1.2 System Design Basics

Physical, tangible elements of a computer system (e.g CPU, HDD)

Set of instructions for the CPU to preform specific operations, comprised of both programs and data

Auxiliary device that can connect to, communicate and work with the computer (e.g input/output devices, printers, etc.)

Set of computer systems that are interconnected and share resources as well as data

People who are used or could be used in organization, business, or economy.

A device that usually consists of a keyboard, a monitor, and a network card that is connected to a server or a powerful computer. Dumb terminals depend entirely on the computer to which they are connected for computations, data processing, and data management

Relatively low performance terminal, which heavily but not entirely, depends on the server to which it is connected

Receiving data via the network, whereas the server has saved data on it and offers this to clients. It accesses services made available by server, by sending requests to the server

Program/host computer that fulfills requests from client programs or computers across network and shares info to clients

Message transfer agent that transfers electronic messages from one computer to another in a network

Server that translates web addresses written in letters (more memorable for humans) to the numeric IP (internet protocol) address

Connects networks together to forward data packets between networks, deciding where to send information from its destination address and routing policy

Attributes names to network addresses and therefore allows users to input string names instead of numerical IP address

Controls incoming and outgoing network traffic, determining what data packets should be allowed through, based on a rule set. Needed to protect the integrity of client computer

Software network architecture system where clients request information and servers perform tasks in order to provide the information. At least one server machine is required as a prerequisite for the client-server architecture. The main difference between server and clients is that servers share their resources whereas clients do not

Refers to how well an IT system functions. Computer failures cause data loss, time loss, money loss, injury, or even death. The reliability of IT systems determines confidence in their value

Refers to protecting the completeness and accuracy of data. Data lacks integrity if it is incomplete, out of date, or has been purposely or unintentionally altered

Problems may also arise if information is duplicated in a database and only one copy is updated, causing inconsistency (e.g. telephone field)

Refers to the protection of hardware, software, peripherals, and computer networks from unauthorized access. Biometrics, proprietary tokens, passwords, firewalls, and locks are some of the most common security systems placed to restrict access to IT systems.

Involves a person proving their identity to gain access to a computer system beyond reasonable doubt. it is important to mention that requiring more than one independent factor increases the difficulty of providing false credentials

The ability to control how and to what extent data is used and disseminated to others. It includes issues such as: how long data is stored, who was access to the data, and how the data is used.

Privacy becomes anonymity when, for instance, an individual uses an IT system to conceal his/her true identity in order to cyberbully another person, commit illegal actions or crimes, hack computers, or commit terrorism, etc.

Refers to ideas, discoveries, scientific endeavors, photographs, films, essays, and art works. Copyright laws are designed to protect intellectual property from unauthorized and illegal reproduction. Modern “copy and paste” and file-sharing practices and devices make it easy to break copyright laws.

The growth and the use of IT systems have not developed at the same rate for everybody in all parts of the world, or in all areas of the same country. Even within advanced countries there are people who lack access to IT infrastructures, and online services. Economic costs, financial costs, lack of literacy, lack of language skills, and lack of basic resources such as electricity are the main reasons that sustain the digital divide

Using IT to monitor individuals or groups of people either with or without (also a privacy issues) their knowledge or permission. Governments, law enforcement, private groups, employers, traffic control, etc. may perform surveillance.

IT helps to diminish the importance of geographical, political, economic, and cultural boundaries while speeding up the global, financial, sport, and cultural news. Traditional cultures and values may diminish gradually over time.

• May diminish traditional cultures

An authentication technique used to control computer access. Use must exhibit at least two out of three categories.

1. Knowledge factors: “things only the user knows”, passwords

2. Possession factors: “things only the user has” , ATM Card

3. Inherence factors: “things only the user is”, biometrics

Enforceable procedures and measures that promote the appropriate use of computers, networks, information systems and technologies. Governments, public authorities, local authorities, businesses, private groups or individuals are developers of various IT policies. The fast pace of information technology progression means policies often quickly made obsolete.

Predefined technical rules and conventions that developers of hardware and software should follow. Standards and protocols allow for compatibility, facilitate communication and interoperability. They are needed to ensure different systems are compatible with each other

Internet addiction is a social impact. The use of AI in military or law-enforcement situations is also an issue of social concern. This subject analyzes all aspects of the interaction between IT and humans

Individuals, teams, groups, or organizations that have an interest in the realization of a project or might be affected by the outcome. Any person who has interests in an existing or proposed information system can be described as a stakeholder of the system

The person who is going to use the product. A relevant stakeholder can also be a frequent user of the current system. He/She will be able to identify flaws and errors of the current system or inconveniences that he/she has spotted. They will be able to propose some improvements that will be crucial to the update of the system.

