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 ...


66

The main reason punched cards aren't used any longer is density. A one-inch stack of cards is only 142 80-byte records (assuming the usual practice of encoding one byte per column). So if you need to store 50,000 records that's a stack of cards 350 inches tall (over 29 feet). And 50,000 80-byte records isn't that much, just 4 megabytes of data. If you ...


51

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 ...


44

Do the holes in Jacquard loom punched cards represent input data or program code? yes. Let me tell you a story. Somebody I used to work with many years ago was flying into the USA (or it might have been Britain from the USA) with some half inch tapes containing the source code for a Cobol program. Because he was carrying the tapes separately to his luggage,...


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 ...


36

Nice Question :)) Short answer: Density - It just takes way too much cards to store anything useful. (And no, there is no way back in the good old time of optimized data structures) When you think about it, punch cards are the safest way to backup data for long term storage. As usual that depends on your definition on 'safest way'. They are not ...


32

The symbols are as follows: (…) are used for grouping. X → Value doesn't matter I → Numeric (integer) A → Alphabetic (in this case one of N, S, E, or W) , → Used to separate each column or group definition The numbers indicate how many columns the field takes up or how many times the group is repeated. Given the desciption (1X, I2, 2X, 12 (A1, I2, 2X)) ...


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

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 ...


18

Punch cards predate computers, so yes, of course, there was. A printing tabulator like the IBM 402 or the IBM 407 should be able to do that.


17

Program code for modern CPUs, in practice, consists of opcodes which tell the CPU what operation to perform, and operands which provide data to operate on. In RISC CPUs these are necessarily both encoded into the same instruction word, while in CISC CPUs the two usually live in separate bytes, with the operands following each opcode. However there are ...


17

it says the original 8inch floppy disk from 1971 could store 80kb of data equivalent to that of 3000 punched cards Given, the text is a bit misleading, as it mixes up firsts. While it is true that the first Floppy, used in a product, in 1971, had a storage of 80 KiB (exactly 79,75), it was neither used as generic storage media not available for user storage ...


15

All code is data. But not all data is code. For example, you can take a digital photo and the numbers represent light intensity across a 2D rectangle. Nobody would dispute that this is data but not code. Code is a special kind of data which controls behaviour. ... but it's not that simple. Arguably the digital photo controls the behaviour of whatever ...


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 ...


13

Each hole in a card represents one bit: It either can be punched, or not punched. The holes in a classic card are arranged in 80 columns and 12 rows. 80 x 12 = 960, so the most amount of information that possibly could be stored on one card is 960 bits, which is equivalent to 120 bytes. In practice, most punched card applications stored one text character ...


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 ...


11

For most parts it's code. Well, code is a quite sloppy term, it covers a huge list of uses, from card scratching to encryption. So more correctly, it's a program (*1), as it defines a sequence of action to be taken by the machine - interpreted when the loom runs the cards. If at all, then thread is data. It is input from spools, processed by the loom ...


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

Your premise fails because it presumes higher density methods can't also be used. Back in the 1980s, the magazines that published code started using a barcode scheme so you could wand the program into your computer instead of keyboarding. It didn't take off, but the concept is sound. Scanning those magazine pages is trivial; Google Books has already done ...


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

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 ...


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 ...


9

I'd have added this in a comment but don't have enough rep. If you read far enough into the IBM history link given by another-dave in his answer, you'll find this quote that indicates the rectangular holes were in fact stronger: As well as handling more data, the unique rectangular hole was stronger [emphasis mine] and more compatible with the wire brushes ...


8

However, there were other possibilities, such as a later IBM format that used round holes. Not only later, but also previous IBM formats used round holes. Similar next to all other contemporary (1930s) manufacturers (Powell, CDC, Honeywell, etc). Intuitively it seems to me that round holes would be better from a mechanical stiffness viewpoint, making the ...


8

It was introduced for the same reason 2.88 MB 3.25" floppy diskettes and drives were introduced. Remember ED and how it took over from HD the way HD did from DD? No, you don't, because it never did take over, or even become popular. But they were an easily available standard (not proprietary) that continued a twenty year history of developing denser and ...


7

Many years ago I worked in a shop that had desktop apps (VB6) and mainframes. I developed an app that replaced punch cards with ASCII text. This was in the 1998-1999 timeframe. The biggest reason given was the card reader was highly mechanical and broke down several times a week. Eventually, parts were difficult (if almost impossible) to obtain. The ...


7

I think the other answers cover the topic pretty well, but allow me to ask a related question as food for thought: is the music roll of a player piano code or data? On the one hand, the piano just sits there and does nothing without the roll, suggesting that it's "code". On the other, the roll is morally equivalent to sheet music that a human musician ...


7

TL;DR; What was the DEC CR11 card reader 'compressed Hollerith code' for? It essentially allows to read arbitrary card data as distinct 8 bit values, as long they follow the 'Hollerith scheme' of decimal encoding marked up with zones. Long Read: Compressed Hollerith: 5 rows are delivered as-is, and the other 7 (rows 1 to 7) are delivered as a 3-bit ...


7

Was there any equipment which could directly print out the program or data on a stack of punchcards, without first loading the deck into a computer? No. Such a dedicated device did not exist. Neither during the time pf punch card processing (pre-electronic computer) nor and even less after electronic computers became a thing. The simple reason is that there ...


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.


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