Editing Keypunch (section)

===IBM 129 Card Data Recorder===
[[File:IBM 129 Card Data Recorder.jpg|thumb|left|An IBM 129 Card Data Recorder]]
[[File:GfhR (14).jpg|thumb|IBM 129 Combination Keyboard. Card is punched with the letters of the alphabet and the digits 1 through 0.]]
Introduced with the [[System/370]] in 1971, the IBM 129 was capable of punching, verifying, and use as an auxiliary, on line, 80 column card reader/punch for some computers. A switch on the keyboard console provided the ability to toggle between the punch and verify modes.

The transistorized IBM 129 Card Data Recorder's primary advantage over other IBM keypunches was that it featured an electronic 80-column buffer to hold the card image. When using earlier IBM<!-- have to state IBM here, as Remington Rand keypunches always worked like the 129--> keypunches, a keystroke error required the card to be ejected by pressing the Release and Register keys, the error corrected by pressing the Duplicate key until the error column was reached, typing the correct data for the rest of that card, then pressing the Release key and manually removing the bad card from the output card stacker before it was placed in the deck (this required some practice, but quickly became an automatic action that you no longer had to think about). With the 129, a keystroke error could be erased by pressing the [[Backspace]] key and re-keyed. The entire 80-column card was punched automatically, as fast as the mechanism could go, when the Release key was pressed.

[[File:IBM 129 SLT modules.jpg|thumb|SLT modules in the IBM 129]]
Logic was in [[Solid Logic Technology|SLT]] modules on a swing out, wire-wrapped backplane.

A secondary advantage of the 129 was that the speed of the keying operation was not limited by punching each column at the time of the keystroke.

The 129 could store six programs in its memory, selectable by a rotary switch. Unlike earlier keypunch machines, the program cards were read into memory via the regular card-feed path, and were not wrapped around a "program drum".

Thanks to its use of electronic memory, the 129 did not have a separate "read station" with a pin-sense unit to enable duplication of data from one card to the next. Instead, duplication was based on the stored image of the previous card. Cards could also be "read-in" through an optical read unit integrated into the punch station.