CNTRL-Control Online Input/Output Device (BSAM and QSAM)
The CNTRL macro instruction is used to control magnetic tape drives (BSAM only) and to control online card readers, 3525 card punches (read and print features), and printers (BSAM and QSAM). The MACRF operand of the DCB macro instruction must specify a C. The CNTRL macro instruction must not be used for SYSOUT data sets that are temporarily stored on a direct-access device. For BSAM, all input and output operations must be tested for completion before the CNTRL macro instruction is issued. The control facilities available are as follows:
Card Reader: Provides stacker selection.
QSAM-The CNTRL macro instruction is issued whenever it is necessary to read a new card. For unblocked records, a CNTRL macro instruction should be issued after every input request except the last. For blocked records, a CNTRL macro instruction is issued after the last logical record on each card is retrieved, except for the last input request. The move mode of the GET macro instruction must be used, and the number of buffers (BUFNO field of the DCB) must be one.
BSAM-The CNTRL macro instruction should be issued after every input request. If, however, the device is allocated to SYSIN, the CNTRL macro instruction does not need to be issued after the request because the CLOSE macro instruction places the last card in the same stacker as the preceding card.
Printer: Provides line spacing or a skip to a specific carriage control channel. A CNTRL macro instruction cannot be used if carriage control characters are provided in the record. If the printer contains the universal character set feature, data checks should be blocked (OPTCD= U should not appear in the data control block).
Magnetic Tape: Provides method of forward spacing and backspacing (BSAM only).
If OPTCD=H is indicated in the data control block, the CNTRL macro
instruction can be used to perform record positioning on DOS tapes that contain embedded checkpoint records. Embedded checkpoint records encountered during the record positioning are bypassed and are not counted as blocks spaced over.
OPTCD=H must be specified in a job control language DD statement. The CNTRL macro instruction cannot be used to backspace DOS 7-track tapes that are written in data convert mode that contain embedded checkpoint records (BSAM). additional information about 3525 printing operations, refer to OS Data
Management Services Guide.
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The CNTRL macro instruction is written as follows:
[symbol] CNTRL dcb address, SS,
{~}
sp,U}
SK,
{:hrOU9h
12
}
BSM FSM
BSR [, number of blocks]
FSR [,number of blocks]
deb address
The deb address operand specifies the address of the data control block for the data set opened for the online device.
SS, {I}
{2}
The SS operand is coded as shown to indicate that the control function requested is stacker selection on a card reader; either 1 or 2 must be coded to indicate which stacker is to be selected.
{I}
SP, {2}
{3}
The SP operand is coded as shown to indicate that the control function requested is printer or 3525 line spacing; either 1, 2, or 3 must be coded to indicate the number of spaces for each print line.
{I}
SK, through {l2}
The SK operand is coded as shown to indicate that the control function requested is a skip operation on the printer or 3525 card punch, print feature; a number (1 through 12) must be coded to indicate the channel or print line to which the skip is to be taken.
BSM-Coded as shown
The BSM operand indicates that the control function requested is to backspace the magnetic tape past a tapemark, then forward space over the tapemark. When this operand is specified, the DCBBLKCT field in the data control block is set to zero.
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CNTRL FSM-Coded as shown
The FSM operand indicates that the control function requested is to forward space the magnetic tape over a tapemark, then backspace past the tapemark.
When this operand is specified, the DCBBLKCT field in the data control block is set to zero.
BSR-Coded as shown
The BSR operand indicates that the control function requested is to backspace the magnetic tape the number of blocks indicated in the number-oj-blocks operand.
FSR-Coded as shown
The FSR operand indicates that the control function requested is to forward space the magnetic tape the number of blocks indicated in the number-oj-blocks
operand.
number oj blocks-symbol, decimal digit, absexp, or (2-12)
The number-oj-blocks operand specifies the number of blocks to backspace (see BSR operand) or forward space (see FSR operand) the magnetic tape. The maximum value that can be specified is 32,767. If the number-oj-blocks operand is omitted, one is assumed.
If the forward space or backspace operation is not completed successfully, control is passed to the error analysis (SYNAD) routine; if no SYNAD routine is designated, the task is abnormally terminated. Register contents, when control is passed to the error analysis routine, are shown in Appendix A. If a tapemark is encountered for BSR or FSR, control is returned to the processing program, and register 15 contains a count of the uncompleted forward spaces or backspaces. If the operation is completed normally, register 15 contains the value zero.
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