[1] The 3505 and 3525 were developed at the IBM General Systems Division in Rochester, Minnesota in 1971.

When one stacker becomes full the reader automatically switches to the other, if available, to allow the operator to unload the cards without stopping the machine.

The "read column eliminate" option allows the reader to ignore data punched in selected columns, including data that would normally cause an error.

Cards may be selected into either stacker under program control.

A full stacker stops the punch, awaiting operator intervention.