INTRODUCTION TO COMPUTER SYSTEM

Advantages of Custom-written Software over Off-the-Shelf Software

1) CWS - Designed specifically for the task and will meet all the customer's requirements; need not be adapted OTSF - Needs to be adapted specifically to meet each customer's requirements; can be very difficultv

Disadvantages of Custom-written Software over Off-the-Shelf Software

1) CWS -Can be costly (payment to programmers who write the software) OTSF-Cheaper to buy (mass-produced)

Some types of PCs

1) Desktop computers - small enough to fit on top of or alongside a desk, too big to carry around 2) Laptop computers - portable and lightweight computers that fit into most bags and briefcases (includes netbooks, hybrid 2-in-1)

Disadvantages of laptop computers when compared to desktop computers:

1) Easier to lose and/or misplace 2) Limited battery life; requires carrying around a power adapter

Key features of laptop computers:

1) Lightweight (to aid portability) 2) Low power consumption (and long battery life) 3) Low generation of heat from processor (cooling is very important)

Types of Computers

1) Personal computers (PCs) 2) Mobile computers 3) Wearables 3) Supercomputers 4) Mainframe computers 5) Mid-range computers (or servers)

Advantages of laptop computers over desktop computers:

1) Portability; can be taken anywhere, everything is in one single unit 2) No trailing wires

Examples of wearables:

1) Smartwatches (e.g., Apple Watch, Android Wear) for fitness tracking 2) Pet monitoring using chip implantation

Components in Motherboard

1) Socket/ Port 2) Chips 3) Slots 4) Buses

Advantages of desktop computers over laptop computers

1) Spare parts and connections tend to be standardized - results in lower costs 2) Desktops tend to have better specifications for a given price (often due to size and construction constraints in laptops) 3) Power consumption is not critical since they plug straight into a wall socket and larger casings allow for a better dissipation of any heat build-up 4) Less likelihood of being damaged (due to being usually stationary in one location)

Characteristics of a good UI:

1) User-friendly - allows users to communicate with the computer without encountering any problems 2) Intuitive - users should be able to predict what will happen if they take a certain action

Advantages of Custom-written Software over Off-the-Shelf Software

2) CWS - Alterations to the software can be made by the programmer who is readily available if software does not meet requirements OTSF - Can be difficult to find a programmer who is readily available to make software alterations

Disadvantages of Custom-written Software over Off-the-Shelf Software

2) CWS -Limited support options - restricted to programmer/team of programmers who created the software OTSF-More support options - likely to be forums or websites to help users, or telephone helplines with experienced operators

Advantages of Custom-written Software over Off-the-Shelf Software

3) CWS -Will contain all the functions as required by the customer without any unnecessary features included OTSF -May not contain all the functions as required by the customer while being possible that it will include unnecessary features

Disadvantages of Custom-written Software over Off-the-Shelf Software

3) CWS -vSoftware development can be time consuming OTSF-Immediately available, as it has already been written

Information processing cycle

4 stages in the Information Processing Cycle 1) input 2) process 3) output 4) storage

Disadvantages of Custom-written Software over Off-the-Shelf Software

4) CWS -Bugs may be more prevalent as it may not have been tested as thoroughly OTSF-More likely to be more secure; usually tested rigorously

Advantages of Custom-written Software over Off-the-Shelf Software

4) CWS- Compatibility with current computer system (hardware or OS) being used assured OTSF- Compatibility with current computer system (hardware or OS) being used not assured

Advantages of Custom-written Software over Off-the-Shelf Software

5) CWS- Customer owns copyright of the custom-written software; able to sell software to others OTSF- Even if adapted, customers are not allowed to sell software to others (violates software company's copyright)

Processor

A device that carries out computation on data by following instructions, in order to produce an output. • Handles the instructions that it receives from the user and from the hardware and software • Performance is measured in clock speed ( processing speed, number of times the CPU fetches and processes days or instructions in a second ) e.g pressing 'A' on keyboard 1) sends an electrical signal to the USB port at the back of the computer 2) signal is the routed through the processor 3) processor recognizes signal 4) processor sends another signal to the monitor to display 'A'

