Types of Computers
Personal Computers Mainframes
Smart Phones
Wearables
Embedded Systems (Car, Elevator, Aircraft) Game Consoles (X Box, Play Station, Switch) Television
Sets
DVD Players
Set Top Boxes (from Flow, Digicel, Amplia)
How a Computer Represents Data
Computers use the presence or absence of electrical or
magnetic signal to represent data. In the current is ON a computer uses a 1. If the current is off, the computer uses a 0.
This is the basis of the Binary System. Thus a computer can use a sequence of eight 1s and 0s to represent an individual letter, number or special character.
Components of a computer
Central Processing Unit
Primary Storage
Secondary Storage
Communications Devices
Input Devices- Keyboard, Computer mouse, touch screen and source data automation
Output devices- printers, video display terminals, plotters and audio output
Secondary storage
Magnetic Disk
RAID Systems
Storage Area Networks
Input Devices
Keyboard
-Main device for text & number entry.
Computer Mouse
-Hand-held pointing device (point & click).
-Usually wired to the computer.
-Moves cursor on screen, selects commands.
-Variations: Trackball & Touchpad (common on laptops).
Touch Screen
-Input/output device.
-User taps/points directly on the display surface.
-Common uses: information kiosks, retail stores, restaurants, shopping malls.
Optical Character Recognition (OCR)
-Converts specially designed marks/characters into digital form.
-Common use: banking industry (e.g., cheques).
-Preprinted info (line, date, ID) is read and digitized.
Magnetic Ink Character Recognition (MICR)
-Reads characters printed with special magnetic ink.
-Example: bank cheque processing.
Pen-Based Input
-Uses a stylus on tablets/notebooks.
-Recognizes handwriting and converts it into digital data.
Digital Scanner
-Converts images/documents into digital form.
-Audio Input
-Converts human speech into digital data.
-Devices: microphones, sensors.
Sensors
collect data directly from the environment for input into a computer system.
Example (Agriculture): Farmers use soil moisture sensors to monitor fields & assist with irrigation.
Other examples:
Temperature sensors (weather stations, fridges).
Motion sensors (security systems).
Light sensors (automatic lights, smartphones).
Output devices
Cathode Ray Tube (CRT)
Electronic gun shoots a beam of electrons illuminating pixels on a display screen.
-Used in older monitors.
-Laptop computers now use flat panel displays, which are less bulky than CRT monitors.
Printers
-Produce printed hard copy of information output.
-Impact printers: e.g., dot matrix printers.
-Non-impact printers: e.g., laser, inkjet, thermal transfer printers.
Audio Output
-Voice output devices convert digital output data into intelligible speech.
-Other audio (e.g., music) can be delivered by speakers connected to the computer.
Microfilm & Microfiche
-Used to store large quantities of output as microscopic filmed documents.
-Being replaced today by optical disk technology.
Computer Network Architectures-Centralized
Computers networks are normally set up in one of two modes. They are either centralized or decentralized. In a centralized mode all the processing takes place on the central host. Terminals and printers are the primary input and output devices. While the terminal can look very much like a PC, unlike a PC, a terminal has little processing capability of its own. Mainframes and minicomputers are found at the heart of centralized networks.
Computer Network Architectures-Decentralized
In decentralized systems processing is distributed to many computers in the network. Two popular forms of distributed processing include the client-server model and the peer to peer model. The computer networks on campus are based on the client server model. Data is stored on the server, but most processing is handled locally. SETI uses the peer to peer model to process radio signals from space.
Data and Processing is done on the local computer.
Software
All computers need software to function. This software can be embedded with the hardware at the time of manufacture. More commonly, the software can be installed on the computer at any time. The ability to add and upgrade software adds to the flexibility of the system.
Two main types of software are
-Systems Software (Operating System)
– Application Software.
Systems software
controls the allocation of
resources and the scheduling of tasks on a computer. The system software also keeps track of where data is at any given time.
Process of systems software
The systems software “sits” between the application
software and the hardware.
Applications software request resources from the
system software. The systems software passes these
requests onto the hardware and then return the hardware responses to the application software. This frees the application programmer to
concentrate on solving a specific problem (payroll processing) without having to worry about
hardware interfaces. This specialization improves
productivity
Application software
is designed for a specific job.
– Payroll Processing
– Human Resource Management
– Accounting
– Word Processing
– Computer Aided Design (CAD)
– SCM, ERP, CRM, KM
The focus of application software is the user. System
software focuses on managing the hardware.
Types of application software
Personal Productivity Applications
* Enterprise Applications
* Development Tools
Personal Productivity Applications
The focus of personal productivity applications
is on the individual user.
– Word processing (Word, WordPerfect)
– Spreadsheets (Excel, Lotus 123)
– E Mail (Outlook, Eudora)
– Browsers (Internet Explorer, Opera)
– Presentation Managers (PowerPoint)
– Graphic Design (Freehand, Illustrator)
– Computer Aided Design (AutoCAD)
Enterprise software
Enterprise class applications focus on improving the efficiency and effectiveness of
the organization as a whole.
– Enterprise Resource Planning
– Supply Chain Management,
– Customer Relationship Management
– Knowledge Management
Development tools
used to create systems
and applications software.
– Programming Languages
– Compilers
– Database Management Systems
– Web Development Packages
– Query Languages
Programming- the programmer
a programmer chooses a language that is designed for a specific task. The programmer writes the program based on
the “syntax” of that language.
In order to test the program it must be “compiled” into machine readable code (1s
and Os) and “debugged
Evolution of Programming Languages
First Generation = Machine Code
* Second Generation = Assembler
* Third Generation (Fortran, Basic, Pascal,
COBOL, C, C++)
* Fourth Generation (SQL, ADA, Focus)
Other development tools
HTML
* XML
* XHTML
* JAVA
* JavaScript
* Flash
* ASP, ASP.NET, JSP, PHP
* Cold Fusion
