addresses; and adding new application software.
Changes to memory, buffer size, and hardware
addresses require changes to the operating system. In
addition, you must follow the manufacturers
instructions. Memory and buffer size changes are done
when system performance has dropped because of
increased use or changes to peripherals. By increasing
memory and buffer sizes, the throughput time of the
system is improved and the user access time is
shortened. Hardware addresses are changed when there
is a change to hardware status, such as the addition or
loss of a piece of equipment. The addition of new
application software will cause the system to be
unavailable to users during the implementation. When
the software arrives, it will include the installation
instructions that are to be followed.
Powering Up the Computer
The CPU is normally powered up first; then one by
one, each of the I/O devices is turned on. This is done to
prevent a sudden surge of power that might overload the
circuits. With the computer system powered up, you
can then proceed to IPL the system.
Booting the System
Anytime the system loses power, is shut down, or
becomes disabled because of a system crash, it usually
needs to be rebooted or initial program loaded (IPLed).
A system crash is the result of a hardware, software, or
a malfunction in the CPU, a
programming error from which the operating system
could not recover, or an operator error caused by an
incorrect response to a message. Booting most systems
resets all status indicators and reloads the supervisor
(the executive-system program along with other
resident routines) into the CPU memory. The manner in
which the system is booted depends upon the computer
system used and the software included in its operating
system. Many of the larger mainframe computers store
their operating systems on disk, and this disk is referred
to as the SYStem RESident (SYSRES) pack. Once the
disk unit with the SYSRES pack is in a ready status, you
can then boot the system. Some systems are so simple to
boot that all you need do is depress the start (or load)
button on the CPU (or master console) and enter the date
and time on the console keyboard. Some of the more
complex systems may require you to take additional
stepsassigning various I/O devices, partitioning
(sectioning off) memory, and so on. It is because of
these differences that boot procedures are well
documented with each step explained to the point that
anyone, even someone unfamiliar with the system,
could follow the step-by-step directions.
Computer diagnostics are of two types: those that
are run when the computer is booted (called internal
diagnostics), and those that can be run from a peripheral
device (called external diagnostics).
INTERNAL DIAGNOSTICS. Internal
diagnostics are performed when the computer is booted
and are designed to test the computer hardware. They
return a pass/fail result to the operator. Some of the
internal diagnostics are designed to test all or selected
sections of the computer. An example of an internal
diagnostic test is the power on-self test (POST), that
checks the components upon power on.
EXTERNAL DIAGNOSTICS. External
diagnostics can be loaded into the computer from a
peripheral (disk or magnetic tape unit) but initiated and
controlled by the computer. These diagnostics are very
thorough and offer the option of testing all or specific
sections of a computer. They are more comprehensive
than the internal diagnostics.
RESPONDING TO MESSAGES
Unless you respond correctly to a system- or
program-generated message, CPU time can be lost, the
wrong program options can be executed, and the system
can even become disabled. As a console operator, you
are the most important part of a team effort that makes
computerized procedures successful. It is true that while
complex operating systems make it easier for you to
perform various tasks, correct responses to messages
are just as critical.
Never second-guess a response.
Always refer to the proper documentation to determine
the response needed.
Manuals provided by the
manufacturer, operators manuals, and error message
manuals should be located as near to the console as
possible for your convenience.
Basically, you will be concerned with two types of
messages: system-generated messages and program-
System messages are generated by the operating
To be more specific, it is the
executive-program (the supervisor) that is responsible
for monitoring and allocating the resources of the