150 Computer Architecture and Organization
6.2 HIGH LEVEL, ASSEMBLY AND MACHINE LANGUAGE
For the usage of computers, three different types of languages are available. They are designated as high
level language, assembly language and machine language. In this section, we are brie y introduced to
all three languages.
6.2.1 High Level Language
In general, software for computers are developed using high level language, e.g., C++ or Java. These
high level languages are semantically closer to the English language. That is the reason for the popular-
ity of these languages. They are easily understandable to us. In general, any program is composed of
instructions to move data from one place to another and process the data. For the sake of example, we
present a few lines from a program written in FORTRAN, a high level language with a very less prob-
ability of being known to the reader. The program segment is presented without any comment statement
to clarify its steps.
READ (SCORE)
IF SCORE < 30 THEN GOTO 100
PRINT (“Pass”)
RETURN
100 PRINT (“fail”)
RETURN
Assuming that FORTRAN (of any version) is unknown to the reader and further assuming that
the reader has currently gone through the FORTRAN program segment listed above, see whether
the intention behind these few instructional steps might be guessed . Experience of the present author
indicates that about 95 per cent of us would correctly interpret this program without having any prior
knowledge of FORTRAN, except vaguely remembering that it is the name of some high level pro-
gramming language.
To satisfy the curiosity of the reader regarding the predictions of the actions implemented through
above programming steps, it may be clari ed here that this program reads a variable named SCORE
and if it is less than 30, it would print fail , else it would print Pass . If the reader wants to modify the
constant ‘30’ to 20 or 10, there will not be any objection from the present authors side. However, it
might be interesting to note that within the rst two paragraph of this section, the word FORTRAN may
be replaced by BASIC and the program segment need not be changed. If the reader is an expert (and
Software developed for Intel 8080 processor would work perfectly in Zilog Z80 processor.
However, this is an exceptional case. As a matter of fact, the team of designers for 8080
designed Z80 processor at a later date.
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