1. Saving in fuel cost and commuting time

2. An opportunity to work at your own pace (more comfortable, therefore increased productivity). Also able to work in an undisturbed environment, choose their own work hours

   1. Convenience of not having to travel

1. Employees can clam the employees are part time consultants or the like to avoid paying benefits like insurance, medical plans, taxes

2. Stain on families that result when a family member works from home

3. At-home employees miss interaction with co-workers at the office

4. At-home employees think they work too much, employers think they do not work enough

5. Employees cannot monitor employees, expensive of setting up a VPN

How consistently a computer system functions according to its specifications with minimal system failure. Failures result in data, time, or revenue loss

Maintenance of accuracy and consistency of data. Must be complete, up-to-date and unaltered. Inconsistent if theres data duplication/redundancy

Rules followed in development of systems, including proprietary standards (e.g. computers compatible with Microsoft operating systems), industry standards, and ‘de facto’ standards

Face-to-face with verbal responses. Can be structured with the same questions and manner for every stakeholder, or unstructured with more flexibility

1. Talk directly to users/members of the organization and can observe non-verbal behavior, meaning data can be considered more reliable and valid

2. Unstructured interviews can reveal more questions that otherwise wouldn’t have been addressed, meaning more detailed reports.

1. Data from unstructured interviews is hard to summarize, evaluate, and analyze clearly

2. Level of detail depends on the type of interview - structured interviews can less detailed responses

3. Time-consuming to gather detailed results

Can be closed/restricted (box checking, yes/no form) or open/unrestricted (free-open questions)

Domain of applied statistics that focuses on taking samples from a population as well as improving on the carious data collection techniques

1. Time-saving and cost-efficient: can acquire information from a large group people easily and cheaply

2. Closed/restricted questions makes data easier to compare

3. Open questions means more detailed reported can be created

1. Level of detail depends on type of questions: closed questions don’t allow for clarifications or extra detail

2. Stakeholder could interpret the meaning of the question incorrectly and therefore invalidate their answere

On-site observation of different departments to see where things can be more different

1. Quick realistic information on procedures in the current system

2. Highlight aspects not detected in questionnaires/interviews, meaning more detailed reports can be introduced

3. May be more reliable than interviews, can see what stakeholders actually do, instead of what they report to do

4. Help to understand positive and negative features of the current system, which can be used when specifying the requirements of the new system

1. Time-consuming and expensive, an entire business or system cycle make be observed which could take significant time and administration costs

2. People act differently when they are being observed/scrutinized, making some observations unreliable

3. Observations may be made by only one person, and thus may be biased

Process that involves the detailed examination of the current system, analysis of its functions and procedures, studying the business and the system documents such as order documents, logistics documents, and computer systems procedures and reports used by operations and senior managers

The identification, retrieval and management of various sources in order to find information on a topic, areas that might be interesting for further studies, derive conclusions, as well as develop guidelines for practices

The analysis of competitive factors, their benefits, vulnerabilities, successful characteristics, the breakthroughs that they introduce, their design features as well as the users’ and stakeholders’ acceptance

1. Increase client trust

2. Preserve brand strength

3. Preserve organization reputation

4. Maintain corporate resiliency

5. Enhance organizational piece

A document that specifies system requirements. This document defines the specific customer requirements of a customer system. It is included within the system analysis and may be later used to test the system, after implementation, in order to evaluate it

• Online processing (interactive)

  • Data processing preformed by a single processor through the use of equipment that it controls.

• Real-time processing

  • Data processing performed on-the-fly in which the generated data influences the actual process taking place

• Batch Processing

  • Data processing performed on data that have been composed and processed as a single unit

The description of a data processing system, including the flow of data through any individual programs involved, but excluding the details of such programs. Constructed during analysis activities and represent various computer programs, files, databases, associated manual processes,etc

Action or Process

Input or Output Device

Document

Annotation

Lines Crossing

Lines Joining

Data Flow

Tape

Disk

Online Storage

Communication Link (Two Way unless Indicated)

Used to describe the problem to be solved. Shows how the data moves through a system and the data stores that the system uses. Does not specify the type of the data storage and the type of data.

Process. A operation performed on the date

Data Flow. Direction of data flow.

Data Store. File held on disk or a batch of documents.

External Entity

Describes functions and sub-functions of a system, as well as the relationships between modules of a computer program. The organization of a structure chart is straightforward, allowing the analyst to split a large problem into smaller ones.

The process of a designing system modules individually and then combining the modules to form a solution to an overall problem.

