Chapter Five
Information Systems Software
John
R. Taylor
C-2
1. Why do we need software to use computers?
Software
is the set of instructions that tell the computer what to do. Without a software program a computer is only
a collection of electronic hardware.
2. What are the major types of software? How can they be distinguished?
The
two major types of software are operating system software and application
software. System software tells the
different components of hardware what to do, and translates instructions
between the application software and the user.
System software programs are generalized programs that manage computer
resources. Application software programs
are designed to solve a specific problem.
3. What are the major software generations? When were they developed? Describe the
characteristics of each generation.
The
first generation of software was machine language. In the 1940's it was the only way to
communicate with computers. It was not a
very good system because writing strings of binary code was slow and laborious,
yet required highly trained specialist.
In the early 1950's the second
generation of software, assembly language was introduced. It was a big improvement because programers
could write in language-like words such as "add, sub," and
"load" then a program called an "assembler" would translate
the instruction into machine language.
Later in the 50's third generation software came along. These High-level languages used statements
were much like english, at lest relatively so.
BASIC is a high-level language.
Third generation software is still in wide use today. Forth generation software was introduced in
the late 1970's and consisted of query software, report generators, graphics
software, application generators, and other tools that greatly reduced
programing time and made it possible for non-programers to create their own
application.
4. Define an operating system. What function does it perform?
An
operating system controls the activities of the computer. It allocates and assigns system resources,
schedules the use of resources and computer jobs, and monitors computer system
activities.
5. How do a compiler, an assembler, and an
interpreter differ?
An
assembler translates assembly language into machine language. A Compiler translates an entire high-level
language program into machine language.
An interpreter translates a high-level language program into machine
code one statement at a time.