More about CPU

CPU used to be made of discrete components and numerous small integrated circuits ( these were combined together on one or more circuit boards ) • However due to modern manufacturing techniques the CPU is now referred to as microprocessors • CPU is made of 1) control unit 2) arithmetic logic unit 3)small memory locations called register

Control unit

ensure synchronization of data flow and program instructions throughout the computer

Register

make up the RAM ( act as an immediate access store )

FM synthesis

mimics different musical instruments according to built in formulas

Disadvantage of CLI

misspellings from typing in commands will cause the system to fail to perform as desired (clumsy and confusing interface)

Output

processed data or information

System Software

programs that run and control a computer's hardware and applications software

Application software

programs used by regular uses to complete a particular task ( I. e this is what the users use their computer for )

Slots

provide a connection point for specialized cards or circuit boards

Storage device

records ( writes ) and/or retrieves ( read) items to and from storage media.

Wavetable Synthesis

relies on recordings of actual instruments to produce sound

Wearable Technology

s a category of electronic devices that can be worn as accessories, embedded in clothing, or implanted in the user's body.

Read Only Memory

stores data and can be read from but not written to ( unless programmable ROM )

Random Access Memory

stores data and can be read to and written from

Refer to page 38 of lecture notes

to see the example compilation of c++ code

Backup Software

used to keep copies of files from a computer or copy the content of a server's backing storage

Immediate Access Store

where data is stored on the main computer memory

Main disadvantage of desktop computers when compared to laptop computers: portability

will require copying files from desktop to a portable computer, or move the computer in order to work in a different location

Operating System

• A collection of software designed to act as an interface between user and the computer and manages the overall operation of the computer • Links the hardware, applications and user together but hides the true complexity of the computer from the user and other software -- so called virtual machine • Users are more aware about application software being used, but less aware of software running in the background • System Software is dominated by the OS • OS is often large and would occupy too much ROM, most of it stored in hard disk instead and the instructions for loading OS is left in the ROM ( executed when computer is turned on )

Virtual Assistance

• Accepts commands through text or speech to allow intuitive interaction with the computer, smartphone or tablet and coordinate personal data across multiple applications

Sound card

• An integrated circuit board that provides a computer with the ability to produce sounds • Also allows users to record sound input from a microphone connected to the computer and to manipulate sounds stored on a disk • Sounds can be heard by user either through speaker or headphones • uses 2 basic methods to translate digital data into analog signals ( needed for speaker ) 1) FM synthesis 2)Wavetable synthesis ​

Library Programs

• Are like utility programs in that they are written to carry out common tasks • The word library indicates that there will be several software tools available to users of the system • However while some utility programs are nonessential, library programs tend to be critical for applications for which they were built • Examples: 1) Dynamically Linked Library files in Window 2) Python's Library of modules for handling common data types, performing mathematical operations etc

Mobile Computers

• Are smaller, lighter, and generally less powerful than most personal computers. 1) Smartphones - most widely used handheld computers - cellphones with wireless connections to the Internet and processing capabilities 2) Tablets -typically a mobile device with a touchscreen sometimes as big as a laptop's screen, and lacks the diversity of I/O abilities of a PC -interactivity by touch or stylus

Computer system

• Basic, complete and functional hardware and software setup with everything needed to implement computing performance • The term " System " is often used to refer to various physical components of your computer ( e. g monitor, keyboard etc ) • A computer system has 2 main elements ( hardware and software ) • It is only when the two are combined that you create a fully working system • Some definition of a computer system add in a third vital element, the " user "

Interpreters ( continue )

• Compiling a program uses more memory than interpreting it ( compiling requires whole program to be loaded before translation whilst only a fraction of that memory is required to interpret a few statements/lines of code ( beneficial for software testing ) ) • with an interpreted program, source code musy be always available because it is liable to risks with software copyright infringement or intellectual property rights ( compiled program is essentially translated into machine code, which is difficult to understand and alter )

Hardware

• Computer hardware refers to the physical components of the computer ( sometimes this is described as the parts you can touch however this is not helpful as many elements of hardware are contained inside your computer and can only be seen or touched by taking off case ) • Computers typically contain the following major components 1) input device 2) output device 3) system unit 4) storage device 5) communication device • Divided into 2 categories: 1) external hardware ( peripherals) ( i.e touchable parts ) - input/output device ( e.g mouse , keyboard , joystick ) - external storage device ( e.g external HDD flash drive ) 2) Internal hardware ( processing and storage ) ​

