Transcript Chapter 2
Chapter 2: Computer Systems Computer Hardware The physical pieces of a computer system, such as a central processing unit (CPU), a microprocessor, a printer, a disk drive, or a modem Something you can touch Evolution of Computer Systems First Generation - 1946-1959 - vacuum tubes, rotating drum memory Second Generation - 1959-1964 transistors, magnetic core memory Third Generation - 1964-1979 integrated circuits, semiconductor memory, operating systems Fourth Generation - 1979-present - LSI and VLSI circuits, communications Basic Components of Computers Input/Output Computer Memory Arithmetic/Logical Unit Computer Files Control Unit CPU Control Unit Input Arithmetic/ Logical Unit Memory Files Output Stored Program Concept The concept of preparing a precise list of exactly what the computer is to do (this list is called a program), loading or storing this program in the memory of the computer, and then letting the control unit carry out the program at electronic speed. The program must be in a form that the control unit of the computer has been built to understand. Types of Computers Microcomputers Workstations Midrange computers (minicomputers) Mainframes Supercomputers These categories are listed in general order of increasing size, power, and cost Network Computer / NetPC Basic idea of both is a stripped down, less expensive PC for users who will always be connected to a network Network Computer would have minimal memory, processor, disk storage (perhaps no hard drive) NetPC (Microsoft) would be more powerful so that Windows could be implemented locally RISC Chips Reduced Instruction Set Computing By working with a reduced instruction set, designers were able to create a smaller, faster chip than had been possible previously Basis for HP 9000, IBM RISC/6000, Sun SPARCsystem, other high-powered workstations Cache Memory Very high speed, high cost storage unit Used as an intermediary between pieces of the computer that operate at quite different speeds Example -- between the control unit (microprocessor) and main memory Example -- between disk drive and data channel Controller A hardware device to link input/output or file devices to the CPU and memory of large computer systems A highly specialized processor which manages the operation of its attached devices to free the CPU from these tasks Data Channel A specialized input/output processor (a computer) that takes over the function of device communication from the CPU The role of the data channel is to correct for the speed mismatch between the slow peripheral devices and the very fast CPU Symmetric Multiprocessor Multiprocessor machine in which all of the processors (CPUs) are identical, with each processor operating independently of the others This design technique is used in most mainframes and an increasing number of midrange machines Parallel Processor (PP) A multiprocessor configuration (multiple CPUs installed as part of a single computer system) designed to give a separate piece of the same program to each of the processors so that work on the program can proceed in parallel on the separate pieces Massively Parallel Processor (MPP) A parallel processing computer with some large number of parallel processors 32 or more parallel CPUs if the different CPUs are capable of performing different instructions at the same time 1000 or more parallel CPUs if the different CPUs must all carry out the same instruction at the same time Changing Nature of Hardware Decreasing price/performance ratio -- faster and cheaper Increasing miniaturization Increasing multimedia (data, video, sound) More plug-and-play and portability Greater management complexity due to linking of distributed, cross-platform technologies The Information Technology Industry The Information Technology industry is the largest industry in the world, by far. Let’s look at the primary players. Top IS Companies in the World, 1996 1996 Rank Company Country 1996 IS Reve nue 1 IBM U.S. $75,947 2 Hewlett-Packard U.S. 31,398 3 Fujitsu Japan 29,717 4 Compaq Computer U.S. 18,109 5 Hitachi Japan 15,242 6 NEC Japan 15,092 7 EDS U.S. 14,441 8 Toshiba Japan 14,050 9 Digital Equipment U.S. 13,610 10 Microsoft U.S. 9,435