the associated privilege classes. The primary system operator must have
class A assigned in the directory to properly initiate V8/370 operation. SYSTE8 DEFINITION If you intend to define or attach more than 64 virtual devices for a
single virtual machine, be aware that any single request for free
storage in excess of 512 doublewords (a full page) may cause the V8/370 system to issue an appropriate error message if the extra storage is not
available on a contiguous page. Therefore, two contiguous page frames of free storage must be available in order to log on to a virtual machine with more than 64 virtual devices (three contiguous page frames for a virtual machine with more than 128 virtual devices, etc,.).
Contiguous page frames of free storage are sure to be available only immediately after IPL, before other virtual machines have logged on.
Therefore, as a system operator you can inhibit the logon of many virtual machines until the virtual machine or machines with many I/O devices have accomplished logon and are operating. SYSTEM INITIALIZATION Successful V8/370 system initialization starts with the initial program
loading of the CP system residence (SYSRES) pack. Whether performing a
cold, warm, or checkpoint start, the following ccnditions must be met: • The processor, processor storage and all necessary devices (and disk volumes) for a minimum V8/370 system, system residence, paging, and
spooling requirements must be powered up and ready. • No unrecoverable catastrophic hardware errors are encountered in the
initialization and startup phase of bringing the VM/370 system online. • There must be a matching compatibility between the generated V8/370 SCP and the System/370 hardware and its attached features. Failure
of matching compatibility can result in an error message as well as VM/370 performance degradation (for example, refer to the V8/11Q and the message D8KCPI185E). System startup involves CP initialization; checkpoint functions; and
subsequent warm start, checkpoint, or cold start procedures. When you turn system power on, you may have to run a CS (control storage) patch
routine. This is a System/370 operating procedure and this book
discusses it nd further. System initialization establishes and maintains the integrity of V!/370 even as it is being started. Checkpoint operations provide
continuity for certain CP functions that are carried over from a previous V8/370 session. Checkpoint is invoked at initialization,
shutdown, and after a system dump. Warm start procedures allow the
operator to bring the V8/370 system up after a previous abnormal termination with certain controls saved from the previous system's session that will be used after the current system initialization is complete. The operator begins cold start if previously captured V8/370 session data or controls were destroyed or are invalid.
To initiate the operation of the V8/370 system, load the CP system residence volume. Section 2. Initiating V8/370 Operation 9

System initialization is simplified if:
1. All V8/310 resident volumes (specified in the SYSOWN list for
paging and spooling) are mounted and ready at IPL time. If volumes
specified in SYSOWN are not mounted when yeu IPL V8/370, they are
not available to You must mount and attach them later if you
need them by using the ATTACH command.
2. Volumes containing user minidisks (such as the eMS system residence volume) are mounted and ready at IPL time. However, volumes not required for startup can be attached to the system after the V8/370 program is up and operational. Once loaded, CP reads the volume identity labels of all available DASD devices, and calculates the real machine's storage size. If the configurat;on differs from that specified during system generation (SYSOWN volumes not mounted or storage size net equal to SYSCOR), a
message is printed at the system console and operation continues. If a
real machine has aore storage than what was specified on SYSCOR, it is
not used. For example: if a real machine's storage size is 1 megabyte and SYSCOR is set to 512K, 512K is used. If less storage is actually
available in the real machine than the specified SYSCOR value, the
lesser figure is used.
If the SYSCOR macro had specified AP=YES and the attached processor
is unavailable for startup, the system operates in uniprocessor mode rather than attached processor mode. During the system startup process, the use rid designated in D8KSYS is
automatically logged on as the primary system operator; he must have
class A command privileges. This process matches the userid supplied by the SYSOPR macro (used in system generation) with the user directory.
If there is an incompatibility between userids, then the automatic
operator logon process is aborted and system operational control is
given to the first user with privilege class A who logs onto the system. In the case of an automatic logon failure when a privilege class A user explicitly logs onto the system, where the system console is either
a 3210 or 3215 (or a 3138, 3148, or 3158 console in printer keyboard mode), the user must protect the security of his password as there are
no print-masking or print-inhibiting features on these devices.
After the operator has logged on, V8/370 prompts him for the type of
system start desired (whether this is a warm start or not).
At this point, the system is ready for normal use. The operator can
now: • Establish a message of the day to be issued to users when they log
on. • Enable communications lines to permit users to log on.
The Time-of-Day (TOD) clock provides an accurate measure of time, independent of system events or activities, and makes accurate
measurements available for programming applications. When system power
is turned off, the clock value is lost on some System/370 models. Once the time-of-day (TOD) clock has been made operational through the SET CLOCK instructions and the TOD ENABLE SET switch, it is incremented at a
constant rate. This timing operation is not affected by: 10 V8/310 Operator's Guide