conflicting characters are always interpreted as ASCII control
characters. In the secondlIode, which may be called machine-only, only
.achine control characters are recognized, and the two conflicting
characters are treated as machine.
TheDMSPIO function uses a bit in the plist to indicate which of the
two modes is in effect for printing.
ThePRINTL macro always uses ASA control character or machine control
character mode.
ThePRINT command with the CC option always runs in ASCII control
character or machine control character mode.
os simulation output, which is used, for example, by the"OVEFILE command, uses the RECFM field in the DCB or in the FILEDEF command to
determine which mode is to be used. If FA,VA, or UA is specified, then ASCII control character or machine control character mode is used. If FM, VM, or UM is specified, then machine-only mode is used. If no
control character specification is included with theRECFM, then it is
assumedthat thp linp bpgins with a valid data character, rather than with a control character, and single spacing is always usefi. Handling Interruptions
Figure 9 lists the modules that process interruptions for CMS. CMS modules are described briefly in Module Description." SVC 9
interruption processing is described in "Maintaining an InteractiveConsole Environment."
DiskI/O in eMS Files residing on disk are read and written using DMSDIO. DMSDIO has
two entry points:DMSDIOR, which is entered for a read I/O operation,
andDMSDIOW, which is entered for a write operation.
The actual diskI/O operation is performed using the DIAGNOSE code 18
instruction. Areturn code of 0 from CP indicates a successful
completion of theI/O operation. If the I/O is not successful, CP performs error recording, retry, recovery, or AEEND procedures for the
virtual machine.READ OR WRITE DISK I/O Initializes the ccw to perform read operations. Obtains the address of the disk from which to read or write. Determines the size of the record to be read or written. Gets enough storage to contain the record if the request is for
a record longer than800 bytes. DMSDIO: Reads records continually until all records for the file have been-read. 2-98 IBM VM/370 System Logic and Program Determination--Volume 2
characters. In the second
.achine control characters are recognized, and the two conflicting
characters are treated as machine.
The
two modes is in effect for printing.
The
character mode.
The
character or machine control character mode.
os simulation output, which is used, for example, by the
determine which mode is to be used. If FA,
control character specification is included with the
assumed
Figure 9 lists the
interruption processing is described in "Maintaining an Interactive
Disk
two entry points:
and
The actual disk
instruction. A
completion of the
virtual machine.
a record longer than