Chapter 17 Looking “Under the Hood”

Practical PC 6th Edition Chapter 17 Getting Started FAQs: 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? How does software tie into chips, codes, and circuits? Practical PC 6th 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 Practical PC 6th 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 process called “storing data” Practical PC 6th Edition Chapter 17

How does a computer work? Practical PC 6th Edition Chapter 17

What do RAM and processing circuitry look like? RAM and processing circuitry are contained in “chips” inside the 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 Practical PC 6th 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 Practical PC 6th Edition Chapter 17

What do RAM and processing circuitry look like? Practical PC 6th 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 Practical PC 6th 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 and Unicode 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 Practical PC 6th Edition Chapter 17

Does a computer use the same code for all types of data? Practical PC 6th 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 using 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 Practical PC 6th Edition Chapter 17

How does software tie into chips, codes, and circuits? Practical PC 6th Edition Chapter 17

Hardware: Microprocessors Microprocessor is a single integrated circuit Most computers 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 x86 microprocessors 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 Practical PC 6th 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 Most of today’s microprocessors have multi-level caches L1, L2, or L3 caches Accelerated front side bus; fast version will move data quickly and will allow the processor to work at full capacity HyperTransport and QuickPath Practical PC 6th 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 Word size: refers to the number of bits that a microprocessor can manipulate at one 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 Practical PC 6th Edition Chapter 17

Hardware: Microprocessors Benchmark tests measuring processor performance fall into categories: Multimedia benchmarks measure performance when processing multimedia data Integer benchmarks measure processing efficiency for integer data Floating-point benchmarks measure performance for numbers stored in a “floating point” format used in 3-D graphics, computer-aided design, and many computer games Practical PC 6th 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? Practical PC 6th Edition Chapter 17