The technological advances witnessed in the computer industry are the result of a long chain of immense and successful efforts made by two major forces. These are the academia, represented by university research centers, and the industry, represented by computer companies. It is, however, fair to say that the current technological advances in the computer industry owe their inception to university research centers. In order to appreciate the current technological advances in the computer industry, one has to trace back through the history of computers and their development.

Fundamentals of computer organisation and architecture

The objective of such historical review is to understand the factors affecting computing as we know it today and hopefully to forecast the future of computation. A great majority of the computers of our daily use are
known as general purpose machines. These are machines that are built with no specific application in mind, but rather are capable of performing computation needed by a diversity of applications. These machines are to be distinguished from those built to serve (tailored to) specific applications.

The latter are known as special purpose machines.Computer systems have conventionally been defined through their interfaces at a number of layered abstraction levels, each providing functional support to its predecessor. Included among the levels are the application programs, the high-level languages, and the set of machine instructions. Based on the interface between different levels of the system, a number of computer architectures can be defined.

Internal Hardware: Upgrade or Replace

The interface between the application programs and a high-level language is referred to as a language architecture. The instruction set architecture defines the interface between the basic machine instruction set and the runtime and I/O control. A different definition of computer architecture is built on four basic viewpoints. These are the structure, the organization, the implementation, and the performance.

In this definition, the structure defines the interconnection of various hardware components, the organization defines the dynamic interplay and management of the various components, the implementation defines the detailed design of hardware components, and the performance specifies the behavior of the computer system.


Computer architects have always been striving to increase the performance of their architectures. This has taken a number of forms. Among these is the philosophy that by doing more in a single instruction, one can use a smaller number of instructions to perform the same job. The immediate consequence of this is the need for fewer memory read/write operations and an eventual speedup of operations.

It was also argued that increasing the complexity of instructions and the number of addressing modes has the theoretical advantage of reducing the “semantic gap” between the instructions in a high-level language and those in the low-level (machine) language. A single (machine) instruction to convert several binary coded decimal (BCD) numbers to binary is an example for how complex some instructions were intended to be.

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The huge number of addressing modes considered (more than 20 in the VAX machine) further adds to the complexity of instructions. Machines following this philosophy have been referred to as complex instructions set computers (CISCs). Examples of CISC machines include the Intel PentiumTM, the Motorola MC68000TM, and the IBM & Macintosh PowerPCTM.


Computer technology has shown an unprecedented rate of improvement. This includes the development of processors and memories. Indeed, it is the advances in technology that have fueled the computer industry. The integration of numbers of transistors (a transistor is a controlled on/off switch) into a single chip has increased from a few hundred to millions.

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This impressive increase has been made possible by the advances in the fabrication technology of transistors. The scale of integration has grown from small-scale (SSI) to medium-scale (MSI) to large-scale (LSI) to very large-scale integration (VLSI), and currently to waferscale integration (WSI) the typical numbers of devices per chip in each of these technologies.

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