r I I I SrEP ACrION I , , , , , I I I I , I I I I I , L FUNCTION d. reconfigure the virtual
machine
e. communicating with the
virtual machine
f. handling errors
g. end session DESCRIPTION DEFINE and DETACH
commands (Figure 10) ICP, ADSTOP, ATTN,
BEGIN, EXTERNAL, IPL, REQUEST, SET commands
(Figure 10) TRACE, DISPLAY, and DUMP commands
(Figure 10) LOGOFF command
(Figure 10) Fiqure 5. Controllinq the virtual Machine During a Terminal Session (Part 2 of 2) Controlling Input and Output Functions directory entries for your virtual machine include, among
other the 1/0 configuration required to run whatever operating system you are using in that virtual machine. This usually
includes virtual console, virtual printer, a virtual card reader, a
virtual punch, and virtual disks. A typical entry would look like:
(1 ) USER VMUSER 123456 512K 2M G ACCOUNT 87321 BIN14 (2)
(3) OPTION ECMODE CONSOLE 01F 3270 (4) SPOOL OOC 2540 R
(5) SPOOL OOD 2540 P SPOOL OOE 1403 MDISK 130 2314 050 050 VDISK1 WR RWPASSWD (6) MDISK 151 3330 001 020 VDISK2 WR RWPASSWD LINK CMSS YS 440 190 RR !!!gtg: (1) The lserid of this virtual machine is and the password is
123456. The virtual machine's storage size is defined as 512K; however, this can be redefined up to 2 megabytes if, during a session, the need for additional storage arises (see the topi: on "Reconfiguring the virtual Machine"). The user privilege
class is G.
(2) generates accounting data for processor time and 1/0 device usaqe. This data is charged to a virtual machine by account number,
which in this case is 87321. BIN14 is a distribution code that is
printed or punched on spooled printer and punch output or it is spooled to a virtual reader. It usually denotes a location where
the lser can pick up spooled output of a terminal session. 14 VM/370 CP Command Peference for General Users

(3) OptiJn ECMODE allows the virtual machine to use the complete set of virtlal System/370 control reqisters and the dynamic address
translation feature of the System/370. (4) The address of the virtual machine console is 01F, and your system corresponds with the terminal as if it were a .... ,... .. I:" I"")"' ... n ..)":;I:J,..)":;IV. (5) The virtual unit record devices (reader, punch, and printert are to
be and their addresses, as far as the virtual machine is
concerned, are OOC, OOD, and OOE, respectively.
(6) In this configuration, a 50 cylinder read/write minidisk with a
virtlal address of 130 is located on cylinders 50 through 99 of a
real 2314 volume labeled VSDISK1. Similarly, a 20 cylinder read/write minidisk with a virtual address of 151 is located on
cylinders 1 through 20 of a real 3330 volume labeled VDISK2. The
last entry provides a to a sharaole eMS system volume so the
user can use such CMS functions as the CMS editor or the EXEC processor. The LINK entry makes the virtual disk at virtual
address 440 available to your virtual machine in read-only mode at virtual address 190. NQi§§: 1. The cead password entry (RR) on
with the proper password can
read-only mode.
the LINK command means that anyone
share the use of the minidisk in
2. The access mode (WR) on the LINK command means that you can write to the disk as long as no one else has a link to it; if someJne else links to it before you log on, you still have read-only access.
3. detailed information on directory "Directory Control Statements" in the entries, see the section Some ievices such as unit record devices (readers, printers, and
punches) are usually defined as being spoolei; in this way, a few real
unit record devices can support a larqe number of virtual unit record
devices. Other devices such as magnetic tapes require a one-to-one virtual to
real This means that for its period of use, the device
must be dedicated to one virtual machine. For this reason, these devices are not permanently assigned; (that is, they are not defined in
the user's VM/370 directory entry). They are temporarily attached to a
user's victual machine as needed. VIRTUAL DISKS ITnder VM/370, a single real direct access storage device (DASD) can be
manaqej as if it were made up of a number of virtual disks (minidisks). Virtual disks, to VM/370, are extents on real DASD. To the virtual
machine, they functional equivalents of real disks. They can range
from 1 cylinder to all of the cylinders available on a real volume. Virtual disks can be permanently or temporarily defined for your virtual
mach ine.
section 3. CP Command Usage 15