1. Practical PC, 7th Edition Chapter 17: Looking Under the Hood

2. Looking Under the Hood FAQ’s Technology: Microprocessors
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?
Technology: Microprocessors
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3. 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
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4. How does a computer work?
The computer puts data into RAM (Random Access Memory), a temporary holding area for data
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”
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5. How does a computer work?
Data is processed in the microprocessor
Control Unit
Gets instructions from computer software
Registers
Hold data that is being processed
ALU (Arithmetic logic unit)
Performs arithmetic and comparison operations
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6. How does a computer work?
Practical PC, 7th Edition

7. 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 (read-only memory) chips: hold the instructions for PC to boot up
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8. What do RAM and processing circuitry look like?
Chip is housed in small, black, rectangular chip carrier which is connected to a circuit board
Circuit board contains electrical pathways that allow data to travel between chips
In a typical PC, a system board houses the microprocessor chip, ROM chips, and support chips
System board is referred to as a motherboard or mainboard
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9. What do RAM and processing circuitry look like?
Practical PC, 7th Edition

10. How does data get into chips?
Data is converted into code and then into electronic signals that travel through circuits on chips and circuit boards
Computer codes are based on ones and zeros
Each 1 or 0 is a bit (short for binary digit)
Eight bits form a byte, which typically form one character
Data is coded and either stored or transmitted electronically
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11. How does data get into chips?
Practical PC, 7th Edition

12. How does data get into chips?
As data is gathered, processed, stored, and transmitted, it is constantly converted from one type of signal to another
Special controller chips convert the data into different styles of signals
These chips are found on system boards, graphics cards, sound cards, and modems
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13. Does a computer use the same code for all types of data?
Computers use different codes for different types of data but all have common characteristics
Digital
A digit is a single character in a numbering system
Data is converted into a finite set of numbers
Binary
This system uses only two digits, 0 and 1
0 is “off” and 1 is “on”
Fixed Length
The same number of bits is used to represent each data item
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14. Does a computer use the same code for all types of data?
Types of Codes
Text data are stored using ASCII, Extended ASCII, and Unicode
Numbers for calculations use the binary number system
Numbers not used for calculations use ASCII, Extended ASCII, or Unicode
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15. Does a computer use the same code for all types of data?
Practical PC, 7th Edition

16. Does a computer use the same code for all types of data?
Bitmap images
Binary color code for each pixel in the image
Simplest code uses three bytes of data. Each byte defines how much red, blue, and green are in the color
Figure 17-5
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17. Does a computer use the same code for all types of data?
Digital audio
Binary number represents height of each wave sample
Each sample is stored as an 8-bit number for radio-quality recordings
High-fidelity recordings are stored as a 16-bit number
Figure 17-6
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18. Technology: Microprocessors
A microprocessor is an integrated circuit that is the main processing device in a PC
Most computers contain x86 microprocessors
Ancestry goes back to the first generation of PCs
New x86 processors are faster and more capable but can still run software designed for the first generation of x86 processors
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19. Technology: Microprocessors
Manufacturers
Intel
Original chipmaker and still the largest
Current chip is the Intel Core i7
AMD
Current offering includes the A series
Figure 17-8
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20. Technology: Microprocessors
Clock speed
Contributes to overall system performance
Measured in gigahertz (GHz)
One GHz is 1 billion cycles per second
The faster the clock speed, the more instructions the processor can carry out in each second
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21. Technology: Microprocessors
Factors that affect the microprocessor speed:
Instructions per clock cycle
Processors that execute multiple instructions per clock cycle are referred to as superscalar
CPU Cache
Data-holding circuitry that can be accessed faster than RAM
Measured in kilobytes (KB)
Most of today’s microprocessors have multi-level caches--L1, L2, or L3
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22. Technology: Microprocessors
Accelerated front side bus
Circuitry that moves data to the microprocessor
Moves data quickly--HyperTransport and Quickpath
Allows processor to work at full capacity
Extended instruction set
Speeds up video or photo processing
Multi-core architecture
A multi-core processor is a single microprocessor chip whose circuitry allows more than one instruction to be processed at a time
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23. Technology: Microprocessors
Word size
Refers to the number of bits that a microprocessor can manipulate at one time
Based on size of registers: 64-bit vs 32-bit
Most personal computers contain 64-bit processors
32-bit processors are used primarily for tablets
Larger word size means more data can be processed during each processor cycle
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24. Technology: Microprocessors
Benchmark test
A set of standard processing tasks that measure the performance of computer hardware and software
Microprocessor benchmark tests measure how fast processors perform a set of tasks
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25. Technology: Microprocessors
Types of benchmark tests
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
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26. Technology: Microprocessors
Windows Experience Index
Practical PC, 7th Edition