CSIT111: FINALS (1st Sem)

Input Devices

• keyboard

• mouse

• image scanner

• sound input device

• digital camera

• touch screen

• drawing tablet

• optical character reader (OCR)

• optical mark reader (omr)

• magnetic ink character reader (micr)

• barcode reader

• biometric authentication device

Keyboard

the most general-purpose input device

Keyboard

When a key is pressed, the corresponding character is entered as a signal or code, most commonly ASCII code.

Mouse

an input device that detects change in movement

Image Scanner

used to scan images into a computer. Is also used as one part of a photocopier to

allow it to copy the document.

Sound input device or microphone

converts sound into digital signals using an analog to digital converter.

Digital camera

feeds images or videos taken by it into a computer.

Joystick

uses a stick moved back, forth, and around. Typically used in game consoles.

Touch screen

feeds information by touching the display screen with either a finger or a pen.

Resistive touch screens

a type of touchscreen that tends to use pens

Capacitive touch screens

the type of touch screens used in mobile devices

Drawing tablet/Pen tablet

feeds 2D drawing information as coordinate information and is used for

digital arts.

Optical character reader (OCR)

optically reads handwritten characters based on reflected light and enters them as data.

Optical mark reader (OMR)

reads portions marked on a mark sheet. Commonly used for grading

exam answer sheets with many takers.

Magnetic ink character reader (MICR)

reads characters written in a special font in magnetic ink.

Barcode reader

reads barcodes, typically those used by point-of-sale (POS) systems.

One-dimensional bar code

the typical bar code. Typically uses EAN-13 in encoding.

Two-dimensional bar code or QR code

matrix-based bar code using patterns of small squares within a larger square. It can be scanned using a mobile device.

Card reader

used for reading information recorded in a card.

Magnetic card reader

used for reading magnetically recorded information, such as a debit or credit card. The black stripe on debit or credit cards is the one read by these readers.

IC card reader

most common example of that is an RFID card reader or the ones for key cards used in hotels.

Biometric authentication device

feeds information for biometric authentication. Common biometrics include fingerprints, irises, faces, and even voice.

Display or monitor

device that displays images in color by combining three primary colors of light:

red, green, and blue (RGB).

Screen resolution

the density of dots or pixels on a screen. Units of resolution are commonly dots per inch or pixel sizes.

Aspect ratio

the ratio of width to height on a screen. Common of these for screens

are 4:3, 16:9, and 16:10.

Types of Displays

• Cathode ray tube (CRT)

• Liquid crystal display (LCD)

• Light emitting diode (LED)

Cathode ray tube (CRT)

these are bulky and heavy monitors and were quite inefficient and prone to screen burn-in, hence the need for screensavers.

Liquid crystal display (LCD)

these are thinner displays and use liquid crystals with a backlight.

Light emitting diode (LED)

use compounds that emit light when voltage is applied. A variant of this is the organic light emitting diode (OLED) display which uses organic compounds.

Printer

used for printing characters onto paper. most printers use four cholors and print characters and images as an aggregation of dots. Print resolution is measured in dots per inch (dpi).

Cyan Magenta Yellow Black (CMYK)

four colors most printers use

Types of Printers

• Impact Printer

• Thermal Printer

• Thermal wax transfer printer

• dye sublimation thermal transfer printer

• inkjet printer

• laser printer

Impact printer

prints by mechanically striking ink ribbon on paper with a print head. It is

quite noisy but can print multiple copies at the same time by placing carbon paper.

Thermal Printer

uses heat and special heat-sensitive paper. Commonly used for receipts.

Thermal wax transfer printer

transfers waxed colored ink applied on the ink ribbon of four colors (CMYK) by melting with heat

Dye sublimation thermal transfer printer

uses sublimation dyes mounted on a film to convert dyes directly to gases absorbed by special paper. Commonly used in shirt printing.

Inkjet printer

the most common type of printer. Uses jets of air to blow dots of ink onto the paper.

Laser printer

affixes toner or powdered ink to a photoconductive drum using a laser, then transfers the toner to the paper.

Plotter

prints graphics and is used for printing drawings such as blueprints created with computer aided design (CAD)

Projector

used for enlarged projection of display images on large screens.

