1. Computer Architecture
Section A
Digital Electronics
CHAPTER 5
Computer Architecture
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2. Section A Digital Electronics 5 Section PREVIEW You will be able to:
Chapter 5
Section PREVIEW
Section D
Section A
You will be able to:
Identify the components that are on the main circuit board - the motherboard -of a microcomputer
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3. Section A Digital Electronics 5
Chapter 5
Section A
Computer architecture refers to the design and construction of a computer system.
based on power source
based on how computer physically represents, processes, moves, and stores data
Modern computers are powered by electricity and use electric signals and circuits to represent, process, and move data.
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4. 5 Inside the System Unit What does the inside of a computer look like?
Chapter 5
Section A
CD-ROM
drive
Power
Supply
Floppy
disk drive
Hard
disk drive
Circuit
boards
Wires and
ribbon cables
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5. Integrated Circuits
Why isn’t the system unit filled with a lot of wires?
Chapter 5
Section A
Most electronic components inside a computer are integrated circuits - thin slices of silicon crystal packed with microscopic circuit elements
wires
transistors
capacitors
resistors
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6. Integrated Circuits
Why isn’t the system unit filled with a lot of wires?
Chapter 5
Section A
Inside a computer, you are likely to find several kinds of chip packages, including DIP, DIMM, PGA, and SEC.
Example of
DIPs
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7. 5 The Motherboard How do the chips fit together to make a computer?
Chapter 5
Section A
Chips are housed on a circuit board called a motherboard.
contains processor chip
computer memory chips
chips that handle basic input/output
contains expansion slots for peripheral devices
Some chips are soldered (permanent), some are removable (can be upgraded)
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8. 5 The Motherboard How do the chips fit together to make a computer?
Chapter 5
Section A
Support
chips
Random
access
memory
chips
ROM
chips
Microprocessor
chip
Circuitry
Expansion
cards
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9. 5 Digital Data Representation
If a computer is just a bunch of electrical circuits, how can it manipulate data?
Chapter 5
Section A
Most of today’s computers are digital devices
work with distinct numbers or digits
An analog device operates on continuously varying data
The pulse of
electricity down
a circuit could
represent 1 bit
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10. 5 Data Representation Codes
Do all digital computers use the same code to represent data?
Chapter 5
Section A
Computers represent data using the binary number system and several other codes designed for computer data.
Binary number system (base 2)
has only two digits: 1 and 0
converted into “ons” and “offs”
number 2 cannot be used
Numeric data - numbers that represent quantities
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11. 5 Data Representation Codes
Do all digital computers use the same code to represent data?
Chapter 5
Section A
Character data is composed of letters, symbols, and numerals that will not be used in arithmetic operations.
name, address, etc.
Digital computers represent character data using ASCII (American Standard Code for Information Interchange) and EBCDIC.
IBM-brand mainframe computers often use EBCDIC (Extended Binary-Coded Decimal Interchange Code).
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12. 5 Data Representation Codes
Do all digital computers use the same code to represent data?
Chapter 5
Section A
An example
of data codes
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13. 5 Data Transport What happens to the data in a computer?
Chapter 5
Section A
Data travels from one location to another on an electronic circuit called a data bus.
Data bus - series of circuits that connect various electrical components on the motherboard
contains data lines and address lines
Data lines - carry the signals that represent data
Address lines - carry signals that specify where computer can find data to process
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14. Computer Architecture
Section B
Memory
CHAPTER 5
Computer Architecture
Page 215

15. Section B Memory 5 Section PREVIEW You will be able to:
Chapter 5
Section PREVIEW
Section D
Section B
You will be able to:
Explain how RAM, virtual memory, ROM, and CMOS differ
Page 215

16. Section B
Memory
Chapter 5
Section B
There are four major types of memory, each characterized by the data it contains and the technology it uses to hold the data.
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17. 5 Random Access Memory How does RAM work?
Chapter 5
Section B
RAM (random access memory) - an area of the computer that holds data before and after it is processed
as you type, characters are held in RAM
Capacitors are microscopic electronic parts that hold the electronic signals for the code that represents data.
charged capacitor = ON
discharged capacitor = OFF
each bank of capacitors holds eight bits
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18. 5 Random Access Memory How does RAM work? Each RAM location
Chapter 5
Section B
Each RAM location
has an address
and holds one
byte of data
by using eight
capacitors to
represent the
eight bits in a byte.
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19. 5 Random Access Memory How does RAM work?
Chapter 5
A RAM address on each bank helps the computer locate the data in that bank.
RAM is a reusable computing source.
RAM is volatile: requires power to hold data.
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20. 5 RAM Functions Why is RAM so important? RAM
Chapter 5
Section B
Section B
RAM
holds data waiting to be processed
holds instructions that will process the data
holds processed data before it is stored elsewhere
holds operating system instructions
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21. 5 RAM Capacity, Speed, and Configuration
How much RAM does my computer need?
Chapter 5
Section B
Section B
Storage is measured in RAM
Today’s computers have between 64 and 256 megabytes of RAM
Amount of RAM depends on software you use
You can purchase additional RAM
Today’s RAM has access speeds as fast as 8 nanoseconds, one billionth of a second
RAM is configured as a series of DIPS soldered onto a circuit board called a DIMM
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22. 5 Virtual Memory What if I run out of RAM?
Chapter 5
Section B
Section B
A computer can use disk storage to simulate RAM. This is called virtual memory.
not as fast as RAM
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23. 5 Read-Only Memory If a computer has RAM, why does it need ROM?
Chapter 5
Section B
ROM (read-only memory) is one or more chips containing instructions that help a computer prepare to process tasks.
Since RAM is empty when a computer is turned on, ROM BIOS is used.
ROM BIOS (basic input/output system) is a set of instructions that tells computer how to access the disk drives and peripheral devices.
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24. CMOS Memory
If the boot instructions are permanent, can I change any hardware on my system?
Chapter 5
Section B
A computer needs a semi-permanent way of keeping boot data, such as the number of hard disk sectors and cylinders.
CMOS memory - holds data but requires very little power to retain its contents.
can run by a battery on the motherboard
housed within the same chip carrier as ROM BIOS
Some computers have plug and play feature for updating CMOS.
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25. Computer Architecture
Section C
Central Processing Unit
CHAPTER 5
Computer Architecture
Page 220

