xp practical pc, 3e chapter 16 1 looking “under the hood”

Practical PC, 3eChapter 16

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Chapter 16

Looking “Under the Hood”


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XPLooking “Under the Hood”

• In this Chapter, you will learn:– How a computer works

– What RAM and processing circuitry looks like

– How data gets into chips

– What code computers use for different kinds of data

– How software ties into chips, codes and circuits

– How to find the technical specifications for your PC

– About microprocessors


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XPHow a computer works

• Computers work on manipulating data.• Data is all of the information that the computer

uses to do tasks.• Computers:

– Accept data as input

– Process the data

– Produce output data

– Store data for later use


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• Data coming into a computer is called input.• Input comes from the keyboard, hard drive,

internet, floppy disks, mouse, etc. and is put into RAM.

• Computer software processes the data in RAM.• Then the data is either stored or becomes output to

a device such as a printer, modem, or display screen.


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A simple computer diagram


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XPLooking at RAM and processing circuitry

• An integrated circuit in a computer is on a microchip nicknamed “chip.”

• An integrated circuit is microscopic circuitry that has been etched on a very thin slice of silicon.

• There are many types of chips. For instance:– Microprocessor chips do the main computer processing

– RAM chips – temporarily store data and instructions

– ROM chips – hold boot up instructions


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• Chips are housed in a chip carrier which is soldered or plugged into a circuit board.

• The main circuit board, called a motherboard, connects the chips together with electrical pathways and houses the primary function chips.

• RAM chips are connected to the memory module, a small circuit board and are also connected to the motherboard.


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The inside of your computer

Graphics card Memory module

Microprocessor

Rom

Battery

Slots for sound card, modem or video capture card


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XPHow data gets into chips

• As data comes into your computer, it is converted into a series of codes - binary digits.

• Binary consists of only 0s and 1s and every character can be represented by a series of these binary digits (bits).

• A byte (or character) is eight bits.• 0s and 1s are stored like a light switch – 0 is off

(or no charge) and 1 is on (or charged).


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XPHow data gets into chips

A Byte of data


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XPComputer code for different types of data

• There are many methods for coding computer data. For instance:– Text data might be stored in ASCII

– Bitmap images stored using binary color code

– Numbers stored in binary

– Sound stored with binary codes to represent wave samples


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• All of the computer codes, however, share characteristics:– They are digital, a finite set of numbers

– They are all binary, stored using only 0s and 1s

– They re all fixed length, using the same number of bits to represent each character.


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0 00110000 C 01000011 V 01010110 I 011010011 00110001 D 01000100 W 01010111 j 011010102 00110010 E 01000101 X 01011000 k 011010113 00110011 F 01000110 Y 01011001 l 011011004 00110100 G 01000111 Z 01011010 m 011011015 00110101 H 01001000 [ 01011011 n 011011106 00110110 I 01001001 \ 01011100 o 011011117 00110111 J 01001010 ] 01011101 p 011100008 00111000 K 01001011 ^ 01011110 q 011100019 00111001 L 01001100 - 01011111 r 01110010: 00111010 M 01001101 ' 01100000 s 01110011; 00111011 N 01001110 a 01100001 t 01110100< 00111100 O 01001111 b 01100010 u 01110101 = 00111101 P 01010000 c 01100011 v 01110110> 00111110 Q 01010001 d 01100100 w 01110111? 00111111 R 01010010 e 01100101 x 01111000@ 01000000 S 01010011 f 01100110 y 01111001A 01000001 T 01010100 g 01100111 z 01111010B 01000010 U 01010101 h 01101000

A table of ASCII codes


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XPTying software into chips, codes and circuits

• All software consists of a series of instructions written in a programming language such as Visual Basic or Java.

• Once written, these program language instructions are converted to machine language (binary codes) so that they can be read by the computer.

• The conversion process is called compiling the program.


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XPTying software into chips, codes and circuits

A computer program and it’s machine language


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XPHardware – Microprocessors

• A PC contains a microprocessor (or brain) that controls the types of programs it can run and how fast it can process.

• There are two main types of microprocessors today:– X86 processors found in PCs that run Windows (called

IBM compatibles)

– PowerPC processors found in Apple Macintosh computers


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• The PowerPC is a reduced instruction set computer (RISC) chip.

• The X86 is a complex instruction set computer (CISC) chip.

• The issue of which of these chips is more efficient is a matter of controversy.


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A Pentium 4 chip beside an Athlon chip


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• Processor speed called clock speed contributes to overall system performance.

• Clock speed is measured in megahertz (MHz) or millions of cycles per second.

• The faster the clock speed, the more instructions a processor can process in a second.

• Some processors can process multiple instructions per clock cycle. These are referred to as superscalar.


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• Cache memory, it’s size and location is also a factor of processor speed.

• Level 1 cache is on the microprocessor chip.• Level 2 is on a separate chip, but closer than

RAM.• Some processors have extended instruction sets

that speed up their processing time.


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• MMX (multimedia extensions) accelerate the processing of 2-D graphics, video and sound.

• SSE ( streaming SIMD extensions) accelerate video, speech, image and photo processing.

• 3DNow! extensions speed up processing 3-D graphics.


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• Benchmark tests rate computer performance by measuring the time it takes to do standard instruction sets. There are three categories of benchmarks:– Multimedia benchmarks measure performance with

multimedia data.

– Integer benchmarks measure number processing.

– Floating point benchmarks measure performance with floating point numbers used in special situations like CAD.


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Results of a processor benchmark


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XPFinding the technical specifications for your PC

Using Windows to view technical specifications


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XPWhat do you think?

Who invented the first electronic digital computer?

1. Does it appear to you that the judge made the right decision, despite the fact that Atanasoff never filed for a patent?

2. Do you think that Zuse, instead of Atanasoff, should be declared the inventor of the first electronic digital computer?

3. Do you think that the computer industry would be different today if Sperry Rand had won its [patent case?


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XPChapter Summary

• You should now be able to:– Understand the basic workings of your computer

– Know what RAM and processing circuitry looks like

– Understand binary coding of data

– Understand how different types of data is coded

– How software and hardware tie together

– Find the technical specifications for your PC

– About the basic types of Microprocessors

xp practical pc, 3e chapter 16 1 looking “under the hood”

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