1. Chapter 3: Computer Hardware Components: CPU, Memory, and I/O
Berlin Chen 2003
Textbooks: 1. Kurt F. Lauckner and Mildred D. Lintner, "The Computer Continuum,"
Prentice Hall, Second Edition, 2001.
The Computer Continuum

2. What is the typical configuration of a computer sold today?
Chapter 3
What is the typical configuration of a computer sold today?
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3. Chapter 3
Outline
How did the computer become known as the stored-program computer?
Do they all have the same characteristics?
Memory on chips and memory on magnetic media, how do they differ?
What do you look for when comparing memory devices?
How is information moved around within the computer?
How can you help your computer run better?
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4. Basic Concepts of Computer Hardware
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Basic Concepts of Computer Hardware
Primary Memory
Input
Units
Output
Units
CPU
(Central Processing Unit)
This model of the typical digital computer is often called the von Neumann computer
Programs and data are stored in the same memory: primary memory
The computer can only perform one instruction at a time
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5. Basic Concepts of Computer Hardware
Chapter 3
Basic Concepts of Computer Hardware
Input/Output (I/O): Refers to the process of getting information into and out of the computer
Input: Those parts of the computer receiving information to programs
Output: Those parts of the computer that provide results of computation to the person using the computer
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6. Sources of Data for the Computer
Chapter 3
Sources of Data for the Computer
Two types of data stored within a computer
Original data or information: Data being introduced to a computing system for the first time
Computers can deal directly with printed text, pictures, sound, and other common types of information
Previously stored data or information: Data that has already been processed by a computer and is being stored for later use
These are forms of binary data useful only to the computer
Examples: Floppy disks, DVD disks, and music CDs
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7. Input Devices Two categories of input hardware:
Chapter 3
Input Devices
Two categories of input hardware:
Those that deal with original data
Those that handle previously stored data
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8. Input Devices Input hardware: Those that deal with original data.
Chapter 3
Input Devices
Input hardware: Those that deal with original data.
Keyboard
Mouse
Voice recognition hardware
Scanner
Digital camera
Digitizing: The process of taking a visual image, or audio recording and converting it to a binary form for the computer
Used as data for programs to display, play or manipulate the digitized data
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9. Input Devices Connecting Hardware to the computer:
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Input Devices
Connecting Hardware to the computer:
Hardware needs access through some general input/output connection.
Port: The pathway for data to go into and out of the computer from external devices such as keyboards
There are many standard ports as well as custom electronic ports designed for special purposes
Ports follow standards that define their use
SCSI, USB: Multiple peripheral devices (chain)
RS-232, IDE: Individual peripheral devices
Peripheral device: A piece of hardware like a printer or disk drive, that is outside the main computer
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10. Input Devices Connecting Hardware to the computer: (continued)
Chapter 3
Input Devices
Connecting Hardware to the computer: (continued)
Hardware needs software on the computer that can service the device.
Device driver: Software addition to the operating system that will allow the computer to communicate with a particular device.
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11. Chapter 3
Input Devices
Common Basic Technologies for Storing Binary Information:
Electronic
Magnetic
Optical
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12. Input Devices Electronic Circuits
Chapter 3
Input Devices
Electronic Circuits
Most expensive of the three forms for storing binary information.
A flip-flop circuit has either one electronic status or the other. It is said to flip-flop from one to the other.
Electronic circuits come in two forms:
Permanent
Non-permanent
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13. Input Devices Magnetic Technology
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Input Devices
Magnetic Technology
Two parts to most of the magnetic forms of information storage:
The medium that stores the magnetic information.
Example: Floppy disk. Tiny spots on the disk are magnetized to represent 0s and 1s.
The device that can “read” that information from the medium.
The drive spins the disk.
It has a magnetic sensing arm that moves over the disk.
Performs nondestructive reading.
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14. Chapter 3
Input Devices
Optical
Uses lasers to “read” the binary information from the medium, usually a disc.
Millions of tiny holes are “burned” into the surface of the disc.
The holes are interpreted as 1s. The absence of holes are interpreted as 0s.
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15. Input Devices Secondary Memory Input Devices
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Input Devices
Secondary Memory Input Devices
These input devices are used by a computer to store information and then to retrieve that information as needed.
External to the computer.
Commonly consists of floppy disks, hard disk drives, or CD-ROMs.
Secondary memory uses binary.
The usual measurement is the byte.
A byte consists of 8 binary digits (bits). The byte is a standard unit.
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16. Chapter 3
Input Devices
The four most important characteristics of storage devices:
Speed and access time
Cost / Removable versus non-removable
Capacity
Type of access
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17. Chapter 3
Input Devices
Speed (Access time) - How fast information can be taken from or stored onto the computer memory device’s medium
Electronic circuits: Fastest to access
40 billionths of a second
Floppy disks: Very slow in comparison
Takes up to 1/2 second to reach full speed before access is even possible
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18. Input Devices Cost Megabyte: A Million bytes Gigabyte: A billion bytes
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Input Devices
Cost
Megabyte: A Million bytes
Gigabyte: A billion bytes
Two parts to a removable secondary storage device
The cost of the medium (Cheaper if bought in quantity)
The cost of the drive
Examples: Cost for drive Cost for medium
