When using a 2741 terminal and its attention key mainly to signal CP interruptions, enter the command: tcp terminal mode cp
The first time the attention key is pressed, VM/370 posts a CP interruption. The next pressing of the attention key signals an interruption to DOS/VS. When a user is in the CP environment and wants
to signal an interruption to DOS/VS, enter either the ATTN or REQUEST commands.
Running Batch DOS/VS Under VM/370 When using DOS/VS in a virtual
likely that the virtual machine
continuously. This machine may
jobs, or it may be used only by running the production jobs. machine as a production tool, it is
running DOS/VS is going to be logged on
be available for many users to submit
installation personnel responsible for
In either event, it is likely
sFecifically for use under VM/370. whether:
that DOS/VS has been generated
In this case, a user should know • It is necessary to start more than one partition. If it is,
determine how much virtual storage to allocate to each partition.
These considerations are much the same as they would be for a native DOS/VS user, who must decide how much work is going to be done and
what is the most efficient way to do it. • To generate the POWER program (POWER/iS for DOS/iS or VSE/PCWER for DOS/VSE). This program can provide many functions that are not
available when relying solely on CP spooling, such as spooling jobs
via class and purging ,selected jobs in a job stream. When the POWER program is active in the 'DOS/VS virtual machine, it
controls which jobs are to be processed in the various partitions,
and it reads jobs from the card reader. Because the program is
constantly working, no need exists for an attention interruption
when a new job is placed in a card reader. To start the POWER program in a virtual machine, use the AUTOSTABT procedure. Enter the card deck for the automatic start either using
cards in the reader or through the virtual card reader. • Virtual devices are dedicated for use by the DOS/VS virtual machine
or devices must be shared among other virtual machines.
For example: If a card reader has been dedicated to a DOS/VS virtual
machine, then users may submit jobs through that card reader. They
de not have to place a CP ID card at the beginning of the deck to
direct it to the appropriate virtual machine. If the DOS/VS virtual
machine is sharing the system card reader, then any user submitting a card deck must place a CP ID card at the beginning of the deck,
sFecifying the userid of the DOS/VS virtual machine. Section 3. DOS/VS in a Virtual 93

Alternating Between eMS and DOS/VS Under VM/370 When working in a development and testing environment (rather than in a Latch envirenment) and the work is not suitable for these are seme advantages to alternating between CMS and DOS/VS: • Reduced unit record output. Under CMS, users can examine program output and compiler listings online, check the results and resubmit
the job without printing a single page on the system printer or
punching card decks. • Faster turnaround time compared with batch alone; under CftS, users
can see the results of program compilation and execution immediately,
rather than waiting for output from a batch system.
This topic outlines the technique for alternating between operating
systems. Before using this technique, users should be familiar with CMS, the conversational component of Vft/370, particularly with the ces editor and seme file system commands. CftS usage information is in For details on CftS commands and EDIT
subcommands, refer to LOADING CMS INTO A VIRTUAL MACHINE Te lead CftS into a virtual machine, use the IPL command. Usually, IFL CMS by specifying the sa ved system name CMS: ipl cms Or, load CMS by specifying the virtual address of the CftS system, which
is usually 190: ipl 190 After receiving a message like this: CMS VERSION 3.0 A user can use the interactive facilities of ces to prepare jobs for
execution in the DOS/VS virtual machine. USING THE CMS EDITOR TO PREPARE JOBS Use the EDIT command in CMS to pass control to the eMS editor for
preparing disk files of SO-character card image records. The created
files may contain DOS/VS job control statements, source files, or even IPL decks.
For example: To IPL DOS/VS using input statements from the card
reader, prepare CMS files that contain: • The DOS/VS supervisor name required for an IPt, such as the record: $$A$SUP1 94 IBM VM/370 Operating Systems in a virtual Machine