Chapter 1 Introduction Chapter 1 Objectives Know the difference between computer organization and computer architecture Understand units of measure common to computer systems Appreciate the evolution of computers Understand the computer as a layered system Be able to explain the von Neumann architecture and the function of basic computer components 2 1 1 Overview Why study computer organization and architecture Design better programs including system software such as compilers operating systems and device drivers Optimize program behavior Evaluate benchmark computer system performance Understand time space and price tradeoffs 3 1 1 Overview Computer organization Encompasses all physical aspects of computer systems E g circuit design control signals memory types How does a computer work Computer architecture Logical aspects of system implementation as seen by the programmer E g instruction sets instruction formats data types addressing modes How do I design a computer 4 1 2 Computer Components There is no clear distinction between matters related to computer organization and matters relevant to computer architecture Principle of Equivalence of Hardware and Software Anything that can be done with software can also be done with hardware and anything that can be done with hardware can also be done with software Assuming speed is not a concern 5 1 2 Computer Components At the most basic level a computer is a device consisting of three pieces A processor to interpret and execute programs A memory to store both data and programs A mechanism for transferring data to and from the outside world 6 1 3 An Example System Consider this advertisement a C L1 e ch z MH MB I C P US B What does it all mean 7 1 3 An Example System Measures of capacity and speed Kilo K 1 thousand 103 and 210 Mega M 1 million 106 and 220 Giga G 1 billion 109 and 230 Tera T 1 trillion 1012 and 240 Peta P 1 quadrillion 1015 and 250 Exa E 1 quintillion 1018 and 260 Zetta Z 1 sextillion 1021 and 270 Yotta Y 1 septillion 1024 and 280 Whether a metric refers to a power of ten or a power of two typically depends upon what is being measured 8 1 3 An Example System Hertz clock cycles per second frequency 1MHz 1 000 000Hz Processor speeds are measured in MHz or GHz Byte a unit of storage 1KB 210 1024 Bytes 1MB 220 1 048 576 Bytes Main memory RAM is measured in MB Disk storage is measured in GB for small systems TB for large systems 9 1 3 An Example System Measures of time and space Milli m 1 thousandth 10 3 Micro 1 millionth 10 6 Nano n 1 billionth 10 9 Pico p 1 trillionth 10 12 Femto f 1 quadrillionth 10 15 Atto a 1 quintillionth 10 18 Zepto z 1 sextillionth 10 21 Yocto y 1 septillionth 10 24 10 1 3 An Example System Millisecond 1 thousandth of a second Hard disk drive access times are often 10 to 20 milliseconds Nanosecond 1 billionth of a second Main memory access times are often 50 to 70 nanoseconds Micron micrometer 1 millionth of a meter Circuits on computer chips are measured in microns 11 1 3 An Example System We note that cycle time is the reciprocal of clock frequency A bus operating at 133MHz has a cycle time of 7 52 nanoseconds 133 000 000 cycles second 7 52ns cycle Now back to the advertisement 12 1 3 An Example System The microprocessor is the brain of the system It executes program instructions This one is a Pentium Intel running at 4 20GHz A system bus moves data within the computer The faster the bus the better This one runs at 400MHz 13 1 3 An Example System Computers with large main memory capacity can run larger programs with greater speed than computers having small memories RAM is an acronym for random access memory Random access means that memory contents can be accessed directly if you know its location Cache is a type of temporary memory that can be accessed faster than RAM 14 1 3 An Example System This system has 256MB of fast synchronous dynamic RAM SDRAM and two levels of cache memory the level 1 L1 cache is smaller and probably faster than the L2 cache Note that these cache sizes are measured in KB 15 1 3 An Example System Hard disk capacity determines the amount of data and size of programs you can store This one can store 80GB 7200 RPM is the rotational speed of the disk Generally the faster a disk rotates the faster it can deliver data to RAM There are many other factors involved 16 1 3 An Example System ATA stands for advanced technology attachment which describes how the hard disk interfaces with or connects to other system components A CD can store about 650MB of data This drive supports rewritable CDs CD RW that can be written to many times 48x describes its speed 17 1 3 An Example System Ports allow movement of data between a system and its external devices This system has ten ports 18 1 3 An Example System Serial ports send data as a series of pulses along one or two data lines Parallel ports send data as a single pulse along at least eight data lines USB Universal Serial Bus is an intelligent serial interface that is self configuring It supports plug and play 19 1 3 An Example System System buses can be augmented by dedicated I O buses PCI peripheral component interface is one such bus This system has three PCI devices a video card a sound card and a data fax modem 20 1 3 An Example System The number of times per second that the image on a monitor is repainted is its refresh rate The dot pitch of a monitor tells us how clear the image is This one has a dot pitch of 0 24mm and a refresh rate of 75Hz The video card contains memory and programs that support the monitor 21 1 3 An Example System Throughout the remainder of this book you will see how these components work and how they interact with software to make complete computer systems This statement raises two important questions What assurance do we have that computer components will operate as we expect And what assurance do we have that computer components will operate together 22 1 4 Standards Organizations There are many organizations that set computer hardware standards to include the interoperability of computer components Throughout this book and in your career you will encounter many of them Some of the most important standardssetting groups are 23 1 4 Standards Organizations The Institute of Electrical and Electronic Engineers IEEE Promotes the interests of the worldwide electrical engineering community Establishes standards for computer components data representation and signaling protocols among many other things 24 1 4