Control bus

• Controls the flow of data between the processor and other parts of the computer, bi-directional

Graphic coprocessor/ Graphic Processing Unit

• Designed to handle a variety of specialized tasks such as displaying 3D images and encryptibg data •Powerful GPU are a standard feature in gaming computer to support fast processing of virtual environments

Buses

• Groups of parallel microscopic wires that connect the processor to the various I/O controllers being used by the computer • Also used to connect the internal components of a microprocessor ( known as registers ) and to connect the mircroprocessro to memory • Microprocessors ( can be found in computers ) are made up of microscopic electronic circuits and belong to a group of devices commonly referred to as chips • 3 types of busses 1) data bus 2) address bus 3) control bus ​

User Interfaces (UI)

• Is the means by which the computer system interacts with the user • Enables the user, with the help of input devices, to communicate with the computer and then, via the OS, communicate with a piece of software or any output device • Major interfaces include command line interface (CLI), graphical user interface (GUI), dialog interface, and gesture-based interface.

Major Functions of OS

• Manage computer's memory allocation between applications, system software or utility software • Manage data input and output, communicates with device drivers to retrieve data or send data/instructions • Manage storing of files on and loading of them from backing storage • Allocate time to each task or program fairly so that all tasks or programs get a reasonable amount of time • Display error messages to the user should an error occur which requires the user to intervene • Manage users on a network ( it maintains the list of usernames and passwords and controls which files and resources users have access to ) • Make sure that computer shuts down properly when finished

Compression Software

• Modifies data so that it occupies less storage space on a disk

Troubleshooting and Diagnostic software

• Recognizes and corrects probelms ( ideally before they become serious )

Computer Aided Design

• Software meant for design and technical documentation, which replaces manual drafting with an automated process • used mainly to draft constructions documentation , explore design ideas , visualize concepts through photorealistic rendering and stimulate how a design performs in the real world

Off-the-Shelf Software

• Software that already exists and is available right away, ready for use. • If the company with a new computer system is a smaller company, it may turn to one of the large software companies that already produce business software packages (e.g., invoicing software, accounting software, payroll software) that are available to all business, organizations, and the general public. • Such programs may provide desired features (e.g., text editing, accounting functions, mail merge).

Custom-written Software

• Software that is written specifically for a particular task. • Typically developed for a specific company or business Examples of reasons for developing custom-written software include: 1) Require databases to be designed which require specialist programming skills 2) require a website to be created which it wants to have tailored to its own needs

Compilers

• Software that processes statements written in high-level programming language and converts them into machine language or code that a computer's processor undertsands and can execute • Translates a high level language program ( I. e source code ) into an executable code ( I. e object code/ byte code ) • Compiled program is then run directly without the need for the compiler to be present

A notes about Compilation and Interpretation

• Some high level languages like Python or Java can be translated using a combinatiin of compiler and interpreter • Possible for program to be translated or compiled what is called " bytecode" • Bytecode is then processed by a program called "Virtual Machine" which often acts as an interpreter instead of by the processor within the computer • Diagram in lecture notes page 36

Virtual Machines

• The concept that all complexities of using a computer are hidden from the user and other software by the OS

Data bus

• Transfers data between the processor and memory, bi-directional • carries the data both to and from memory and to and from I/O controllers

Interpreters

• Translates the high level program one statement or line at a time into a intermediate form which it then executes • Continues translating program until the first error is met, at which point it stops ( allows programmers to pinpoint the error source immediately rather than wait for whole program to compile, debugging is easier ) • This conversion needs to be done each time a statement is executed ( can become a lengthy process the more times conversion needs to occur ) • Compiled program only runs on a computer whose OS is the same as the one where it was compiled • Interpreted program will work on any computer with the appropriate interpreter ( since it will still be in its original source code )

