IBM 2501

The IBM 2501 is a punched-card reader from IBM with models for the System/360 and System/370 mainframe systems and for the IBM System/360 Model 20, the IBM 1130 and IBM System/3 minicomputers. 2501 models can read 80-column cards at either 600 or 1000 cards per minute (CPM).[1]

The 2501 is no longer sold, but is supported by software of current IBM systems.[2]

Models

The 2501 comes in four models depending of speed and attachment features. Models for mainframe use come with an integrated control unit that performs the functions of a control unit required by other devices.

Model speed (CPM) Integrated
control unit?
A1 600 no
A2 1000 no
B1 600 yes
B2 1000 yes

Usage

The 2501 uses a photoelectric sensor to read the data punched in the card. Cards are read serially (column by column) and the reader uses a simplified "straight through" card path. "Each column is read twice and the two readings are compared to check reading accuracy."[3]

In a mainframe environment the 2501 was frequently used for mainframe input in an "open shop" environment where users submitted their own jobs.[4][5]

On an 1130 system the 2501 can be used in addition to the IBM 1442 Since the 1442 has a maximum speed of 300 or 400 CPM attaching a 2501 provides a significant increase in read speed and lower CPU usage.

The System/3 normally processes 96-column punched cards, the 2501 provides alternative input for shops that require the ability to read 80-column cards.

Features

A special feature (RPQ) is available for all models to allow them to read optically-marked (OMR) cards.[6]

See also

References

  1. ↑ IBM Corporation (1967). IBM Field Engineering Theory of Operation: 2501 Card Reader Model A (PDF). Retrieved July 29, 2016.
  2. ↑ IBM Corporation. "Identifying I/O device requirements". IBM Knowledge Center. Retrieved July 29, 2016.
  3. ↑ Shubs, Howard. "Punched Card Input/Output Devices". IBM1130.net. Retrieved July 29, 2016.
  4. ↑ Da Cruz, Frank. "The IBM 2501 Card Reader". Columbia University Computing History. Columbia University. Retrieved July 29, 2016.
  5. ↑ University of Michigan (September 1980). Introduction to the Computing Center. p. 93. Retrieved July 29, 2016.
  6. ↑ IBM Corporation (November 1969). IBM 1130 Computing System, IBM[ System/360 Models 25, 30, 40, 44, 50, 65, and IBM System/360 Model 20-Special Feature Description Optical Mark Reading for IBM 2501 Card Reader and IBM 2560 Multi-Function Card Machine (PDF). Retrieved July 29, 2016.
This article is issued from Wikipedia - version of the 9/13/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.