When the IPL procedure is complete, such messages as these appear: 01521 PAGE DATA SET EXTENT LOW HIGH
327 0 250 11 01201 IPL COMPLETE FOR DOS/VS REL xx.x ECLEVEL=nn BG 1COOA ATTN. OOC BG
As a practical matter, an installation may want to create a DOS/VS saved system at this point so that the future loading of DOS/VS would
avoid these preliminary steps. Refer to the .§I§iem for infcrmation on creating saved systems. SIGNALING DOS/VS TO READ THE JOB STREAM When DOS/VS has been loaded and the message BG indicates that it is
waiting for communication, enter a null line. This action causes DOS/VS to begin reading the next spool reader file, which is the one
that contains the job control statements, and in this example, the
assembler language source program.
If the LOG command is issued during the IPL procedure r all of the
job control statements that are read are displayed on the terminal as
they are executed. If the RDE option is in effect for DOS/VS Release 34 (or earlier),
respond to these messages before the job is executed:
1I89A IPL REASON CODE =
1I91A SUB-SYSTEM ID = When the job sent from the punch to the card reader has been read r this
message appears, followed by a time stamp: EOJ TEST1
The time stamp could look like this:
DATE 02/19/76,CLOCK 20/19/28 DURATION 00/07/48 Additional messages from the background partition can also appear, such
as:
BG 1COOA ATTN. OOC BG When punching more than one job and the spool files for rema1n1ng jobs
are still in the card reader, enter another null line to signal DOS/VS to read from the reader. Section 3. DOS/VS in a Virtual Machine 91

RELOADING CMS INTO A VIRTUAL MACHINE When a job or jobs are finished in the DOS/VS virtual may return to the CMS environment by entering CP mode
command:
ipl cms
machine, a user
and issuing this
This IPL command closes the virtual printer. sFooled to the card reader or if the printer is aessage from VM/370 appears, such as:
If the printer is
in a hold status, a PRT FILE 4786 TO BILBO COpy 01 NOHOLD --or-- PRT FILE 4786 FOR BILBO COpy 01 HOLD This Frinter file contains the SYSLST output from the job that executed
in DOS/VS. If the file is spooled to the printer, it is queued for printing on
the system Frinter. If the printer is spooled to the card reader, it is
a reader file that is available to the user in the card reader. EXAMINING DOS/VS VIRTUAL MACHINE OUTPUT To examine a jeb's output executed under the DOS/VS virtual machine, sFool the Frinter to the card reader and read the reader file onto the CMS A-disk by using the READCARD command:
readcard dostest output
This command creates a file named DOSTEST OUTPUT, which contains the sFooled Frinter output. NoW, using the CMS editor, either examine the
centents of the file or use the TYPE command to display the whole file
at the terminal. Use the EDIT command to pass control to the CMS editor:
edit dostest output
Te examine assembly er compilation output, use a LOCATE subcommand to
lecate a keyword in the listing file. For example: To locate the beginning of the diagnostic messages produced by the assembler, enter
the locate /diagnostics
If no errors are in the assembly, modify the job control statements
in the file and resubmit the job. Otherwise, correct the source
statements and then start over. Starting over means that a user must
repeat the procedure for clearing files from the card punch and card
reader, punching the IPL decks and the job stream, and reinitializing DOS/VS. 98 IBM VM/370 Systems in a Virtual Machine