Transcript Discovering Computers 2012

Discovering
Computers 2012
Your Interactive Guide
to the Digital World
Objectives Overview
Differentiate among various
styles of system units on
desktop computers,
notebook computers, and
mobile devices
Identify chips, adapter
cards, and other
components of a
motherboard
Identify characteristics of
various personal computer
processors on the market
today, and describe the
ways processors are cooled
See Page 209
for Detailed Objectives
Describe the control unit
and arithmetic logic unit
components of a processor,
and explain the four steps in
a machine cycle
Define a bit and describe
how a series of bits
represents data
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The System Unit
• The system unit is a case that contains electronic
components of the computer used to process data.
• Made of metal or plastic to protects the
internal components from damage.
• All computers have a system unit. It is available
in variety of shapes & sizes.
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Figure 4-1
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The System Unit
• The inside of the system unit on a desktop
personal computer includes:
Drive bay(s)
Power supply
Sound card
Video card
Processor
Memory
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Figure 4-2
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System unit components
 Processor interprets & carries out the basic instructions that operate a
computer.
 Memory holds data waiting to be processed & instruction waiting to be
executed.
 Processor & Memory are connected to a circuit board called the
motherboard.
 Adapter cards are circuit boards that provide connections and
functions not built into the motherboard.
 Devices outside the system unit often attach to the ports.
 A drive bay holds one or more disk drive.
 The Power supply provide the computer with the electricity.
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Motherboard
• The motherboard is the
main circuit board of the
system unit.
• Contains expansion slots,
processor chips, and
memory slots
• Sometimes called a
system board
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Motherboard
•
Most computers use integrated circuits also called chips ,
for their CPU and main memory.
•
Memory chips are installed on memory module( card)
that fit in a slot on the mother board.
• What is a chip?
•
Small piece of semi-conducting material on which
integrated circuits (IC) are etched.
•
IC contain many microscopic pathways capable of
carrying electrical current.
• Each IC can contain millions of elements such as resistors,
capacitors, transistors.
Next
Processor
• The processor, also called the central processing
unit (CPU), interprets and carries out the basic
instructions that operate a computer
– Contain a control unit and an arithmetic logic unit
(ALU) that work together to perform processing
operations
Multi-core
processor
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Dual-core
processor
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Quad-core
processor
9
• A dual-core processor is a single chip that contains
two
separate processors
• A multi-core processor is a chip with two or more
separate processors
• Each processor on a dual-core/multi-core chip
generally
runs at a slower clock speed, but increase overall
performance
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Processor
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Figure 4-4
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CPU operations
The operations typically performed by a CPU are:
1.
CPUs control the reading of programs and input files.
1. Its activates input unit to read program and data.
2. Controls the transmission of program & data files from disk to main memory.
2. CPUs process data according to instructions in a program.
1. Data can be processed arithmetically- number can be added, subtracted,
multiplied and divided.
2. Logical tests can be performed on data. E.g., comparison.
3. Data can be transmitted or copied from one area of primary storage to another.
3. CPUs control the creation of output.
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Processor
• The control unit is the component of the processor
that directs and coordinates most of the operations
in the computer.
– Handles the transmission of data into and out of the CPU
and supervises its overall operations.
– Its interprets each instruction issued by a program & then
initiates the appropriate action to carry out the
instruction.
• The arithmetic logic unit (ALU) performs arithmetic,
comparison, and other operations.
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Processor
• For every instruction, a processor repeats a set of
four basic operations, which comprise a machine
cycle
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Figure 4-5
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For every instruction, a processor repeats a set of
four basic operations:
1. Fetching process of obtaining a program instruction or data item from
memory.
2. Decoding process of translating the instruction into signals the
computer can execute.
3. Executing process of carrying out the commands.
4. Storing, if necessary. Means writing the result to memory.
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Processor
The processor contains registers, that
temporarily hold data and instructions
The system clock controls the timing
of all computer operations
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Processor
Registers
• The registers are special storage areas in the CPU.
• Their function is to hold instructions, data values, memory
addresses of both the instructions and data.
• There are 4 basic types of it: CU, ALU
• Instruction register hold instruction
• Address register hold address of( data , next instruction ).
• Storage register store data retrieved from main memory prior to
processing.
• Accumulator store the results of arithmetic & logic operations
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Processor
System clock
• It generates regular electronic pulses , or ticks,
that control the timing of all computer operations
( i.e. set operating pace of components of system
unit)
• Pace of system clock is clock speed. Most clock speeds
are in the gigahertz (GHz) range (1 GHz = one
billion ticks of system clock per second).

Processing actions occur at each “tick” of the electronic clock.


The Speed of the clock determines the speed at which the CPU can process data.
The faster the clock speed, the more instruction the processor can execute per second
(hertz).
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Processor
• Most current personal
computers support
pipelining
– Processor begins
fetching a second
instruction before it
completes the machine
cycle for the first
instruction
Pages 215 – 216
Figure 4-6
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Processor
• Parallel processing uses multiple processors
simultaneously to execute a single program or task
– Massively parallel processing involves hundreds or thousands of
processors
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Figure 4-11
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Processor
• The leading manufacturers of
personal computer processor
chips are Intel and AMD
• They often identify their processor chip
by a model name or model number.
• Other leading processor chip
manufacturers
 Transmeta
 IBM
 Motorola
– IBM processor had a different design
from the Intel-style processor.
Pages 216 – 217
Figure 4-7
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Processor
• Determine
how you
plan to use a
new
computer
before
selecting a
processor
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Figure 4-8
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Processor
• A processor chip
generates heat that
could cause the chip to
burn up
• Require additional
cooling
– Heat sinks
– Liquid cooling
technology
Pages 219 - 220
Figures 4-9 – 4-10
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Data Representation
Analog signals are continuous and vary in strength and quality
Digital signals are in one of two states: on or off
• Most computers are digital recognize only two discrete states: on or off.
• Use a binary system to recognize two states
• Use number system with two unique digits: 0 and 1, called bits (short for
binary digits)
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Data Representation
A computer circuit represents
the 0 or the 1 electronically by
the presence or absence of an
electrical charge
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Figures 4-12 – 4-13
Eight bits grouped together as a
unit are called a byte. A byte
represents a single character in
the computer ( numbers, upper
or lower case letters, or
punctuation marks)
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Data Representation
• The different combinations of 0s and 1s are defined by patterns
called a coding schema.
• There are two coding schemas used to represent data

ASCII—American Standard Code for Information Interchange
[Personal Computers – PCS]

EBCDIC—Extended Binary Coded Decimal Interchange Code
[Mainframes, Mini-computers]
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Figure 4-14
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Data Representation
• ASCII is the most widely used coding scheme to
represent data
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Figure 4-14
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Data Representation
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Figure 4-15
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