Card reader
A card reader is a device that reads punched cards and transmits their data to another device (e.g., a computer).
It either contains its own controller or is connected to an external controller, which may be a computer option, for example.
Citation from "DEC-11-HCRB-D CR11 Card Reader System Manual":
"Most available card readers operate in a characteristic manner. The reader itself consists of an input hopper for loading a number of cards, a photoelectric read station for reading data from the card, an output hopper for stacking the cards after reading, a motorized mechanism for moving the cards, and control logic for generating command and status signals.
Operation begins when the controller issues a read command. When the card reader receives this command, it picks the first card from the hopper and feeds it into the read station. As the data holes or marks pass through the read station, they are sensed by a photoelectric device. At the same time, the reader generates a series of index or clock marks. These marks are transmitted to the controller simultaneously with the data bits read from the holes in the card. Thus, the controller receives 12 bits of parallel data on the 12 data output lines of the card reader connector.
The card reader furnishes alarm signals to warn of any error condition present in the reader. It also provides signals for certain housekeeping functions such as hopper empty, stacker full, and unit busy."
