Assembly-language systems offer certain diagnostic and debugging assistance that is normally not available at the machine level.Ī high-level language such as FORTRAN, PASCAL, or PL/I offers most of the features of an assembly language.
Some assembly languages contain macroinstructions which are at a higher level than assembly-languages instructions. Moreover, memory locations are given symbolic names such as PAY and RATE. Each operation code is given a symbolic code such as ADD for addition and MUL for multiplication. Microcode allows for the expression of some of the more powerful machine-level instructions in terms of a set of basic machine instructions.Īssembly language is essentially a symbolic version of a machine-level language.
Also included as machine-level programs are programs written in microcode (i.e., microprograms). Finally, all diagnostics and programming aids must be supplied by the programmer. All bookkeeping aspects of the program are the sole responsibility of the machine-language programmer. Each instruction in a program is represented by a numeric code, and numerical addresses are used throughout the program to refer to memory locations in the computer’s memory. Higher-level or user-oriented languagesĪ machine-level language is the lowest form of computer language. This type of low-level language is quite different from the high-level language used to describe a problem in a given area.Ī hierarchy of programming languages based on increasing machine independence includes the following:ģ. These sequences are generally unintelligible to humans. Digital computers, on the other hand, accept and understand only their own special low-level language, consisting typically of long sequences of zeros and ones.
Such a programming language is usually high-level. That is, the language should contain constructs which reflect the terminology and elements used in describing the problem and are independent of the computer used. It must bridge the gap between the often unstructured nature of human thought and the precision required for computer execution.Ī program solution to a given problem will be easier and more natural to obtain if the programming language used is close to the problem. An effective programming language enhances both the development and the expression of computer programs. In computer programming, a programming language serves as a means of communication between the person with a problem and the computer used to help solve it. Language permits the expression of thoughts and ideas, and without it, communication as we know it would be very difficult indeed. Interactions involving humans are most effectively carried out through the medium of language.
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