101
votes
Accepted
Why were programs entered on punch cards instead of paper tapes?
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 ...
- 6,585
65
votes
Why are punch card readers no longer in use?
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 ...
- 11.3k
52
votes
Accepted
What did code on punch cards do with the other six bits per column?
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 ...
- 195k
45
votes
Do the holes in Jacquard loom punched cards represent input data or program code?
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 ...
- 10.9k
40
votes
Why were programs entered on punch cards instead of paper tapes?
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, ...
- 5,468
36
votes
Why are punch card readers no longer in use?
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 ...
- 195k
32
votes
What did code on punch cards do with the other six bits per column?
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, ...
- 2,259
32
votes
Accepted
What does this 1970s punched-card format mean?
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 ...
- 9,200
31
votes
What did code on punch cards do with the other six bits per column?
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 ...
- 5,347
26
votes
Accepted
Was any indentation-sensitive language ever used with a teletype or punch cards?
I agree to an extent that COBOL was "indentation-sensitive", but it really wasn't "indentation-sensitive" but rather "column-sensitive". The original COBOL coding format ...
- 3,254
19
votes
Was any indentation-sensitive language ever used with a teletype or punch cards?
COBOL and FORTRAN are both (or were) highly indentation-sensitive, precisely because they were created at a time when punch-cards were the most common data-entry medium. Modern editors and compilers ...
- 838
18
votes
Accepted
Was there a way to directly print out a deck of punch cards without involving a computer?
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.
- 8,892
17
votes
Do the holes in Jacquard loom punched cards represent input data or program code?
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 ...
- 16.4k
17
votes
How much data could be stored on a single punched card?
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 ...
- 195k
16
votes
How were 18-bit instructions encoded in paper tape?
The answer is invariably specific for a particular computer, and indeed may be specific depending on what is doing the reading (say, hardware bootstrap versus software loader, or what it's reading ...
- 31.3k
15
votes
Do the holes in Jacquard loom punched cards represent input data or program code?
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 ...
- 1,020
15
votes
Why were programs entered on punch cards instead of paper tapes?
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 ...
- 15.5k
15
votes
Who introduced the standard 8-bit punched tape, and when?
TL;DR:
5 hole (*1) tapes were developed as part of Murray's teletype system, the first (successful) to use typewriter keyboards as well as punch tapes. Wider (more holes) paper tapes are compatible ...
- 195k
13
votes
Were round punchcard holes mechanically stiffer?
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 ...
- 31.3k
13
votes
How much data could be stored on a single punched card?
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 ...
- 1,964
11
votes
Do the holes in Jacquard loom punched cards represent input data or program code?
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 ...
- 195k
11
votes
Accepted
Which programming systems used object files on punch cards?
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 ...
- 18.9k
11
votes
Why are punch card readers no longer in use?
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 ...
11
votes
Why were programs entered on punch cards instead of paper tapes?
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 ...
- 31.3k
11
votes
Was any indentation-sensitive language ever used with a teletype or punch cards?
Historically, was any indentation-based language ever used with pre-screen code entry technology like teletype or punch cards?
Of course, even the very first: Assembler
And it still does:
Any ...
- 195k
10
votes
Why were programs entered on punch cards instead of paper tapes?
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 ...
- 195k
10
votes
Accepted
Why ASCII paper tape has lower bit punched from the narrow side?
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 ...
- 5,093
9
votes
Accepted
Were round punchcard holes mechanically stiffer?
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 ...
- 206
8
votes
Were round punchcard holes mechanically stiffer?
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 (...
- 195k
8
votes
Why were programs entered on punch cards instead of paper tapes?
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 ...
- 181
Only top scored, non community-wiki answers of a minimum length are eligible