The user has entered the following sequence of commands and data entry:
edit initload djcl
input II job intdsk II assgn syslcg,x'01f',c1 II date 12/31/75 II log II assgn syslst,x'OOe',ll II assgn sysopt,x'250',d4 II exec II uid iq II vtoc volldossys II end II job disrst II assgn sys005,x'250',d4 II assgn sys006,x'180',t2 II assgn syslst,x'OOe',ll II exec
(null line)
file
(Establish file identification)
(Start data entry) • I I I I Job
stream I I I I I I , (Terminates data entry) (Writes file on disk)
The job stream to initialize the disk and unload the tape is now a CMS file. It is identified by a filename of INITLOAD and a filetype of
DJCL.
Similarly, a user can create CMS files containing job streams that: • Unload the IBM-supplied system to disk without initializing the disk • Add 1/0 device specifications to the IBM-supplied supervisor • Define standard labels • Perform librarian functions • Assemble and catalog a new supervisor • Assemble and catalog additional 1/0 modules • Back up the new system on tape or disk COPYING DISTRIBUTION SYSTEM TO DISK
Assume that two job streams are available as CMS files: • INITLOAD DJCL X'180' initialize disk at X'250' and load from tape on • SKIPINIT DJCL --skip first file on tape and restore tape on X'180' to disk at x'250' When userid DOSVSYS logs onto the VM/370 system, the virtual machine
has every liD device it needs except for a magnetic tape unit. Since
this device is only required during the tape-to-disk restore operation,
it would be inefficient to tie it up for the entire terminal session.
Instead, send the VM/370 system operator a message such as:
msg cF Fls mount dos/vs distribution tape as 180 The system operator mounts the appropriate tape reel on some idle
tape drive, such as 183, and issues the command:
attach 183 to dosvsys as 180 76 IBM VM/370 Operating Systems in a Virtual Machine

The user receives an acknowledgement: TAPE 180 ATTACHED
The user is now ready to start syste& generation. If he 15 not in
the CMS envircnment, issue the command:
ipl cms Spool the punch to the user's virtual reader:
cp spool punch to *
If the disk is to be initialized, punch out the CMS file:
punch initload djcl (noheader)
The NOHEADER option eliminates the header record normally punched out
to identify a card deck.
After a PUNCH command, the user receives an acknowledgement that the
file was spooled to the reader.
If the disk had already been initialized, the user would have punched
out the file: LOADONLY DJCL
Now that the job streaa is in the user's virtual reader, perform an IPL from the tape by issuing the CP co.mand:
cp ipl 180 When the system goes into a wait state, press the PA1 key (or its
equivalent) to place the virtual machine in CP console mode. Issue the CP command READY OOC to ready the virtual reader. Then, issue the CF command BEGIN to return control to the system tape.
The virtual machine is now under the control of the utility programs
on tape. The virtual machine should reply to all queries as if on a
real machine. When the distributed DOS/VS has been restored to disk, the user
receives a RESTORE COMPLETE and an END OF JOB message; the virtual
machine is then placed in a disabled wait state, and the console is put
into CP mcde. To now perform an IPL from address 250, use the
distributed system to perform the rest of the system generation
procedures. READYING THE INTERIM SYSTEM The IBM-supplied supervisor does not contain any I/O device
specificaticns. Until generating a new supervisor with its particular I/O configuration, the user must include the appropriate ADD and ASSGN commands each time he IPLs DOS/VS. The following job stream files can be created for use in this and
other phases of system generation:
IPLADD DJCL STDLABEL DJCL DSERV DJCL
add and assign I/O devices
assign standard labels
display the directories
Section 3. DOS/VS in a Virtual Machine 77