|A24-3312-7_2821_Component_Descr_Nov69.pdf|| File Number 8360-03
Systems Reference Library
IBM 2821 Control Unit
This reference publication presents a description of
input/ output operations controlled through the IBM
2821 Control Unit. The IBM 2540 Card Read-Punch
and the IBM 1403 and 1404 Printers controlled by the
IDM 2821 Control Unit are briefly described.
Commands, status, and sense information pertaining
to the attached input/output units is presented. Pro-
gramming timing considerations for control unit,
card reader, card punch, and printers are also
For further information about the attached
input/output units, refer to IBM 2540 Card Read-
Punch, Form A21-9033, IBM 1403 Printer, Form
A24-3073, and IDM 1404 Printer, Form A24-1446.
For further information about input/output and .
channel operations, refer to IBM 8ystem/360
Principles of Operatio|