Before using the virtual punch to punch jobs to a virtual machine,
take the Frecaution of clearing any files or card images that may remain
iD it from Frevious jobs. The following commands ensure that the virtual Funch does Det have any other punch files in it:
spool punch nocont
close punch purge
A user should also issue these commands to purge any eXisting reader
files of the virtual machine that run DOS/VS: spool reader nocont
close reader
purge reader Of ccurse, do not purge any needed files
ottain data about existing reader files
the command:
that may be in the To
before they are purged, enter query reader all !2te: If any files are open, this command does not tell the user that
they are open.
Loading DOS/VS This topic describes one method for loading DOS/VS in a virtual machine.
It shows how to enter the commands and control statements to IPt DOS/VS and how to ready DOS/VS for input jobs. Following the description of
the method is an example of how to 1PL DOS/VS from the virtual card
reader. IPL FROM THE CONSOLE When a user is sure that he has all the virtual unit record devices he
Deeds, that the console is properly defined, and that all required DASD devices are attached, he should enter this command to make extended
centrol (EC) mode active for the virtual machine because DOS/VS needs EC mode to page:
set ecmode on
Hcwever, if this option is specified in the virtual machine's directory
entry, the user does not have to specify it. To load DOS/VS into the virtual machine, enter the 1Ft command:
ipl 250 After a few seconds, the system enters a wait state. Cn a real system
consele, the wait light goes on. On the terminal, a user may want to let
a few seconds pass to be sure that the wait state has been entered. To
verify that the system is in a wait state, enter CP mode and use the DISPLAY command to display the PSW: display psw If bit 14 is a 1, the system is in a wait state.
BEGIN command to resume program execution.
86 IBM VM/370 Operating Systems in a Virtual Machine If not, use the

After determining that the system
attention interruption by pressing the
The following message asks the user to
supervisor:
is in a wait state, cause an
attention key (or equivalent).
enter the name of the DOS/VS or03A SPECIFY SUPERVISOR NAME
Entering a null line causes DOS/VS to use the default supervisor. $$A$SUP1. Shortly after entering the supervisor name, the system enters the
wait state again. Allow a few seconds to pass to be sure that the wait
state has been reachede Then, cause another attention interruption with
the attention key.
Next, DOS/VS displays a series of messages that display the status
of the IPL procedure, followed by a prompting message: OI10A GIVE IPL CONTROL COMMANDS In response to this message, enter these commands in this order:
1. The ADD or DEL commands to optionally alter the default DOS/VS configuration, which is established at system generation.
2. The SET command (required) to initialize the date and time clock.
3. The CAT command to optionally define the VSAM master catalog.
4. The DPD command (required) to define the page data set.
After entering the DPD command, this message appears: OI201 DOS/VS IPL COMPLETE It signifies that DOSjVS is loade,l into the virtual machine.
If a warm start copy of the SVA (shared virtual area) is available.
this message also appears: 1TOOA WARM START COpy OF SVA FOUND In response, enter KEEP (or a null line) or REJ, depending upon whether this copy of the SVA is to be used.
If no warm start copy of the SVA is available and the
used, create one by using a standard procedure, depending
available in DOS/VS. When the IPL procedure is complete, this message appears:
BG 1IOOA READY FOR COMMUNICATIONS SVA must be
upon what is
It indicates that the background partition is running and is ready to
accept control commands or job control statements.
The ccmplete VM/310 lcgon and DOS/VS IPL procedure as it would appear
on a 3210 terminal is shown in Figure 16. The exclamation marks (!)
indicate pressing the attention key (or its equivalent) a Section 3. DOS/VS in a Virtual Machine 81