A software design and problem solving technique that involves the partition of a problem into smaller sub-problems

An artificial language that is not directly related to any particular hardware and is used to describe algorithms.

Complete and independent part of a program or an algorithm

Method of partitioning a computer program into separate sub-programs. The main advantage is that each sub-program can be easily modified and maintained without the necessity to alter other subprograms of the program

Language that supports modular programming

An early version or model of a system

• Attracts the attention of the client, since it encourages them to use it and “get a feel for it”

• Provides just enough of the concept for the investors to decide if they want to fund the full production or not

• Encourages active participation between users and developers

• Gives an idea of the final product

• Helps in the identification of problems with the efficiency or the desiItegn

• Increases system development speed.

The repetition of a set of instructions for a specific number of times or until the operations yield a desired results.

• With each iteration, additional features may be added until there is a fully functional software

1. Software not suitable for its intended use because of a lack of feedback

2. Adverse effects on user productivity, efficiency, and so on.

• Robots are replacing humans in many tasks, can be interpreted as just the job changing. Would create social disturbance similar to that during the Industrial Revolution

• Should this uncontrollable development continue?

• Continuous development of computerized systems may absorb people and cause them to drift apart from the physical world and become enclosed in virtual environments.

The potential of a service, product, device, or environment to serve and meet the needs of as many individuals as possible.

The potential of a product, application, or website to accomplish user goals

the design of safe and comfortable products, systems or process, specifically for people.

1. Complexity/Simplicity: Amount of effort to find a solution or get a result

2. Effectiveness: Comparison of user performance against a predefined level

3. Efficiency: Task completion time after the initial adjusting period

4. Error: Numbers of errors, type of errors and the time needed to recover from errors

5. Learnability: time used to accomplish tasks on the first use

6. Memorability: time, number of button clicks, pages, and steps used by users when they return to the device after a period of not using it

7. Readability/comprehensibility: Reading speed

8. Satisfaction: Attitude of users toward applications after using them; i.e. if users like it.

• Small Screen

• Low-quality speakers

• Antenna with poor performance that makes it difficult to receive a satellite signal

• Inaccurate geographical data

• Outdated street data

• Inefficient routing software

• Accidental touches leads to undsired selections

• Difficult to learn different gesture features of various manufacturers

• Bad or poor scaling and zoom control

• Difficult-to-use control features

• Small side buttons

• Poorly written instructions

• Some portable game consoles have relatively small screens

• Buttons may be too small

• Difficult to use outdoors (insufficient brightness)

• Short battery life

• Excessive keyboard use may lead to RSI (repetitive strain injury) syndrome

• Excessive use of a large, bright screen may cause eyesight problems or tire the eyes

• Poor room lighting conditions may lead to distracting reflections on the screen

• The mouse of a PC is a designed for right-handed people, making its use difficult for left-handed people.

• Incorrect calibration of touch screen menus

• The need to hold the camera vertically, does not allow convenient navigation through the touch-screens. An auto rotate screen option would increase usability

• If a camera does not have a flash capability or it is equipped with an inadequate flash then the user has to purchase and carry an extra hardware component

• The buttons are too small, making it difficult to push them

• Some cameras requires specific software to connect them with a computer and store or transfer files (no drag and drop files option)

• The keyboard of a mobile phone is very small and as a result many novice users elderly people or users with bad eyesight struggle to use it

• Some users don’t really need all the special feature; they just need a basic device for calls and SMS messaging

• Tiny buttons

• Insufficient memory

• Fragile

• Lack of a screen in “micro” or “shuffle” devices

• Overall usability can be improved by use of NLP (natural language processing) and making the overall interface more intuitive, so that even people not familiar with technology can use them

• Use of acceleration sensors or gesture control to enhance functionality

Input Devices/Methods

• Larger Screen;

• Braille input devices,

Output Devices/Methods

• Color or contrast changes

• Access to hotkey

• Functionality;

• Text-to-speech;

• Screen Magnification

• Speech Recognition

• Subtitles

• Visual Effects

• Voice Recognition

• Word processing to correct dyslexia

• Special software with strong interaction

• Use of touch screen and bright colors

Input methods/devices:

• Specialized disks

• Pointing device to press keys and control a personal computer

• Left-handed and right-handed keyboards

• Track balls and specialized input devices

• Expanded keyboards

• Scanning and Morse code

• Special Knobs

• Sip-and-Puff (SNP)

• Natural Language processing, voice recognition, and speech-recognition

• Word Prediction

Users will leave. If an interface is not appealing then it will not attract users.

They both refer to “right and wrong”. Religion, society, profession, and family set the ethic framework. One’s own principles set morals.