Environmental Engineering Reference
In-Depth Information
System software is usually divided into two
parts: operational software (programs directly
executed in the process of operation) and support
software (programs used during design, testing
and maintenance of operational software and
computer hardware). Examples of operational
software: input/output and communication driv-
ers; interruptions management programs; job
scheduling software; programs for the diagnosis
and management of redundancy in case of fail-
ures; library applications programs. Examples
of support software: compilers, code generators,
software offline testing, software utilities, etc.
The developed application programs were usually
integrated with operational software and hardware
directly on the operating place. Integration and
further checking (verification) took place in criti-
cal shortage of time which complicated detection
of faults that could be made during applications
software design. Defects made during software
design and not detected during verification, could
reveal themselves under specific conditions during
operation and cause failure of functions performed
by the I&C system.
Typical features of the described approach
to the design of software for I&C systems
(Figure 4): orientation at a single computer in the
system ; storage of all executable programs in the
memory of this computer; clear separation be-
tween the system and application software; design
of system and application software by different
organizations. Insufficient reliability of the first
Figure 4. Hardware and software of I&C system with centralized structure
Search WWH ::




Custom Search