As soon as computers came into existence they started breaking down; and breakdown they did. The early computers used vacuum tubes and would break down roughly every other day. The absolute majority of problems related to failed vacuum tubes although with so many mechanical parts, there were other breakdowns that would need addressing albeit comparatively much less frequently.

Punched cards also known as IBM or Hollerith cards were the medium used for input and output. Different codes would be represented by the presence and absence of holes in predefined positions. Programmers would have their program punched into a stack of cards. They would submit the program deck, followed by cards that held the data on which the program worked. The operator would load these cards into the card reader (together with other jobs). The operator would use a special language called the JCL (Job Control Language) to make the computer read the program into the computer’s memory and execute thereafter. The JCL instructions themselves would be entered on punched cards. Data used by the program would be loaded in a similar manner. Output from the program would be to paper if it needed to be human readable or to new punched cards if the output would have to be processed again. Today’s equivalent to punched cards is files stored on the hard disk.

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A punched card was a stiff piece of paper. They came in a variety of colours allowing colour coding of different sections of a deck such as JCL, programs and data.  Punched cards did not originate with the computer industry; they were first used in the 19th century for controlling textile looms and for operating fairground organs and related instruments.

The punched card cannot be thought of a backup in the modern sense of the word. Important programs and data cards could be duplicated just in case anything happened to the working set.  The punched cards would be stored offsite and being made of stiff material proved to be quite durable.

We’ve come a long way in the world of backups, the technologies may have changed but the purpose and scope have remained fixed.

Merry Christmas to one and all.

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