Monday, 28 September 2009

I can use a model 29 card punch

I used to be able to multi-punch semi-colons using a model 29 card punch.

They could only do BCD - not EBCDIC

For those of you who have only worked on Windows or -ix systems there are other types of character representation systems than ASCII or Unicode.

IBM mainframes use(d) EBCDIC - Extended Binary Coded Decimal Interchange Code -
which is an 8 digit code, whereas BCD was only 7.

The IBM model 29 card punch had a smaller keyboard than the model 129 so if you wanted to type an EBCDIC character, such as a semi-colon then you had to multi-punch the holes into the card.

Whenever I wanted to use the card punch at college the only one available was the old style.
So I learnt to live with it.

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