Choosing An Appropriate UI

• When selecting an appropriate UI for a use case scenario, consider the user group who is going to use the software or system. For example: 1) Disabled users may not be able to benefit from certain UIs (e.g., the blind will not benefit from a GUI, paralysis patients with CLI) 2) Noisy situations are not ideal for using dialog interfaces 3) If software or system is to be used in a setting where hygiene is of utmost concern (e.g., ICU room), any interface that requires touch is not ideal, but gestures are okay 4 ) Experienced users may not be able to be as productive with a GUI that limits built-in functionality, whilst beginners can get overwhelmed with a complex CLI interface

Software

• a general term used to describe all the programs that we run in our computer • these programs contain instructions that the processor will carry out in order to complete various task • Software can be divided into 2 categories 1) application software 2) system software

Linkers

• a linker ( link editor ) is a program that combines object files or modules that have been created using a compiler into a single executable file • Combines different modules of object code into one executable code program 1) perhaps a large program could be only compiled in small parts due to lack of RAM to hold the whole program and the compiler program 2) parts of the program can be stored on backing storage and then one at a time each part is brought into the RAM and compiled 3) Resulting object code is then saved to the backing storage 4) After all parts have been compiled, they are brought back into the RAM and the linker can be used to combine them into the complete program Advantage: program can written in modules which require less RAM, saves cost Disadvantage: Conflicting variable names may occur between modules ( I.e multiple modules have a variable named the same but for different purpose )

Motherboard (system board)

• a printed circuit board that allows the processor and other computer hardware to function and communicate with each other • function as a 'hub's that other computer devices connect to • contains the central processing unit, the part of the computer that interprets and executes commands from the computer hardware and software ​

Device Drivers

• a small program that enables the OS and application software to communicate with hardware device • e.g printer driver acts as an interface between the OS / any running software application and the printer 1) user wants to print information 2) application tells printer driver. 3) printer driver tells printer this, in effect allows user to have control of the device • Most modern OSes are supplied with many drivers that allow hardware to work at a basic level

Utility Program / Software

• a type of system software that assists users in controlling or maintaining the operation of a computer, its device or its software • required to manage the allocation of computer memory in order to improve the computer's performance so that users can customize the appearance of their desktop • Examples include: 1) antivirus software 2) backup software 3) compression software 4) troubleshooting and diagnostic software 5) virtual assistance

Video Editing Software

• allow users to manipulate videos to produce an edited video • enables addition of titles color correction and altering/ adding sound to the original video • which includes: 1) rearranging adding and removing sections of video clips and audio clips 2) applying color correction, filters and other video enhancements 3) creating transitions between clips in the video footage

Graphic Editing Software

• allows bitmap and vector images to be changed • Differences between bitmap and vector graphic editors: 1) Bitmap images are made up of pixels that contain information about image brightness color. Bitmap graphic editors can change the pixels to produce different images 2) Vector graphic editors on the other hand manipulates lines, curves, and text to alter stored image as required

Dialog Interface

• allows users to communicate with a computer or device using their voice. • computer can use speech-recognition software to convert the spoken word into commands it can understand • requires learning the way how the speaker talks by asking the user to repeat certain sentences until it has 'learnt' the way they speak • background noise and ability to recognize only a limited vocabulary can cause problems (may misunderstand what is trying to be said)

What is a Computer?

• an electronic device that can follow instructions to accept input, process that input and process information ( output) • A computer is any machine or device that processes days. • Figure in lecture page 4 shows the information processing cycle carried out in computer system

Game Consoles

• are electronic or computer devices that outputs a video signal or visual image to display a video game that one or more people can play through some type of game controller. 1) home consoles - generally placed in a permanent location connected to a display device (often a television) and controlled by a separate controller 2) handheld systems - include their own display unit and controller functions built into the unit; can be played anywhere

Database Management System (DBMS)

• are used to organize, manipulate and analyze data • a typical database is made up of one or more tables • tables consists of rows and columns • Some functions include: 1) ability to carry out queries on database data and produce a report 2) add, delete, and modify datas on a table

Chips

• consist of tiny circuit boards etched onto squares of silicon. • also called silicon chip, semiconductor, or integrated circuit • mounted on carrier packages ( something like cover or case ) ( i.e these carriers plug directly into sockets, or onto cards that plugged into slot on the system board )

I/O controller

• controls the flow of information between the processor and the input and output devices •I/O devices are connected via I/O ports • Data buses carry the signals to and from processor ( processor communicates through I/O controller interface and not directly with I/O devices ) • key feature : translates signals from device to the format required by the processor ( gives flexibility to add new devices without having the need to redesign the processor )

Control Management Software

• designed to allow a computer or microprocessors to interface with sensor so that is possible to 1) measure physical quantities in the real world ( such as temperatures ) 2) control application ( such as chemical processes ) by comparing sensor days and sending out signals to alter process parameters ( e. g open a valve to add acid and change PH.)

