UNIT-REFERENCE NUMBER ASSIGNMENT

The Basic Control System allows reference to input/output equipment through use
of unit-reference numbers. The relationship between a unit-reference number and
a particular device is established during Prepare Control System processing.

Unit-reference numbers are divided into two categories: Standard units and instal-
lation units. The Standard units have "standard" usage among user programs and
the standard software systems (Startard unit names are used to describe the oper-
ating procedures for the systems). Installation unit numbers are defined for each
configuration. An installation unit-reference number and one or more Standard
unit-reference numbers may all represent the same physical device; they are linked
through tables interfnal to BCS or defined according to parameters supplied to the
SIO Dump routine.

The table below may be used to record the assignment of input/output equipment for
a particular installation.

Unit-Reference  Standard Unit  Typical Equipment  Actual Equipment  Channel
Number          Name           Type               Type              Number

      1         Keyboard Input 2752 Teleprinter   ________________  _______

      2         Teleprinter    2752 Teleprinter   ________________  _______
                Output

      3         Program        2737A Punched      ________________  _______ 
                Library        Tape Reader t

      4         Punch Output   2753A Tape Punch   ________________  _______

      5         Input          2737A Punched      ________________  _______

      6         List Output    2752A Teleprinter  ________________  _______


                 INSTALLATION UNITS

Unit-Reference    Actual Equipment    Channel
Number            Type                Number

      7           ________________    _______

     10           ________________    _______

     11           ________________    _______

     12           ________________    _______

     13           ________________    _______

     14           ________________    _______

     15           ________________    _______

     16           ________________    _______

     17           ________________    _______

     20           ________________    _______

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t For Magnetic Tape System, the Program Library is assigned to the
  HP 2020A Magnetic Tape Unit.
G-1