Understanding Computers Today
and Tomorrow
Some Important Characteristics of a
Computer
1.Speed
2.Accuracy
3.Storage capacity
4.Versatility
5.Providing a Capacity that would otherwise be impossible
Hardware and Software
Hardware - The physical parts of the computer
that you can see and touch
Software - Computer programs
Program -- a list of instructions to be performed
by a computer
Data -- a collection of raw, unorganized facts
Information -- data that have been processed
into a meaning form
Computer Hardware
Computer hardware typically is divided into four
categories. They are input devices, processing
unit, output devices, and storage media (harddisk drive, diskette drive, or CD drive) Input and
output devices are also referred to as peripheral
devices.
Central Processing Unit (CPU)--It is made up of the Arithmetic/Logic
unit, Control unit, and Primary memory.
Types of Computers
a.
b.
c.
d.
Small (Microcomputers or Personal Computers)
$500 - $7,000
Desktop Computers and Workstations
Laptop Computers
Notebook Computers
Palmtop Computers
Computers
Medium-sized computers (minicomputers)
$50,000 - $200,000
3 - 25 times faster than a PC
Large or Mainframe Computers
$100,000 - $2,000,000
10 - 100 times faster than a PC
Superlarge or Supercomputers
$2 million - $20 million
50 - 50,000 times faster than a PC
HW1 The Central Processing
Unit and Memory
Digital Computers -- a device that counts.
Analog Computers -- a device that measure.
•CPU -- A collection of electronic circuits.
CPU consists of ALU and Control Unit.
•ALU -- Arithmetic/logic unit
•Control Unit -- control overall operations of the
system.
Memory (Main Memory, Primary
Memory, RAM)
RAM (Random Access Memory) is a set of storage
locations on the main circuit board. It is a temporary
storage for data, programs and the operating system
while you are using the PC. It is volatile, meaning that
the contents of memory are lost forever when the
computer is shut off.
ROM (Read-only memory) consists of non-erasable
hardware modules that store program instructions. It is
nonvolatile
Computer Processing Speed and
Storage Terminology
Microsecond - one millionth of a second
Nanosecond - One billionth of a second
Picosecond - one trillionth of a second
Clock speed - MHz (megahertz) one million clock ticks
per second
Bit (Binary Digit) - The smallest unit of computer
memory -- 0 or 1.
Byte - Eight adjacent bits that represents a single
character of data.
Computer Processing Speed and
Storage Terminology
Kilobyte (K or KB) - 1024 bytes (1024
characters)
Megabyte (M or MB) - 1024K (Approximately
equal to one million bytes)
Gigabyte (G or GB) - 1024M (Approximately
equal to one billion bytes)
ASCII and EBCDIC (page HW12)
Machine language -- 0100100001001001
HW 2 -- Secondary Storage
Secondary Storage Hardware includes devices that
permanently store data and programs (nonvolatile)
Magnetic Disk
Hard disk (fixed disk)
Most PC hard disks have capacities in the range of
1GB to 2.5GB.
Diskette (soft disk, floppy disk)
5.25-inch diskette
3.5-inch diskette
DS/DD - 720 K storage capacity
DS/HD - 1.44 MB
Secondary Storage
Magnetic Tape -- A plastic ribbon with a
magnetizable surface that stores data as a
series of magnetic spots.
Optical Disk -- A disk read by reflecting pulses of
laser beams.
CD-ROM -- Storage capacities begin at 128 MB
and can exceed 1GB
HW3 Input and Output
Input Hardware (Input Devices)
Equipment that supplies data and programs to
the computer
Keyboards
Pointing devices -- Mouse, light pen, joystick etc.
Voice-Input systems -- A system that enables a
computer to recognize the human voice.
Input Hardware
Source data automation: page HW 89~95
The process of collecting data at their point of origin in
digital form.
1. OCR (Optical Character Recognition)
The use of reflected light to input marks, characters, or
codes.
2. MICR - Banking industry technology that processes
checks by sensing special characters inscribed in a
magnetic ink.
3. Digital Cameras
Output Hardware (Output Devices)
Equipment that accepts data and programs from
the computer
Display devices: An output device that contains a
viewing screen.
Monitor
CRT (Cathode Ray Tube): CRT is a TV-like video
screen used by most desktop computers
Output Hardware (Output Devices)
Printers: A device that records computer output on paper.
Impact printing: A technology that forms characters by
striking a pin or hammer against an inked ribbon,
which presses the desired shape onto paper.
Ex.: Dot-matrix printer
Nonimpact printing: A technology that forms
characters and other images on a surface by means
of heat, lasers, photography, or ink jets.
Ex: Ink-jet printers, Laser printers
Output Hardware (Output Devices)
Other output equipment
Speakers provide audio output.
Plotters provide charts, drawings, maps, and
three dimensional illustration
SW1 SOFTWARE
1. System software - Computer programs, such
as the operating system, that enable
applications programs to work with a computer
system’s hardware.
2. Application software - Programs that provide
tools for performing the type of work that
people buy computer system to do.
Windows
Windows - a box of related information that
appears overlaid on a display screen. (SW 20)
1. Cascading versus Tiling Windows
2. Resizing and Moving Windows
3. Maximizing versus Minimizing Windows
Communications Hardware
Modem (Modulator/Demodulator)
Modem is a communications device that allows
computers to exchange data over telephone
lines.
Modulator - translates computer's digital signals
to telephone's analog signals.
Demodulator - translates telephone's analog
signals to computer's digital signals.
Communication
Baud Rate - the speed of data transmission
measured in bps (bits per second). Examples:
10 pages letter is transmitted by 2400 baud rate
modem in 2.5 min., 9600 modem in 38 seconds.
Communication Software - manages
transmission of data Examples: Kermit,
SmartCom, ProComm, etc.
Access to online service - America Online,
CompuServe, Prodigy, etc.