A CLOSER LOOK AT MICROPROCESSORS THAT HAVE SHAPED THE DIGITAL WORLD Christopher U. Ngene1 Student member IEEE, Manish Kumar Mishra2 1Computer Engineering Faculty, Kharkov National University of Radioelectronics, Kharkov, Ukraine [email protected]. 2Department of Computer Engineering University of Maiduguri, Nigeria; [email protected] 11 The fate of both Intel and Microsoft was dramatically Abstract – If you have been following the development in the changed in 1981 when IBM introduced the IBM PC, which microprocessor world you would attest to the fact that things was based on a 4.77MHz Intel 8088 16-bit processor running have dramatically changed since the introduction of the first the Microsoft Disk Operating System (MS-DOS) 1.0. Was world acclaimed microprocessor Intel 4004 in 1971. What were there any one chip that propelled Intel into the Fortune 500? the changes that have been made to these processors that have actually improved our lots, especially how we perceive the world Intel says there was: the 8088 [6]. Since that fateful decision around us and improve our productivity at work? In this study, was made, computers became affordable and found their we investigate different general purpose processors with a view ways into our homes. The focus of this paper is on Intel and to enlightening consumers and enthusiasts alike, determine AMD processors. Even at that we have discussed selected which of the myriads of processors will be most appropriate for number of processors that have made their marks in the their tasks and the choice of which makes more economic sense. industry. The obvious reason for this selective approach is We have been able to explore in relative detail that processor because there are myriads of processors in the inventory of speed is not the only determinant of processor performance but these vendors which the limited space at our disposal will not of most significant is the architecture. This study reveals that be enough to accommodate. new technology is not the only factor that determines whether a new processor is actually new, but most importantly marketing Available publications on microprocessors have focused considerations have been the driving force. mainly on the historical development, specific processor reviews and benchmarking [1][2][18]. We agree that these are necessary. But numerous users of these processors may I. INTRODUCTION not quite appreciate some of the technical jargons employed in some of these publications. With respect to the above this Since the introduction of the first commercial integrated paper has taken a wider perspective to give our readers a circuit in 1961 and the introduction of the first holistic view. This has dictated the approach we have taken microprocessor in 1971, the semiconductor industry has and have encapsulated all vital information regarding experienced a healthy growth. Anyone involved in electronic processor within the pages of this paper. In this paper we design or electronic design automation (EDA), marketing or have given a brief historical background of microprocessors analysis of electronic devices knows that things are becoming and how the Moore’s law has been holding out as a result of evermore complex as the years go by and microprocessors innovations in chip fabrication enabling smaller and smaller are no exception to this rule. By comparison today’s feature sizes. The rest of this paper is presented as follows: microprocessors are more complex than the 1960’s and ‘70s section 2 presents some historical backgrounds on the mainframe’s central processing units. Most importantly these development of transistors, integrated circuits and processors outperform those mainframe CPUs and are subsequently microprocessors. In this section we have also cheaper and affordable. Architectures have also evolved to looked at the basic processor architectures. Section 3 presents the extent that we no longer talk about CISC or RISC but a the different types of processors and microprocessor feature combination of both. Other architectures that enhance trends. Special purpose processors – microcontrollers, performance like EPIC (Explicitly Parallel Instruction graphic and digital signal processors were discussed, but a computing) based on VLIW in conjunction with pipelining, detailed description of these processors have been left out for super-scaling and hyper-threading have boosted performance future work. Section 4 presents methods of chip fabrication, to unimaginable level. foundries, process yield and process technologies and an evaluation of the relationships between die sizes, lithography and transistor count per die. 1 Manuscript received November 3, 2009. Christopher U. Ngene is with the Kharkov National Uuniversity of 2. BACKGROUND INFORMATION Radioelectronics, Computer Engineering Faculty, Lenin Prosp., 14, Kharkov, 61166, Ukraine (corresponding author, phone: +38057-7021326), Before we proceed further a little background would [email protected]. suffice in order to appreciate where we are now by knowing Manish Kumar Mishra is with Department of Computer Engineering University of Maiduguri, Nigeria; [email protected] where we came from. The development of computer systems is closely tied with processors and subsequently R&I, 2009, No4 41 microprocessors. Processor (Central Processing Unit - CPU) language. The discovery of transistor by three bell laboratory in conjunction with the memory is the brain of the computer. scientists - J. Bardeen, H. W. Brattain, and W. Shockley Data processing (arithmetic and logic operations take place in launched the Second generation processors. Transistors the CPU). Early computers which were mainly mainframes revolutionised electronics in general and computers in have very large CPUs. Early CPUs were implemented as particular. Transistors were much smaller than vacuum tubes, discrete components and numerous small integrated circuits consumed less energy, faster switching and more reliable. (ICs) on one or more circuit boards. Microprocessors, on the Programming of the CPU was done in assembly languages other hand, are CPUs manufactured on a very small number (symbolic languages) and followed by high level languages of ICs; usually just one. The overall smaller CPU size as a such as FORTRAN and COBOL. Standardization trend result of being implemented on a single die means faster generally began in the era of discrete transistor CPUs. With switching time because of physical factors like decreased gate this improvement more complex and reliable CPUs were built parasitic capacitance. Prior to the advent of machines that onto one or several printed circuit boards containing resemble today's CPUs, computers such as the ENIAC had to individual components. After the deployment of transistors as be physically rewired in order to perform different tasks. a switching element, CPUs were still large and occupies These machines are often referred to as "fixed-program several circuit boards. The needs to reduce the size of computers," since they had to be physically reconfigured in components were primary preoccupation of engineers and order to run a different program. Since the term "CPU" is scientists. A method of manufacturing many transistors in a generally defined as a software (computer program) compact space was developed. This method is known as execution device, the earliest devices that could rightly be Integrated Circuit (IC). An IC is a complete electronic circuit called CPUs came with the advent of the stored-program on a small chip of silicon. Beginning in 1965 ICs began to computer. CPU deals with discrete states and thus employs replace transistors in CPUs. In 1959, Jack Kilby and Robert switching elements for change of states. Before the discovery Noyce independently invented a means of fabricating of transistors, electrical relays and vacuum tubes (thermionic multiple transistors on a single slab of semiconductor valves) were commonly used as switching elements. The material. electromechanical relays and vacuum tubes have the 2.2 Scale of Integration problems of contact bounce and heat respectively. They generally have a slow switching capability. They are Dimensions on an IC are measured in units of considered to be very unreliable for the above reasons. Tube micrometers, with one micrometer (1 µm) being one computers like EDVAC are generally faster than millionth of a meter. To serve as a reference point, a human electromechanical computer (Harvard Mark I) but are less hair is roughly 100 µm in diameter. Each year, researchers reliable. EDVAC tended to average eight hours between and engineers have been finding new ways to steadily reduce failures, whereas relay computers (Harvard Mark I) failed these feature sizes to pack more transistors into the same rarely. silicon area. There are different levels of integration. This has to do with the number of digital components that are placed 2.1 Evolution and Direction of Development on a single chip. The early ICs contained only one building Let us start by examining the different switching elements block (logic gates) such as AND gates etc. CPUs based on and subsequent technologies that characterises the this sort of IC are known as Small Scale Integration (SSI) generations of microprocessor. Vacuum tubes and devices. Such ICs contained tens of transistors. To build an electromechanical relays were used in the first generation entire CPU out of SSI ICs required thousands of individual Processors. One other important drawback of these early chips,