Command Line Interface (CLI)

• is a means of interacting with a computer using commands in the form of successive lines of text. • a prompt appears on the screen to which the user responds by typing a command • output from the computer could be to produce a list or take some other action

Gesture-based Interface

• is designed to interpret human gestures and convert these into commands. • Gestures can be made with any part of the body, but it is usually the face or the hand that makes the gestures the computer can interpret. ( e.g., in 'smart' homes, a gesture can turn on the lights ) • In this area of IT, a gesture can be said to be any physical movement, large or small, that can be interpreted by a computer. • The computer, using a special type of software, searches through all the gestures it has stored in a database to match it with the input. • Each stored gesture is linked to a specific command which is then executed after the gesture has been matched.

Mobile Apps

• normally refer to the type of software that runs on cell phones and tablets • mobile apps are usually downloaded from an App Store and range from games to sophisticated software such as phone banking • common examples include: 1) video and music streaming ( e. g YouTube, Spotify ) 2) global positioning system which together with satellite navigation helps find route to a chosen destination 3) camera facilities ( taking photos and stroring / manipulating the images taken ) ​

System Software General features

• set of programs to control and manage the operation of computer hardware • provides a platform on which other software can run • required to allow hardware and software to run without problems • provide a human computer interface • Controls the allocation and usage of hardware resources

Main Memory

• stores data and instructions that will be used by the processor • two types of main memory 1) Random Access Memory 2) Read Only Memory

Word Processing Software

• used to manipulate text documents such as essay or report • Function includes: 1) creating, editing, saving and manipulating text 2) copy and paste function 3) spell checkers and thesaurus 4) importing photos into a stuctured page format 5) translation into other languages

Spreadsheet Software

• used to organize and manipulate numerical data ( in the form of integers, real numbers, data etc. ) • Functions include: 1) use of formulas to carry out calculations 2) ability to produce graphs 3) ability to do modelling and 'what if ' calculations

Application Software General Features

• used to perform various application on the computer • allows a user to perform specific tasks using the computer 's resources • may be a single program ( E.g notepad ) or a suite of programs ( Microsoft Office ) • user can execute the software as and when required

Address bus

• used to specify a physical address in memory so that the data bus can access it, one way from the processor to memory

Graphical User Interface (GUI)

• uses windows, icons, menus and pointers (collectively known as a 'WIMP' interface) to carry out commands. • created as a less inefficient means of communicating with the computer • users interact with the WIMP interface using input devices

Coprocessor

•a microprocessor designed to improve specific computing operations •many cars have more than 70 seperate specialty processors to control nearly everything from fuel efficiency to satellite entertainment and tracking systems

Storage

Information that is stored for future use and retrieval

Antivirus Software

a program or set of programs whose function is to detect and remove viruses

Microprocessors

a single integrated circuit which is at the heart of most PCs and is also found in many household devices and equipment where some control monitoring is needed ( e.g engine management system in a car )

Process

action or routine performed by computer to convert input to output

Input device

allows users to enter data and instructions into a computer

Personal Computers (PCs)

are the least powerful, yet the most widely used and fastest-growing type of computer

Arithmetic logic unit

carries out calculations and makes logical decisions ​

System unit

case that contains electronic components of the computer that are used to process data

Socket/Port

connection point for chips

Dynamically Linked Libraries files in Windows

contain code, data and resources for carrying out actions including controlling dialog boxes, managing memory , displaying text and graphics, configuring device drivers

Output device

conveys information to other user

Input

data or instructions that are entered into a computer

Communication Device

Enables a computer to send and receive data, instructions, and information to and from one or more computers or mobile devices.