The virtual machine console is assumed to be a 3270 display terminal. USER DOSVSYS PASSWORD 512K ACCOUNT ACCTNO BIN4 OPTION ECMODE CONSOLE 009 3210 SPOOL OOC 2540 R SPOOL OOD 2540 P SPOOL OOE 1403 LINK CMSSYS 190 190 RR MDISK 191 3330 50 5 UDISK3 MR MDISK 250 3330 0 404 DOSSYS MR Figure 15. virtual Machine for DOS/VS System Generation
In addition to the devices specified in the directory entry for user DOSVSYS, this user needs a dedicated magnetic tape unit at
address 180 on which to mount the distribution tape. the attachment of
the magnetic tape drive is discussed later in this topic. BUILDING SYSTEM GENERATION JOB STREAMS During the entire system generation process, the user supplies the
virtual machine with job streams to perform the individual steps. On a
stand-alene system, these job streams are usually kept in card form. Under VM/370, the CMS editor can be used to create CMS files containing
these job streams. Once created, use the VM/37C spooling functions to Flace these jcb streams into the virtual machine's card reader whenever
they are needed. This technique is especially helpful when the virtual
ccnsole is seme distance from the real reader.
Te generate a tape and disk configuration, unload the IBM-supplied
tase system from a distribution tape to an initialized DASD volume.
Create two small CMS files. These files contain the card reader input
data for the two utility programs that occupy the first two files on the
distribution tape. The file assumes: (1) the user logs onto VM/370 as
user DOSVSYS, and (2) the user is in the CMS environment. Section 3. DOS/VS in a Virtual Machine 75

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