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Why did programmers ever write their programs on punch cards? Didn't computer screens and keyboards already exist by the time programmers used them?

[W]hy did programmers ever write their programs on punch cards? Didn't computer screens and keyboards already exist by the time programmers used them?

[W]hy did programmers ever write their programs on punch cards? Didn't computer screens and keyboards already exist by the time programmers used them?

Why did programmers ever write their programs on punch cards? Didn't computer screens and keyboards already exist by the time programmers used them?

We use whatever i/o mechanism our computers have. In the 1960's, paper tape was common. In the 1970's (when I started programming), paper tape was being replaced by punched cards.

Yes, there were machines with teletypes, and also astonishing things called VDU's. But they were not in the mainstream yet. Both of these technologies were more commonly used by the (mainframe) computer operators; rarely for us.

We would send our coding sheets off to the data center, where operators would punch them in (at blinding speeds), and then pass the cards to the verify operator. She (90% of data center staff were women; only their managers were male) would type your code again, with the punch machine set to verify mode. The machine would ding if what she was typing was different to what was on the card already. By doing it twice, they achieved speed and accuracy.

When you got your cards back, the first thing you would do was draw a diagonal line across the top of the entire deck. Woe betide if you dropped your cards before doing that! With line drawn you had a fighting chance of getting your cards back in order after dropping them.

With experience you would learn the Hollerith code for each character, and could punch as fast as using a keyboard.

If no-one senior was watching when you made an error, you could fill the wrong hole with a "chad" that had been punched out of the card, rubbing it with your thumbnail so that it's edges meshed with the rest of the card. Such patches often came loose during the read process, but they often worked at least once. If the chad came out during the read process it would cause a "crash", and the following card(s) would be crushed and crumpled beyond recognition. The card reader would be jolted out of alignment, requiring a Computer Engineer to come and fix it.

In summary, we use what tools we have available. The newest technology is always the most expensive, and it can take a while before everyone has access to it. It's also a matter of convenience and skills. I am typing this on my laptop, but when writing an email on my smartphone, I use "swype" input, where my finger makes a weird zigzag pattern over a keyboard image and the software works out what word I intend.

We use whatever i/o mechanism our computers have. In the 1960s, paper tape was common. In the 1970s (when I started programming), paper tape was being replaced by punched cards.

Yes, there were machines with teletypes, and also astonishing things called VDUs. But they were not in the mainstream yet. Both of these technologies were more commonly used by the (mainframe) computer operators; rarely for us.

We would send our coding sheets off to the data center, where operators would punch them in (at blinding speeds), and then pass the cards to the verify operator. She (90% of data center staff were women; only their managers were male) would type your code again, with the punch machine set to verify mode. The machine would ding if what she was typing was different from what was on the card already. By doing it twice, they achieved speed and accuracy.

When you got your cards back, the first thing you would do was draw a diagonal line across the top of the entire deck. Woe betides if you dropped your cards before doing that! With the line drawn you had a fighting chance of getting your cards back in order after dropping them.

With experience, you would learn the Hollerith code for each character and could punch as fast as using a keyboard.

If no one senior was watching when you made an error, you could fill the wrong hole with a "chad" that had been punched out of the card, rubbing it with your thumbnail so that its edges meshed with the rest of the card. Such patches often came loose during the read process, but they often worked at least once. If the chad came out during the read process it would cause a "crash", and the following card(s) would be crushed and crumpled beyond recognition. The card reader would be jolted out of alignment, requiring a Computer Engineer to come and fix it.

In summary, we use what tools we have available. The newest technology is always the most expensive, and it can take a while before everyone has access to it. It's also a matter of convenience and skills. I am typing this on my laptop, but when writing an email on my smartphone, I use "Swype" input, where my finger makes a weird zigzag pattern over a keyboard image and the software works out what word I intend.