Floppy drive (1.4MB)
Zip 100 (100 MB)
CD-WR (650 MB) and up 1.00
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19. Chapter 3
Input Devices
Capacity - The amount of information that can be stored on the medium.
Unit Description Approximate Size
1 bit 1 binary digit
1 nibble 4 bits
1 byte 8 bits 1 character
1 kilobyte 1,024 bytes 1/2 page, double spaced
1 megabyte 1,048,576 bytes 500,000 pages
1 million bytes
1 gigabyte 1,073,741,824 bytes 5 million pages
1 billion bytes
1 terabyte 1 trillion bytes 5 billion pages
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20. Input Devices Type of Access
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Input Devices
Type of Access
Sequential - Obtained by proceeding through the storage medium from the beginning until the designated area is reached (as in magnetic tape)
Random Access - Direct access (as in floppy and hard disks)
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21. Chapter 3
Primary Memory
Primary storage or memory: Is where the data and program that are currently in operation or being accessed are stored during use
Consists of electronic circuits: Extremely fast and expensive
Two types
RAM (non-permanent)
Programs and data can be stored here for the computer’s use
Volatile: All information will be lost once the computer shuts down
ROM (permanent)
Contents do not change
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22. The Central Processing Unit
Chapter 3
The Central Processing Unit
The Central Processing Unit ( CPU)
Often referred to as the “brain” of the computer
Responsible for controlling all activities of the computer system
The three major components of the CPU are:
1. Arithmetic Unit (Computations performed)
Accumulator (Results of computations kept here)
2. Control Unit (Has two locations where numbers are kept)
Instruction Register (Instruction placed here for analysis)
Program Counter (Which instruction will be performed next?)
3. Instruction Decoding Unit (Decodes the instruction)
Motherboard: The place where most of the electronics including the CPU are mounted
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23. Chapter 3
Output Devices
Output units store and display information (calculated results and other messages) for us to see and use.
Floppy disk drives and Hard disk drives.
Display monitors: Hi-resolution monitors come in two types:
Cathode ray tube (CRT) - Streams of electrons make phosphors glow on a large vacuum tube
Liquid crystal display (LCD) - A flat panel display that uses crystals to let varying amounts of different colored light to pass through it
Developed primarily for portable computers
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24. Output Devices Audio Output Devices
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Output Devices
Audio Output Devices
Windows machines need special audio card for audio output
Macintosh has audio playback built in
Audio output is useful for
Music
CD player is a computer
Most personal computers have CD players that can access both music CDs and CD-ROMs
Voice synthesis (becoming more human sounding.)
Multimedia
Specialized tasks (i.e.: elevator’s floor announcements)
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25. Output Devices Optical Disks: CD-ROM and DVD
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Output Devices
Optical Disks: CD-ROM and DVD
CD-ROM (Compact Disk - Read Only Memory)
By its definition, CD-ROM is Read Only
Special CD drives “burn” information into blank CDs
Burn: A laser is used to “burn” craters into the surface to represent a binary 1
Two main types of CDs
CD-R (Compact Disk - Recordable)
CD-WR (Compact Disk – Re-Writable)
It takes longer to write to a CD-R than a hard drive
Special software is needed to record
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26. Output Devices DVD (Digital Versatile Disk)
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Output Devices
DVD (Digital Versatile Disk)
Allows up to 17 gigabytes of storage (from 4.7 GB to 17 GB).
Compatible with older CD-ROM technology.
The four versions of the DVD:
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27. Chapter 3
Output Devices
Storage Requirements: How much storage capacity is needed for…
One keystroke on a keyboard. 1 byte (8 bits)
One page single-spaced document. 4.0 K
Nineteen pages formatted text. 75 K
One second of high-fidelity sound K
Complete word processing program. 8.4 MG
Storage Capacity: How much data can be stored on…
One inch of 1/2 in. wide magnetic tape. 4 K
One 3 1/2” floppy disk, high density. 1.4 MG
One Compact Disk. 650 MG
One DVD. up to 17 GB
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28. Moving Information Within the Computer
Chapter 3
Moving Information Within the Computer
How do binary numerals move into, out of, and within the computer?
Information is moved about in bytes, or multiple bytes called words
Words are the fundamental units of information
The number of bits per word may vary per computer
A word length for most large IBM computers is 32 bits
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29. Moving Information Within the Computer
Chapter 3
Moving Information Within the Computer
Bits that compose a word are passed in parallel from place to place.
Ribbon cables:
Consist of several wires, molded together
One wire for each bit of the word or byte
Additional wires coordinate the activity of moving information
Each wire sends information in the form of a voltage pulse
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30. Moving Information Within the Computer
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Moving Information Within the Computer
Example of sending the word WOW over the ribbon cable
Voltage pulses corresponding to the ASCII codes would pass through the cable.
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31. Packaging the Computer
Chapter 3
Packaging the Computer
The many physical forms of the general purpose computer:
All follow general organization:
Primary memory
Input units
Output units
Central Processing Unit
Grouped according to speed, cost, size, and complexity.
Fast Expensive Complex Large
Super Computers
Mainframe Computers
Minicomputers
Microcomputer
Palmtop Computer
Calculator
Slow Cheap Simple Small
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32. Supercomputers
Supercomputers are the most powerful computers. They are used for handling large and highly complex problems that requires extreme calculating power
Can perform more than 1 trillion calculation per second
E.g. Cray T90 system houses thousands of processors
Because of their size and expense, supercomputers are relatively rare.
Help analyze and forecast weather, nuclear science, DNA structure (80,000~100,000 human genes), etc
Housed in a protected room with special cooling systems, power protection, and other security features
Supercomputers are used by universities, government agencies, and large businesses.

