might have been 'stiffer', but rectangular holes won on packing density. When IBM invented the 80-column card (up from the previous 40-column Hollerith card of the same size), they determined you could get more columns per card by using rectangular holes. IBM's own history describes two competing designs: the 80-column rectangular-hole card we ...


12

Such rooms were not FULL in the sense of not being able to get any more stuff in them, like a storage locker might be, because you had to be able to get to the various pieces. There was room to walk between the various items, and open panels for servicing, although sometimes not very much. But they were full in the sense that almost all available, useable ...


12

While this may cover many ways of overflow (from integer and counter all the way to record, I assume the Overflow in question is about floating point, which more precisely means over/underflow of the exponent. The exact handling varies widely between compilers and machines. Fortran 77 did not make any assumptions here (AFAIK), it at all, it was expected that ...


11

It wasn't just a Soviet thing: … This time I decided to look closely at the program deck. By now I knew just about everything there was to know about the source deck. The program deck was quite different from the source deck. To start with, it was a much smaller stack of cards. There were no letters typed on the top of the cards, and ...


11

The notation 3.2n looks to me like it means 3 x 2n rather than (3 point 2)n. So the question is whether data lengths should be based on a 6-bit unit or some 'binary' size, in practice 8 bits. The dominant character size at the time was 6 bits (with 7-bit ASCII just emerging). A 36-bit word length was also common, and was in fact the word size for the ...


10

One of the largest computers ever built was the SAGE system, built to gather information about surprise attack on the US. It filled a building. One might argue that SAGE was more than just one computer. But if you accept it as just one computer, it meets your criterion. Wikipedia Article Edit: A closer look at the Wikipedia Article shows that SAGE was ...


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