26. Central Processing Unit 5
Section C
Central Processing Unit
Chapter 5
Section PREVIEW
Section D
Section C
You will be able to:
Explain how the CPU performs instructions contained in a computer program
List the factors that affect CPU performance
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27. Central Processing Unit 5
Section C
Central Processing Unit
Chapter 5
Section C
The central processing unit is the circuitry in a computer that executes instructions to process data.
Page 220

28. 5 Central Processing Unit Architecture What does the CPU look like?
Chapter 5
Section C
In 1945, the size of a CPU was measured in feet; today, they are measured in mils (0.001 inch)
The ENIAC
built in 1944
was two feet
wide and eight
feet high.
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29. 5 Central Processing Unit Architecture What does the CPU look like?
Chapter 5
Section C
In a microcomputer, the CPU is a single integrated circuit called a microprocessor.
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30. 5 Central Processing Unit Architecture What does the CPU look like?
Chapter 5
Section C
The CPU has two parts
ALU (arithmetic logic unit)
performs arithmetic operations
performs logical operations
uses registers to hold data being processed
The result of an operation is place in the accumulator.
From accumulator data, it can be sent to RAM or used for further processing.
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31. 5 Central Processing Unit Architecture What does the CPU look like?
Chapter 5
Section C
The CPU’s control unit directs and coordinates processing.
The control unit’s instruction pointer tracks sequence of instructions.
places in instruction register
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32. 5 Central Processing Unit Architecture What does the CPU look like?
Chapter 5
Section C
play animation f0518
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33. Instructions
What specifies the steps that the CPU must perform to accomplish a task?
Chapter 5
Section C
An instruction (a series of simple steps) tells the computer to perform arithmetic, logical or control operations.
Op code - part of the instruction which stands for operation code is a command word such as:
add
compare
jump
Operand - specify data or address of data for operation
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34. Instructions
What specifies the steps that the CPU must perform to accomplish a task?
Chapter 5
Section C
JMP M1
In this example JMP means jump and M1 is the RAM address of the instruction the computer is supposed to go to.
An instruction set is the list of instructions a CPU is able to execute.
op code
operand
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35. 5 Instruction Cycle How does a computer process instructions?
Chapter 5
Section C
The process in which a computer executes a single instruction is called the instruction cycle.
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36. 5 CPU Performance Factors
How does the architecture of a computer contribute to its performance?
Chapter 5
Section C
CPU speed is influenced by several factors:
clock rate
word size
cache
instruction set size
A computer with a high-performance processor may have:
slow hard disk
small amount of RAM
no disk cache
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37. Clock Rate
What does the date and time have to do with CPU performance?
Chapter 5
Section C
A computer’s system clock is not the same as a “real-time” clock.
System clock - emits pulses to establish the timing for all system operations
sets speed for data transport and instruction execution
The time it takes to complete an instruction cycle is measured in megahertz.
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38. 5 Word Size Which is faster, an 8-bit processor or a 64-bit processor?
Chapter 5
Section C
Section C
Word size - the number of bits that the CPU can manipulate at once.
based on size of registers in CPU
based on number of data lines in the bus
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39. 5 Cache Is there a process that speeds access to data from RAM?
Chapter 5
Section C
Cache - special high-speed memory that gives CPU more rapid access to data
The cache ensures that data is immediately available whenever the CPU requests it.
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40. 5 Instruction Set Complexity
What’s the difference between CISC and RISC?
Chapter 5
Section C
Computers based on a CPU with a complex instruction set known as CISC (complex instruction set computer) machine.
A RISC (reduced instruction set computer) has limited set of instructions that it can perform quickly.
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41. 5 Pipelining and Parallel Processing
Can a CPU increase its performance by executing more than one instruction at a time?
Chapter 5
Section C
Computers with a single processor execute instructions serially (one at a time).
Pipelining - technology in which processor can begin executing next instruction before it completes previous instruction.
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42. 5 Pipelining and Parallel Processing
Can a CPU increase its performance by executing more than one instruction at a time?
Chapter 5
Section C
A computer with more than one processor can execute multiple instructions simultaneously, referred to as parallel processing.
Computers that use parallel processing are called parallel computers.
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43. Computer Architecture
Section D
Input/Output
CHAPTER 5
Computer Architecture
Page 229