Speaker

converts digital data to analog signals using a digital to analog computer (DAC)

Information system

computer system within a company or organization for

Client

receives services. Includes terminal devices such as end-user PCs.

Server

provides services.

Processing Modes

Centralized processing

Distributed processing

Centralized processing

all processing on one computer

Distributed processing

processing is divided between computers on a network

Systems Administrator

takes care of the systems others are using. They keep the system running smoothly and efficiently to allow users to perform work more efficiently and more easily.

Reliability, Availability, Serviceability, Integrity, Security

RASIS stands for:

Reliability

normal operation time or “up time” of the system. Can be improved by ensuring the system remains operational with no functions coming to a halt during operation.

Reliability

(RASIS) Computed as the mean time between failures (MTBF).

Availability

maximum possible usage ratio of the computer system. Computed as the ratio of up time to total running time.

Serviceability

ease of maintenance of the system. Computed as the mean time to repair (MTTR) or “down time”.

Integrity

ability to prevent data corruption.

Security

ensuring security of data.

Series, Parallel

System Types

Series

Operates only when all devices from which it is configured are operational. Availability is computed as a product of the availabilities of all devices.

Parallel

Operates as long as at least one device is operational.

System software

enable effective use of computer hardware.

Operating System (OS)

fundamental system software

Control program

allows the computer to boot into the OS.

Utility programs / Service programs

provide standard functions such as file management and disk management

Middleware

software located between the OS and application software

Shell

interprets user operations with a command interpreter or command line

interface. Windows PowerShell is an example of this, as is Command Prompt.

Application Programming Interface (API)

mechanism for using the features provided by an OS from an application program.

Web API

enables use of functions useful for creating web content

Library

groups programs with highly versatile and specific functions in a reusable

format.

Dynamic Link Library (DLL)

incorporated by the OS during execution of a program.

Application software

provides functions needed by users

Individual application software

Common application software

Types of application according to aims of usage:

Individual application software

custom-made (type of application)

Common application software

widely-available but can still be customized to a certain extent. (Type of application)

Office suite

hosts basic function required in office or academic settings (common application software)

Word processing software

common application software for creating documents

Spreadsheet software

common application software for creating tables or calculations

Presentation software

common application software for creating presentation materials

Desktop publishing software

common application software for creating digital and print materials

Notetaking/Personal knowledge management

common application software for notes and storing personal knowledge

Database software

common application software used for creating, using, and managing databases. It also allows simple data processing programs using a dedicated language.

Formula editor

common application software used for creating and editing mathematical formulas.

Diagram creation software

common application software used to create diagrams.

Cloud file management software

common application software used to manage files stored on the Internet.

Groupware

common application software supports joint activities of an organization with computers, such as e-mail, digital conferencing, schedule management, and workflow management.

Graphics software

common application software used to create and handle graphics and images on a computer.

Windows

Linux

Mac OS

Common operating systems for PCs

Windows

OS developed by Microsoft

Linux

lightweight OS useful for PCs with a low amount of resources

Mac OS

developed by Apple for its own PCs.

iOS, Android

Common mobile operating systems

Android

based off Linux. Available in most modern phones and tablets.

iOS

developed by Apple for its own mobile devices (iPhone and iPad)

Management functions of operating systems

• Job management

• Task management

• Task Manager

• Memory management

• Data management

• Input/output management

• Network management

• User management

• Security management

• Fault management

Software license

describes rules for using the software. Generally included in the end user license

agreement or EULA (which we tend to ignore).

Packaged software

commercially available to the general public, commonly for a fee.

Paid software

distributed with charge over networks.

Shareware

has a free trial period, after which the user can opt to pay if they wish to continue.

Free software

distributed free of charge over networks.

Open-source software

source code is freely available and is commonly maintained by a community of volunteer developers rather than one developer or company alone. Common open-source software includes the Linux OS, Google Chromium, LibreOffice, and the GNU Compiler Collection (GCC for C, GPP for C++).

Common open-source software licenses

- GNU General Public License (GPL)

- GNU Lesser GPL

- Mozilla Public License (MPL)

- Apache License

- MIT License

Cloud computing

a system where users easily receive services via a network, commonly the Internet.