Computer Busses

William Buchanan

• Publisher: Butterworth-Heinemann
• Year: 2000
• Print ISBN: 9780340740767
• eBook ISBN: 9780080529721
• Topic: Design
• Subtopic: Data Transmission Systems

As more and more equipment is interface or'bus' driven, either by the use of controllers or directly from PCs, the question of which bus to use is becoming increasingly important both in industry and in the office. 'Computer Busses' has been designed to help choose the best type of bus for the particular application. There are several books which cover individual busses, but none which provide a complete guide to computer busses. The author provides a basic theory of busses and draws examples and applications from real bus case studies. Busses are analysed using from a top-down approach, helping the undergraduate electrical or computer engineer to chose the right type of bus for their particular application. This book is essential reading for students of software engineering and electronic design, as well as for those working in disciplines such as production engineering or process control. It will also be a handy reference book for professional engineers, systems designers, consultants and those working in technical support. - Provides a complete guide to computer busses - Contains application-specific programme examples - Plenty of real-life case studies

1

Introduction

1.1 Pre-PC Development

One of the first occurrences of computer technology occurred in the USA in the 1880s. It was due to the American Constitution demanding that a survey is undertaken every 10 years. As the population in the USA increased, it took an increasing amount of time to produce the statistics. By the 1880s, it looked likely that the 1880 survey would not be complete until 1890. To overcome this, Herman Hollerith (who worked for the Government) devised a machine which accepted punch cards with information on them. These cards allowed a current to pass through a hole when there was a hole present.

Hollerith’s electromechanical machine was extremely successful and used in the 1890 and 1900 Censuses. He even founded the company that would later become International Business Machines (IBM): CTR (Computer Tabulating Recording). Unfortunately, Hollerith’s business fell into financial difficulties and was saved by a young salesman at CTR, named Tom Watson, who recognized the potential of selling punch card-based calculating machines to American business. He eventually took over the company Watson, and, in the 1920s, he renamed it International Business Machines Corporation (IBM). After this, electromechanical machines were speeded up and improved. Electromechnical computers would soon lead to electronic computers, using valves.

The first electronic computers were developed, independently, in 1943; these were the ‘Harvard Mk I’ and Colossus. Colossus was developed in the UK and was used to crack the German coding system (Lorenz cipher), whereas ‘Harvard Mk I’ was developed at Harvard University and was a general-purpose electromechanical programmable computer. These led to the first generation of computers which used electronic valves and used punched cards for their main, non-volatile storage.

The world’s first large electronic computer (1946), containing 19 000 values was built at the University of Pennsylvania by John Eckert during World War II. It was called ENIAC (Electronic Numerical Integrator and Computer) and it ceased operation in 1957. By today’s standards, it was a lumbering dinosaur and by the time it was dismantled it weighed over 30 tons and spread itself over 1500 square feet. Amazingly, it also consumed over 25 kW of electrical power (equivalent to the power of over 400, 60 W light bulbs), but could perform over 100 000 calculations per second (which is reasonable, even by today’s standards). Unfortunately, it was unreliable, and would only work for a few hours, on average, before a valve needed to be replaced. Faultfinding, though, was easier in those days, as a valve, which was working, would not glow, and would be cold to touch.

Valves were fine and were used in many applications, such as in TV sets and radios, but they were unreliable and consumed great amounts of electrical power, mainly to the heating element on the cathode. By the 1940s, several scientists at the Bell Laboratories were investigating materials called semiconductors, such as silicon and germanium. These substances only conducted electricity moderately well, but when they where doped with impurities their resistance changed. From this work, they made a crystal called a diode, which worked like a valve, but had many advantages, including the fact that it did not require a vacuum and was much smaller. It also worked well at room temperatures, required little electrical current and had no warm-up time. This was the start of microelectronics.

One of the great revolutions of all time occurred on December 1948 when William Shockley, Walter Brattain, and John Bardeen at the Bell Labs produced a transistor that could act as a triode. It was made from a germanium crystal with a thin p-type section sandwiched between two n-type materials. Rather than release its details to the world, Bell Laboratories kept its invention secret for over seven months so that they could fully understand its operation. They soon applied for a patent for the transistor and, on 30 June 1948, they finally revealed the transistor to the world. Unfortunately, as with many other great inventions, it received little public attention and even less press coverage (the New York Times gave it 4½ inches on page 46). It must be said that few men have made such a profound change on the world, and Shockley, Brattain, and Bardeen were deservedly awarded the Nobel Prize in 1956. To commercialize on his success, Shockley, in 1955, founded Shockley Semiconductor. Then in 1957, eight engineers decided they could not work within Shockley Semiconductor and formed Fairchild Semiconductors, which would become one of the most inventive companies in Silicon Valley. Unfortunately, most of the time Fairchild Semiconductors did not fully exploit its developments, and was more of an incubator for many of the innovators in the electronics industry. Around the same time, Kenneth Olsen founded the Digital Equipment Corporation (DEC), who would go on to become one of the key companies in the computer industry, along with IBM.

