The IBM 2540 is a punched-card computer

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manufactured by

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for use of

System/360 The IBM System/360 (S/360) is a family of mainframe computer systems announced by IBM on April 7, 1964, and delivered between 1965 and 1978. System/360 was the first family of computers designed to cover both commercial and scientific applicati ...

and later computer systems. The 2540 was designed by IBM's Data Processing Division in

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, and was introduced in 1965. The 2540 can read punched-cards at 1000 cards per minute (CPM) and punch at 300 CPM. The 2540 is based on the design of the older, slightly slower,

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Description

The 2540 attaches to a System/360 multiplexer or selector channel through an IBM 2821 Control Unit. A standard 2540 processes standard IBM 80 column

punched card A punched card (also punch card or punched-card) is a stiff paper-based medium used to store digital information via the presence or absence of holes in predefined positions. Developed over the 18th to 20th centuries, punched cards were widel ...

s. The card reader (2540R) and card punch (2540P) devices are separately addressable and function independently. The 2540 normally reads and punches

EBCDIC Extended Binary Coded Decimal Interchange Code (EBCDIC; ) is an eight- bit character encoding used mainly on IBM mainframe and IBM midrange computer operating systems. It descended from the code used with punched cards and the corresponding si ...

data, called data-mode 1.

Card reader

On the right side of the device is the reader, consisting of an input hopper holding approximately 3100 cards, and three output stackers (right to left – R1, R2, and RP3) each holding approximately 1350 cards. Cards can be directed to an output stacker under program control.

Card punch

On the left side of the device is the punch, with an input hopper holding about 1350 cards, and three output stackers (left to right – P1, P2, and RP3) each holding 1350 cards. The center stacker (RP3) is shared between the reader and the punch, but is not intended to be used by both at the same time. Cards can be directed to an output stacker under program control. The card is read after punching to ensure that the data was punched correctly.

Special features

* Column binary – this feature, data-mode 2, allows all possible combinations of holes to be read or punched in a column. * Punch-feed-read – this feature allows input cards to be read by the punch unit and data simultaneously punched into the same card. This feature was not normally supported by

spooling In computing, spooling is a specialized form of multi-programming for the purpose of copying data between different devices. In contemporary systems, it is usually used for mediating between a computer application and a slow peripheral, such a ...

software. * 51-column Interchangeable Read Feed – this feature allows the 2540 to read 51-column "stub" cards in addition to standard 80-column cards. Operator setup was required to change card size, so the two sizes could not be intermixed. Installation of this feature reduced the capacities of stackers R1 and R2 to around 800 cards, and reduced read speed to 800 CPM.

Successors

With the introduction of

System/370 The IBM System/370 (S/370) is a range of IBM mainframe computers announced as the successors to the IBM System/360, System/360 family on June 30, 1970. The series mostly maintains backward compatibility with the S/360, allowing an easy migrati ...

IBM announced the improved 3525 card punch and the 3505 card reader in 1971.

References

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External links

IBM Systems Reference Library: IBM 2540 Component Description and Operating Procedures (A21-9033-1)
2540 IBM System/360 mainframe line Card reader (punched cards)