When the system enters a wait state, IPL DOS/VS from the card reader by
causing a reader interruption. This interruption allows the system to
read the name of the supervisor from the card reader. To cause a reader
interruption, enter the CP environment by pressing the attention key
twice (or the 3270's PAl key once) to cause a CP read, and enter these commands: #cp ready OOc #cp begin
The READY cemmand causes a reader interruption; the BEGIN command
returns control to DOS/VS which reads the first spool file from the card
reader. Shortly after this card file is read, the system enters the wait
state a secend time. The user must again enter the CP environment and
enter these commands:
ready OOc begin
In response te these co •• ands, DOS/VS begins reading the IPL commands. !Qte: When initializing DOS/VS through the card reader, a user cannot
supply the responses necessary to save the war. start copy of the SVA from card input. These responses must be supplied from the console.
However, to create the SV! and SDL during IPL, place the cards to
perferm these procedures in the card reader in a separate spool file
fellewing the IPL commands. Again, the user must enter the READY OOC co •• and to cause the reader interruption to force the system to begin
reading from the card reader. DOS/VS Operation
Depending upon how DOS/VS was generated, there
operator commands and control statements that must
censole running jobs on the DOS/VS virtual machine. may be additional
be entered at the
If there is an active system recorder file, it is opened when the
first // JOB card is encountered in the input stream. Before this JCB
card is read, enter the ASSGN and SET commands that define the SYSREC device and the status of the system recorder file. Otherwise, an error
is encountered opening the SYSREC file. For example: If the system recorder file is already active on the system residence volume, enter:
assgn sysrec,X'250' (for DOS/VS Release 34 or earlier only)
set rf=yes When starting a DOS/VS virtual machine to run
process jobs from other users, a user may also
operator commands necessary to: • Allocate storage among different partitions • Start foreground partitions in operation • Initialize POWER/VS in
want
batch mode to
to enter the
These considerations are discussed later in this section under the
topic "Running Batch DOS/VS under VM/370." When alternating bet.ween CMS and DOS/VS, a user may want to keep the 1FL procedure as simple as possible. 90 IBM VM/370 Operating Systems in a Virtual Machine

STARTING A JOB STREAM
After preparing job streams and placing them in the DOS/VS card reader, the message READY FOR COMMUNICATIONS appearse Enter a null line (with the return or enter key) to cause an interruption. This interruption
causes DOS/VS to begin reading from the card reader.
If the LOG command was entered before beginning the job stream, DOS/VS cn the user's terminal all the job control statements
that are executed.
As the DOS/VS operator
8 the virtual machine user can enter control
statements directly from the terminal. For example: To execute
cataloged prcgrams or procedures, enter the ASSGN, DLBL, and EXEC statements necessary to execute the program directly from the console. WHEN A JOB IS FINISHED When the DOS/VS virtual machine running a single partition finishes
reading a spool file (which may contain one or more jobs), it posts this
attention message to indicate that the reader is empty: 1COOA ATTN. OOC If additional jcbs are in the card reader and were spooled as separate CP spool files, enter a null line to cause DOS/VS to begin reading from the card reader. If no more files are in the reader and the user
enters a null line, this message appears to indicate that operator
intervention is required: OP08A INTERV REQ SYSRDR=OOC If desired, users can put cards into the real system card reader to
direct ancther job stream to the DOS/VS virtual machine. When the DOS/VS virtual machine receives cards in its reader, it begins reading
them automatically.
If the card reader of the DOS/VS virtual machine is spooled with the
CaNT cperand, then any jobs received in the card reader while a job is
executing are read upon completion of the current job stream. If a job
stream and if the end of the spool file is reached before
another job is received, an interruption must be issued to cause the
next job to be read.
Tc terminate the DOS/VS terminal session, use the attention key (or
equivalent) to enter the CP command environment. Under CP, either enter
the LOGOFF command to log off the V8/370 system or use the IFL command to load another operating system into the virtual machine. COMMUNICATING WITH CP While operating the DOS/VS virtual machine, use CP commands to: • Ccmmunicate with the system operator or other virtual machine users • Query the status of virtual machine devices or spool files • Attach cr detach devices from the virtual machine configuation
section 3. DOS/VS in a Virtual Machine 91