Previously, in 1952, GW Dummer, a radar expert from Britain’s Royal Radar Establishment had presented a paper proposing that a solid block of materials could be used to connect electronic components, without connecting wires. This would lay the foundation of the integrated circuit.

Transistors were initially made from germanium, which is not a robust material and cannot withstand high temperatures. The first company to propose the use of silicon transistors was a geological research company named Texas Instruments (which had diversified into transistors). Then, in May 1954, Texas Instruments started commercial production of silicon transistors. Soon many companies were producing silicon transistors and, by 1955, the electronic valve market had peaked, while the market for transistors was rocketing. The larger electronic valve manufacturers, such as Western Electric, CBS, Raytheon and Westinghouse failed to adapt to the changing market and quickly lost their market share to the new transistor manufacturing companies, such as Texas Instruments, Motorola, Hughes and RCA.

In July 1958, at Texas Instruments, Jack St. Clair Kilby proposed the creation of a monolithic device (an integrated circuit) on a single piece of silicon. Then, in September, he produced the first integrated circuit, containing five components on a piece of germanium that was half an inch long and was thinner than a toothpick.

The following year, Fairchild Semiconductor filed for a patent for the planar process of manufacturing transistors. This process made commercial production of transistors possible and led to Fairchild’s introduction, in two years, of the first commercial integrated circuit. Within a few years, transistors were small enough to make hearing aids that fitted into the ear, and soon within pacemakers. Companies, such as Sony, started to make transistors operate over higher frequencies and within larger temperature ranges. Eventually they became so small that many of them could be placed on a single piece of silicon. These were referred to as microchips and they started the microelectronics industry. The first two companies who developed the integrated circuit, were Texas Instruments and Fairchild Semiconductor. At Fairchild Semiconductor, Robert Noyce constructed an integrated circuit with components connected by aluminium lines on a silicon-oxide surface layer on a plane of silicon. He then went on to lead one of the most innovate companies in the world, the Intel Corporation.

After ENIAC, progress was fast in the computer industry and, by 1948, small electronic computers were being produced in quantity within five years (2000 were in use), in 1961 it was 10 000, 1970 100 000. IBM, at the time, had a considerable share of the computer market, so much so that a complaint was filed against them alleging monopolistic practices in its computer business, in violation of the Sherman Act. By January 1954, the US District Court made a final judgment on the complaint against IBM. For this, a ‘consent decree’ was then signed by IBM, which placed limitations on how IBM conducts business with respect to ‘electronic data processing machines’.

In 1954, the IBM 650 was built and was considered the workhorse of the industry at the time (which sold about 1000 machines, and used valves). In November 1956, IBM showed how innovative they were by developing the first hard disk, the RAMAC 305. It was towering by today’s standards, with 50 two-foot diameter platters, giving a total capacity of 5 MB. Around the same time, the Massachusetts Institute of Technology produced the first transistorised computer: the TX-O (Transistorized Experimental computer). Seeing the potential of the transistor, IBM quickly switched from valves to transistors and, in 1959, they produced the first commercial transistorised computer. This was the IB...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright page
• Preface
• 1: Introduction
• 2: Busses, Interrupts and PC Systems
• 3: Interfacing Standards
• 4: PCI Bus
• 5: Motherboard Design
• 6: IDE and Mass Storage
• 7: SCSI
• 8: PCMCIA
• 9: USB and Firewire
• 10: Games Port, Keyboard and Mouse
• 11: AGP
• 12: Fibre Channel
• 13: RS-232
• 14: RS-422, RS-423 and RS-485
• 15: Modems
• 16: Parallel Port
• 17: Enhanced Parallel Port
• 18: Modbus
• 19: Fieldbus
• 20: WorldFIP
• 21: CAN bus
• 22: IEEE-488, VME and VXI
• 23: TCP/IP
• 24: TCP and UDP
• 25: Networks
• 26: Ethernet
• 27: RS-232 Programming using Visual Basic
• 28: Interrupt-driven RS-232
• A: PC Processors
• B: VESA VL-Local Bus
• C: Modem Codes
• D: Redundancy checking
• E: ASCII Character Code
• F: Quick Reference
• G: ISDN
• H: Microsoft Windows
• I: HDLC
• J: Example WinSock Code for Visual Basic
• Index