r-------------------------------------------------------------------------, CMS cp close OOc cp purge OOc all
cp close OOd purge
cp spool OOd to * cont
punch jobcard jcl (noheader)
punch pliccmp jcl (noheader)
punch plimain pli (noheader)
punch asmcomp jcl (noheader)
punch asmsub assemble (noheader)
punch linkgc jcl (noheader)
punch godata dat (noheader)
punch slshstar jcl (noheader)
cp spool OOd nocont
cp close OOd cp spool OOc cont eof
cp ipl 230 N0ig: The following are issued once under OS control: IEE007A READY set date=xx.355,Q=(231)
start rdr,OOc start wtr,OOe start
Figure 3. OS Job Stream Transfer
To transfer files between systems, the user must have access to both operating systems being used. Access to both systems can be provided either in the virtual machine's VM/370 directory entry, or dynamically
before loading the new system.
Figure 4 illustrates a virtual machine configuration and the
corresponding VM/370 directory control statements. Virtual device
addresses 190 and 191 contain the CMS system and user disk area. Virtual device addresses 230 and 231 contain the OS system and user disk
area. The two systems use a common card reader, card punch, printer,
and console.
r-------------------------------------------------------------------------, USER OS2 PASSWORD ACCOUNT NUMBER BIN16 CONSOLE 01F 3215 SPOOL C 2540 READER SPOOL D 2540 PUNCH SPOOL E 1403 LINK JFK 230 230 R
LINK CMSSYS 190 190 RR MDISK 231 2314 120 82 UDISK1 WR MDISK 191 2314 101 10 DDISK1 WR RPASS WPASS Figure 4. Directory Entry for Alternating Between Operating Systems I I I I I I I I , I Section 1. General Considerations 25

Users can alternate between operating systems more simply if: • Devices used by both systems are supported at the same device
address.
--and-- • Common addresses are not used to support different devices.
If these two conditions are not met, the user must modify the virtual machine configuration before each IPL of a new system.
If the two systems require online typewriter keyboards at different
addresses, use the CP DEFINE command to change the address of the
virtual system console. For example: The as system (specified above)
requires an online typewriter keyboard at address 01F, while the ces system probably has its console at address 009. In this case, issue
this command before loading 230:
cp define 009 as 01f
Because CMS automatically communicates with any valid multiplexer
address, a user can leave the console at 01F and satisfy both systems. If the systems expect different device types at the same address, the
coamon address must be assigned to the appropriate device each time a new system is loaded. If CMS is running with a disk at address 191 and
os is generated to support a 3330 at that address, issue the following
command before loading os:
cp detach 191
An appropriate device can then be added to the virtual machine at
address 191. Add the device either before loading or in response to a mount request from the os system. For direct access storage devices, this procedure is necessary
even if both systems support the same device type at the same address.
Except for VSAM disks, the disk format used by ces is unique. It is not compatible with that of other operating systems. Files can be shared between CMS and as or DOS only through VM/370 spooling or through VSle data sets. MULTIPLE-ACCESS VIRTUAL MACHINES Multiple-access programs execute in a virtual machine and directly
centrol terminals. These terminals do not have to be supported by VH/370 as virtual operator consoles, but they may be of any type
supported by the virtual machine. These programs use lines that are
either dedicated to the virtual machine (by the directory entry) or
assigned to the virtual machine dynamically.
For example: Figure 5 shows two multiple-access systems (controlled
by virtual machines VM1 and VM2). While each system controls real 3277s
by using part of the real 3272, the real 3272 appears to both virtual machines as though they each have sole control of it. (The virtual
system consoles of VM1 and VM2 are not shown.)
26 IBM VM/370 Operating Systems in a Virtual Machine