Accession Number:

AD0773837

Title:

On the Criteria to Be Used in Decomposing Systems into Modules

Descriptive Note:

Corporate Author:

CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF COMPUTER SCIENCE

Personal Author(s):

• Parnas, D. L.

Report Date:

1971-08-01

Pagination or Media Count:

29.0

Abstract:

The paper discusses modularization as a mechanism for improving the flexibility and comprehensibility of a system while allowing the shortening of its development time. The effectiveness of a modularization is dependent upon the criteria used in dividing the system into modules. Two system design problems are presented, and for each, both a conventional and unconventional decomposition are described. It is shown that the unconventional decompositions have distinct advantages for the goals outlined. The criteria used in arriving at the decompositions are discussed. The unconventional decomposition, if implemented with the conventional assumption that a module consists of one or more subroutines, will be less efficient in most cases. An alternative approach to implementation which does not have this effect is sketched.

Descriptors:

• *COMPUTER PROGRAMMING
• *MODULAR CONSTRUCTION
• DECISION THEORY
• DECOMPOSITION
• SHIFT REGISTERS
• STOCHASTIC PROCESSES

Subject Categories:

• Computer Programming and Software
• Computer Hardware

Distribution Statement:

APPROVED FOR PUBLIC RELEASE