ABSTRACT
Computer systems are made up of both hardware and software parts, and over the years, the percentage of overall computer system cost spent on the hardware part has changed quite dramatically. For example, in 1955 the hardware part accounted for about 80% of overall computer system cost; by 1980, the cost of the hardware part had decreased to around 10% [1, 2]. Nowadays, the cost of software is a very important component of the overall computer system cost. More specifically, the cost of software plays a crucial role in the computer system life-cycle cost.
