The document discusses the typical components and configuration of modern computers. It describes the central processing unit (CPU), primary memory, and input/output (I/O) devices as the main parts. The CPU controls all computer activities and performs computations, while primary memory temporarily stores active data and programs. Common I/O devices allow entering data through keyboards, mice, scanners etc. and displaying output on monitors or printing devices. Secondary storage such as hard drives are used to permanently store large amounts of previously processed data.
2. Computer Hardware
Components
In this chapter:
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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3. Basic Concepts of Computer
Hardware
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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CPU
(Central Processing Unit)
Input
Units
Output
Units
Primary Memory
4. 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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5. 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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6. Input Devices
Two categories of input hardware:
Those that deal with original data.
Those that handle previously stored data.
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7. 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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8. 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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9. 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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10. Input Devices
Common Basic Technologies for Storing Binary
Information:
Electronic
Magnetic
Optical
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11. 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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12. 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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13. 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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14. 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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15. 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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16. Input Devices
Speed (Access time) - How fast information can be
taken from or stored onto the computer memory
devices 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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17. 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) 59.00 .50
Zip 100 (100 MB) 99.00 10.00
CD-WR (650 MB) 360.00 and up 1.00
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18. Input Devices
Capacity - The amount of information that can be
stored on the medium.
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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
19. 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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20. 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 computers use.
Volatile: All information will be lost once the computer shuts down.
ROM (permanent)
Contents do not change.
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21. 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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22. 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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23. 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.: elevators floor announcements)
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24. 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 - ReWritable)
It takes longer to write to a CD-R than a hard drive.
Special software is needed to record.
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25. 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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26. 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. 95-110 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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27. 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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28. 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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29. 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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30. 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.
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Super Computers
Mainframe Computers
Minicomputers
Microcomputer
Palmtop Computer
Calculator
Fast Expensive Complex Large
Slow Cheap Simple Small
31. 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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32. Reference
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http://www.computerhistory.org/timeline/?cate
gory=sl
http://www.eolss.net/sample-chapters/c15/e6-
45-12.pdf