44. Section D Input/Output 5 Section PREVIEW You will be able to:
Chapter 5
Section PREVIEW
Section D
Section D
You will be able to:
Describe how the data bus and the expansion bus work
List the components necessary to connect a peripheral device to a computer and describe each component’s role
Page 229

45. Section D Input/Output 5
Chapter 5
Section D
You will most likely want to add equipment to your computer to expand its capabilities
I/O (computer jargon for input/output) refers to collecting data and transporting results.
Expansion bus - the segment of the data bus that transports data between RAM and peripheral devices
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46. Section D Input/Output 5 3. Expansion slot extends the expansion
Chapter 5
3. Expansion slot
extends the expansion
bus to an expansion
card
Section D
4. Expansion card
contains a port
1. Data originates
in RAM
2. Expansion
bus transports data
along circuits on
the motherboard.
5. Data cable plugs
into the port, then
leads to a peripheral
device.
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47. 5 Expansion Slots and Cards How do I use expansion slots?
Chapter 5
Section D
Expansion slot - long, narrow socket on the motherboard into which you can plug an expansion card
Expansion card - small circuit board that provides computer with ability to control storage, input or output device
Most microcomputers have expansion slots.
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48. 5 Expansion Slots and Cards How do I use expansion slots?
Chapter 5
Section D
Today’s microcomputers come with
graphics card (for connecting monitor)
modem (for transmitting data over phone or cable lines)
sound card (for connecting speakers)
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49. 5 Expansion Slots and Cards How do I use expansion slots?
Chapter 5
Section D
The microcomputer motherboard typically has:
ISA - older technology, modems and slow devices
PCI - for graphics, sound, video, modem or network cards
AGP - for graphics cards
Expansion cards are built for only one type of slot.
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50. 5 Expansion Ports and Cables
How do I connect a peripheral device to an expansion card?
Chapter 5
Section D
To connect a peripheral device to an expansion card, you plug a cable from the device into the expansion port.
Expansion port - any connector that passes data in and out of a computer or peripheral device.
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51. 5 Expansion Ports and Cables
How do I connect a peripheral device to an expansion card?
Chapter 5
Section D
Page 233

52. Computer Architecture
User Focus
Troubleshooting Boot Process
CHAPTER 5
Computer Architecture
Page 234

53. 5 User Focus Troubleshooting Boot Process Section PREVIEW
Chapter 5
Section PREVIEW
Section D
You will be able to:
Troubleshoot the boot process of your computer system
Page 234

54. 5 User Focus Troubleshooting Boot Process
Chapter 5
User Focus
Boot process - sequence of events that occurs between the time you turn on a computer and the time it is ready for you to issue commands
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55. An Overview
If the computer memory is blank when I turn it on, how does it know how to start up?
Chapter 5
User Focus
The boot process follows these steps:
1. Power up
2. Start boot program
3. Power-on self-test
4. Load operating system
5. Check configuration and customization
6. Ready for commands and data
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56. 5 Power Up What if I turn the computer on but nothing happens?
Chapter 5
User Focus
If nothing happens, the system is not getting power.
When you turn on
a computer, you
should see the power light
and hear the fan.
Fan
Power light
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57. 5 Start Boot Program What happens if the ROM is malfunctioning?
Chapter 5
User Focus
If the ROM chips, RAM modules, or microprocessor are malfunctioning, the microprocessor will be unable to run the boot program.
The computer stops or “hangs”.
light is on
fan is on
no message on screen
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58. Power-On Self-Test
Can the computer check to determine if all its components are functioning correctly?
Chapter 5
User Focus
The Power-On Self-Test (POST) diagnoses problems in the computer.
POST
checks graphics card
tests RAM
checks keyboard
performs drive test
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59. 5 Check Configuration and Customization
Does the computer get all of its configuration data from CMOS?
Chapter 5
User Focus
The computer checks CMOS; however, more configuration data is needed.
The computer searches root directory for configuration settings.
stored as Config.sys or Windows Registry
Windows Registry - contains settings that a computer needs to correctly use its hardware devices and software
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60. 5 Ready for Commands and Data
How do I know when the computer has finished booting?
Chapter 5
User Focus
The boot process is complete when the computer is ready to accept your commands.
You can enter commands and
launch programs.
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61. 5 Ready for Commands and Data
How do I know when the computer has finished booting?
Chapter 5
User Focus
If Windows cannot complete the boot process, you’re likely to see an option to choose Safe Mode.
Safe Mode - limited version of Windows that allows you to use mouse, monitor, and keyboards
no peripherals.
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