LectureNotesPartOne - Lecture Notes Section One: There are...

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Lecture Notes Section One: There are two major approaches to the design of computer control units: Hardwired: faster but less flexible Microprogrammed: slower but easier to design, debug and modify We will be discussing various aspects of this throughout this course. We will also discuss the evolution of computer systems/ In the early days of computer design, not that many years ago, each new system was designed from scratch. This meant that if you bought a new computer, all of your previously developed software was unusable and had to be redone. IBM changed all of this in 1964, with the introduction of their system 360 series of computers. Each new system contained in its new instruction set, the instruction set of its predecessor. Therefore existing software would run on the new machine with little or no modification. This old software might not take advantage of some of the new system’s capabilities but it would run thus saving time and development costs for new software. This started a trend in computer design which is obvious today in our use of PC’s with Intel’s 80x86 and Pentium processors and compatible clones from other manufactures. The instruction set of each new Intel chip in this series is a superset containing all of the instructions of its predecessor. Another issue that we will address is that of the effects of advances in hardware technology and its effect on system design. In the early days of computer systems: hardware was very expensive, but programmers were relatively inexpensive. Today, hardware is inexpensive and programmers are relatively more expensive, so design philosophy and programming philosophy has changed. One result of these technological advances is that, for a couple of thousand dollars, you can have a PC on your desk that is many thousands of times faster than the mainframes of twenty-five years ago at less than one percent of the cost of the older systems. These older systems often required large rooms with tons of air conditioning in order to function. Historically, computers have fallen into one of three categories:
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This note was uploaded on 02/10/2012 for the course CSC 520 taught by Professor Simmons during the Fall '07 term at S. Alabama.

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LectureNotesPartOne - Lecture Notes Section One: There are...

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