33. Supercomputers
Cray T90 Supercomputer

34. Mainframe Computers
Mainframe computers can support hundreds or thousands of users, handling massive amounts of input, output, and storage
The largest type of computer in common use
Mainframe computers are used in large organizations where many users need access to shared data and programs
Insurance companies, banks, airlines, government agencies
Mainframes are also used as e-commerce servers, handling transactions over the Internet
Are being used more and more as specialized servers on the Word Wide Web (WWW), enabling companies to offer secure transactions with customers over the Internet

35. Mainframe Computers
In a traditional mainframe environment, each user works at a computer terminal
A terminal is a monitor and a keyboard wired to the mainframe
Many enterprises are now connecting personal computers and computer networks to their mainframe systems
PCs have local storage and processing capabilities

36. Minicomputers
Minicomputers are smaller than mainframes but larger than microcomputers
Also called “midrange computers
Minicomputers usually have multiple terminals
Though some are designed for a single user
Minicomputers may be used as network servers and Internet servers
Handle data-sharing needs of other computers on the network
Dozens or hundreds of personal computers connected to a network with a minicomputer as a server

37. Workstations Workstations are powerful single-user computers
Somewhere between multi-user midrange computers and personal computers
Popular among scientists, engineers, graphic artists, etc.
Featured advanced processors, more RAM and storage capability than PCs
Until few years ago, the term workstation implied certain different in chip design and operating system, making it distinct from PCs
Workstations are used for tasks that require a great deal of number-crunching power, such as product design and computer animation
Have large, high-resolution monitors and accelerated graphics- handling capabilities
Workstations are often used as network and Internet servers

38. Workstations
Sun Workstation

39. Microcomputers
Microcomputers are more commonly known as personal computers (PC). The term "PC" is applied to IBM-PCs or compatible computers
In 1981, IBM called its first microcomputer the IBM-PC
The Apple Macintosh is another family of microcomputers
Full-size desktop computers are the most common type of PC
Notebook (laptop) computers are used by people who need the power of a desktop system, but also portability.
Handheld PCs (such as PDAs) lack the power of a desktop or notebook PC, but offer features for users who need limited functions and small size

40. Microcomputers
iMac, Apple Macintosh Computer
Horizontally-oriented PC

41. Notebook Computer, or Laptop Computers
Microcomputers
Notebook Computer, or Laptop Computers
Handheld PC
Philips Velo

42. Software Tools for Maintaining Your Computer Hardware
Chapter 3
Software Tools for Maintaining Your Computer Hardware
Utility Programs exist that can help diagnose and solve computer hardware problems
Four major problem areas where utility programs are helpful
Finding and fixing problems
Testing Input/Output peripherals
Testing RAM, motherboard, video cards
Recovering deleted files or fixing damaged disks
Improving computer performance
De-fragmenting a disk (Packs all files closer together)
Preventative maintenance
Troubleshooting
Locates incompatible programs
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