Chapter 17 Looking “Under the Hood”

2Practical PC 5 th Edition Chapter 17 Getting Started In this Chapter, you will learn: − How does a computer work − What do RAM and processing circuitry look like − How does data get into chips − Does a computer use the same code for all types of data

3Practical PC 5 th Edition Chapter 17 Getting Started In this Chapter, you will learn (continued): − How does software tie into chips, codes, and circuits − About Hardware: Microprocessors

4Practical PC 5 th Edition Chapter 17 How does a computer work? A computer works by manipulating data – Data refers to the symbols that describe people, events, things, and ideas – A computer works with data in four ways Accepting input data Processing data Producing output data Storing data – Input is the data that goes into a computer The computer puts data into RAM (Random Access Memory), a temporary holding area for data

5Practical PC 5 th Edition Chapter 17 How does a computer work? RAM holds data and tells the computer what to do A computer’s circuitry reads data and processes it Processing data means manipulating it in some way, such as performing a calculation An instruction indicates that data should be transferred from RAM to a printer, modem, or display screen as output Data sent to the hard disk drive is done using a a process called “storing data”

6Practical PC 5 th Edition Chapter 17 How does a computer work? Input data arrives in RAM and is processed

7Practical PC 5 th Edition Chapter 17 What do RAM and processing circuitry look like? RAM and processing circuitry are contained in “chips” inside PC – Chip: nickname for an integrated circuit – Integrated circuit: thin slice of silicon etched with microscopic circuitry – Microprocessor chip: carries out most of the processing work on PC – RAM chips: temporarily hold data – ROM chips: hold the instructions for PC to boot up

8Practical PC 5 th Edition Chapter 17 What do RAM and processing circuitry look like? Chip is housed in small, black, rectangular chip carrier Circuit board contains electrical pathways that allow data to travel between chips In a typical PC, a large circuit board houses the microprocessor chip, ROM chips, and support chips Series of RAM chips are connected to a small circuit board called a memory module

9Practical PC 5 th Edition Chapter 17 What do RAM and processing circuitry look like? PC System Board

10Practical PC 5 th Edition Chapter 17 How does data get into chips? PC works with data converted into code and then into electronic signals that travel through circuits on chips and circuit boards – Computer codes are based ones and zeros – Each 1 or 0 is a bit (short for binary digit) – Eight bits form a byte Data is coded to transmit electronically As data is gathered, processed, stored, and transmitted, special controller chips constantly convert it from one type of signal to another

11Practical PC 5 th Edition Chapter 17 Does a computer use the same code for all types of data? Computers use different codes for different types of data – Text data: ASCII, extended ASCII, ANSI, Unicode, or EBCDIC codes – Numbers for calculations: binary number system – Bitmap images: binary color code for each dot – Recorded sound: binary number represents height of wave sample Codes share characteristics – Digital: converts data into a finite set of numbers – Binary: uses only 0s and 1s – Fixed length: use the same number of bits to represent each data item

12Practical PC 5 th Edition Chapter 17 Does a computer use the same code for all types of data? ASCII code: Digital, Binary, and Fixed Length

13Practical PC 5 th Edition Chapter 17 How does software tie into chips, codes, and circuits? Software is a collection of programs or program modules containing a list of instructions – Instructions are written in a computer programming language – Today’s programming languages use English-like words – English-like words must be converted into a machine language of 1s and 0s Compiling is the process of converting English-like words into 1s and 0s – Compiling creates executable EXE files

14Practical PC 5 th Edition Chapter 17 Hardware: Microprocessors Microprocessor is a single integrated circuit Microcomputer is a type of computer that uses a microprocessor as its main processing unit, such as your PC Most microcomputers contain x86 microprocessors − Able to work with the x86 instruction set − Intel is the original x86 chipmaker and is still the largest − Both Intel and AMD offer chips with speeds over 3 GHz Clock speed is measured in megahertz (MHz) or gigahertz (GHz) −One MHz is 1 million cycles per second and one GHz is 1 billion cycles per second −Clock speed is analogous to how fast you pedal a bike. Faster cycles mean faster computer processing

15Practical PC 5 th Edition Chapter 17 Hardware: Microprocessors Several factors can affect the speed at which a microprocessor processes instructions − Instructions per clock cycle: Processors that execute multiple instructions per clock cycle are referred to as superscalar − Cache memory is data-holding circuitry that can be accessed faster than RAM Level 1 cache is on the microprocessor chip Level 2 cache is on a separate chip − Accelerated front side bus; fast version will move data quickly and will allow the processor to work at full capacity HyperTransport is a technique to accelerate the rate data travels on the front side bus

16Practical PC 5 th Edition Chapter 17 Hardware: Microprocessors Several factors can affect the speed at which a microprocessor processes instructions (continued) − Extended instruction sets: some processors have this feature to speed up certain types of processing − Multi-core architecture: multi-core processor is a single microprocessor chip with circuitry that allows it to process more than one instruction at a time Benchmark test is a set of standard processing tasks that measure the performance of computer hardware and software − Microprocessor benchmark tests measure processor speed

17Practical PC 5 th Edition Chapter 17 Hardware: Microprocessors Benchmark tests measuring processor performance fall into categories: − Multimedia benchmarks measure performance when processing multimedia data − Integer benchmarks measure performance when processing words and numbers used in word processing, presentation, spreadsheet, and database applications − Floating-point benchmarks measure performance for numbers stored in a special “floating point” format used in 3-D graphics, computer- aided design, and many computer games − Real-world performance benchmarks measure how well a computer executes a predefined set of tasks while running word processing, spreadsheet, and other productivity software

18Practical PC 5 th Edition Chapter 17 Who invented the first electronic digital computer? What do you think? – Do you think the judge made the right decision, despite the fact that Atanasoff never filed for a patent? – Do you think that Zuse, instead of Atanasoff, should be declared the inventor of the first electronic digital computer? – Do you think that the computer industry would be different today if Sperry Rand had won its patent case?

19Practical PC 5 th Edition Chapter 17 Chapter Summary You should now: − Understand how a computer works − Know what RAM and processing circuitry look like − Understand how data gets into chips − Know if a computer uses the same code for all types of data

20Practical PC 5 th Edition Chapter 17 Chapter Summary You should now be able to (continued): − Know how software ties into chips, codes, and circuits − Understand Microprocessors