As shown in Figure 1, the virtual machine operating system may be one
like VM/310 itself, or TSO, that supports a number of remote terminals.
To assign a real line as a virtual line, the terminals supported by
the virtual machine's operating system are of the same type as those supported by VM/370 as virtual system consoles. To make this assignment, define the virtual lines either in the virtual machine's VM/310 directory entry (via the SPECIAL control statement) or add them
to the logged-on virtual machine (via the CP DEFINE command). VMl VM/310 Control program of Real VM/310 Virtual 2102 r I 3212
L __ I I Real 3105 I I (In 2103 Emulation Mode) I L-_________________________I I ,.--, .--. ,.--, ,.--, I II II II I L-J L-..J L-J L-..J '---__ ----.J V Data Sets I I I Ilocal I 3210 Figure A Virtual VM/310 Multiple-Access System Figure 8 a VM/310 directory entry for a multiple-access
virtual machine to run VM/310 under rr------------------------------------------, USER VM310 PASSWORD 1M OPTION REALTIMER ECMODE CONSOLE 01F SPOOL OOC SPOOL OOD SPOOL OOE DEDICATE 190 DEDICATE 191 SPECIAL 080 SPECIAL 081 SPECIAL 082 SPECIAL 083 SPECIAL 070 3215 2540 2540 1403 SYSRES SYSWRK 2102 2102 2102 2102 3270 READER PUNCH A IBM IBM IBM IBM B
Figure 8. Directory Entry for a Multiple-Access Virtual Machine Running VM/370 under VM/310 28 IBM VM/370 operating Systems in a Virtual Machine

Page of GC20-1821-3 As Updated April 1, 1981 by TNL GN25-0840 To connect a terminal supported by both VM/370 and a multiple-access
system, use the CP DIAL command. Such terminals can be on either
non-switched or switched lines. To connect a terminal to the virtual
machine defined in Figure 8, enter this command:
dial vm370 The VM/370 system matches the terminal type to an equivalent virtual
line that is available and enabled (in this example, 070, 080, 081, 082, or 083). Once a connection is made, the virtual machine controls the
terminal to which it is logically connected (in this example, the VM/370 virtual machine). It remains connected until logoff using standard
logoff procedures or until the virtual ,machine is forcibly logged off. Once logged off, the user is then free either to log onto VM/370 or to
use the DIAL command to contact another multiple-access system.
Dial-up terminals supported by a multiple-access system may be of a
different type than those supported by VM/370 as virtual system
consoles. Such terminals must be on switched lines, and the CP DIAL
command cannot be used. Users must dial the multiple-access system's
telephone numbers directly.
As shown in Figure 9, a communications system can be tested by using
multiple virtual machines in place of multiple real machines. For
example: While there exists a single two-line 2701 on the real machine,
the virtual 2701 units could each be defined as a one-line 2701. System/370 VM1 VM2 r--------, I I I I I I , VM/370 virtual 2701 Virtual 2701 L- ____________________ I I I Real 2701 I L--, I I r------, IData I <------------------------------->IDatal I set I Communications Line I Set I , .J I , Note: This fiqure assumes that the real 2701 transmission control unit Is-equipped with the appropriate data sets and line capability.
Figure 9. A Communications Test System Section 1. General Considerations 29