COMTRAN Reconstruction

J28-6169 · January 1962

03.02.04

PDF page 75 of 221. Download the scanned PDF

The page as scanned

The scan of PDF page 75 of J28-6169
Select the scan to open it at full size.

The text read off it

[03.02.04]

j) As a special option, an * in the UNIT2 field indicates that the secondary unit of a file is to be any unit on the same channel and of the same model type, which is available after all other assignments have been made. At load-time if units are available, but of a different model, one will be assigned; if no units are available on the channel, no secondary unit is assigned prior to execution of the job.

  1. Unit Assignment

    Units are assigned in the following order:

    1. System units
    2. Card units
    3. Units on specified channels
    4. Units on symbolic channels
    5. Units with model only specification
    6. Unit with no (blank) specification
    7. Secondary units designation with *

    It should be emphasized that relative unit specification is not the same as the physical setting of the tape unit. The use of A(3), for example, will result in the assignment of the third available unit on channel A; and not necessarily the physical unit A3. (An available unit is one presently attached to the machine, and not assigned for system use.) However, the assignment procedure is such that designation of a given relative unit on a given (physical) channel will always result in the same choice of unit, provided that the unit sequencing is not disturbed between jobs by use of the Basic Monitor $ATTACH – [$AS] control cards.

    When consistent tape assignments are required (e.g., when a file is used by two successive jobs or when a file is written and then read in the same job) the unit specifications should be identical in the FILE cards. The units should be specified as system utilities (UTk) or by means of specific channels (X) with low unit availability designations (k) in order to guarantee use of the same drives.

    Care should be taken in assigning system utility units (SYSUTk) to object program files. In particular, they should not be assigned to files which will specify in the printed file list the immediate mounting of tapes by the operator, since these tapes will still be in use after this list is printed.

D. *SPEC Card

The *SPEC card supplements the *FILE card in supplying file information. The format of the *SPEC card is: