IB Computer Science: Topic 1 - System Fundamentals

Modular programming

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

SaaS (Software as a Service)

"On-demand software" is a contemporary (modern) delivery method that allows software and data to be hosted and managed centrally on a remote data center. Pros: Low initial cost, easy to upgrade, ease of access from anywhere, easy to predict the cost of initial implementation (subscription), the application is easy to use. Cons: dependence on a third party, security, and confidentiality, risk of data loss, not as powerful as on-premise solutions.

Parallel changeover

A Changeover where both systems work in parallel for a short period of time. If the new system fails, the company can revert or return to the old system, hence, it has limited risk. However, it requires extra costs and high workload.

Phased changeover

A changeover (conversion) method, where a company converts one module of the system at a time, meaning that different parts of the system are converted at different times. The training period is extended and the adoption of the new system takes longer, since each phase must be implemented separately (per module, per department, etc.).

Pilot changeover

A changeover method, where the new system is introduced in one of the sites and extended to other sites over time. This method has a low risk.

Module

A complete and independent part of a program or an algorithm.

dumb terminal

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

Interview

A direct face-to-face procedure that focuses on obtaining reliable and valid data in the form of verbal responses from a person or a group (stakeholder(s)). They can be structured (standardized and prescribed) or unstructured (flexible. Encouraging stakeholders to express their thoughts and personal beliefs freely). Cons: Time-consuming; data that is too difficult to summarize, evaluate or perform any form of statistical analysis on them.

requirement specification document

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

firewall

A hardware or/and software network infrastructure that controls data flow access among network entities. It offers protection and limits access to a network.

Direct (Big Bang / immediate) changeover

A highly risky changeover, where the company plugs in the new system and unplugs the old one at the same time. This method is used when the system is not critical.

router

A networking device that accepts incoming quanta of information (data packets), reads their destination address and distributes them across networks, according to a routing table or routing policy. It identifies the destination of messages and sends them via an appropriate route and is used to forward data packets between networks.

Modular design

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

Change Management

A process of shifting individuals, teams, departments, and organizations from the present state to the desired state.

Software

A series of instructions that can be understood by a CPU. These instructions guide the CPU to perform specific operations. It includes both programs and data.

Software incompatibility

A situation where different software entities/systems cannot operate satisfactorily, cooperatively or independently, on the same computer, or on different computers linked by a local or wide area computer network.

Top-down design

A software design and problem-solving technique that involves the partition of a problem into small subproblems. Each sub-problem is further broken down until all sub-problems are detailed enough and no more partitioning is required. Programmers are able to attack its sub-problem and develop the equivalent programming code.

client-server

A software network architecture system where clients request information and servers perform tasks in order to provide this information. Servers share their resources, whereas clients do not.

system flowchart

A system flowchart refers to the description of a data processing system, including the flow of data through any individual programs involved, but excluding the details of such programs. It represents various computer programs, files, databases, associated manual processes, etc. (page 35)

locally hosted system

A system that is the most appropriate solution for larger and complex systems.

remotely hosted system

A system that is the most appropriate solution where there is no necessary hardware equipment in place or in cases where administration wishes to outsource responsibilities for maintenance, support, backups, security, etc.

Debugging

A systematic process of finding and correcting a number of bugs (errors) in a computer program.

direct observation

A way of data collection that involves spending time in different departments, observing people. However, people tend to change their behavior when they know they are being observed. Observation without people's knowledge is unethical.

Questionnaire

An effective way of data collection when the questions are carefully constructed so as to elicit unambiguous responses. They can be closed/restricted (yes/no; short response questions; box checking) or open/unrestricted (involve free response questions).

Data loss

An error condition where data is lost or destroyed due to system failure, storage negligence, or even transmission or processing errors. Possible causes: accidental deletion; administrative errors; poor data storage organization system; building fires; closing the program without saving the file; computer viruses; continued use after signs of failure; data corruption; firmware corruption; natural disasters; thieves; physical damage of the storage device; power failure. Solutions: file recovery software; restructuring data organization; storing data in two locations; autosave features; antivirus software; regular backups; PC checkups; firewall; authentication methods; UPS; regular backups;

Peripheral device

Any auxiliary device that can communicate and work with a computer. For example, input/output devices, printers, etc. Such device extends the capabilities of the computer system it is connected to. It is not a core, essential, part of the computer.

failover system

Computer system that is on standby capable of switching to a spare computer system upon hardware failure, network failure, or any other type of error, such as software malfunction. Unlike switchover, a failover system is automatic and handles abnormal situations without human interference.

Domain Name System (DNS) server

DNS server attributes names to network addresses and therefore resolves names by assigning them to the appropriate network entity (a resource that is part of the network). It allows you to type names into the address bar of your web browser and the web automatically finds that address on the internet.

Data Flow Diagram (DFD)

Data Flow Diagram (DFD) is usually used to describe the problem to be solved (analysis). It shows how data moves through a system and then data stores that the system uses. It does not specify the type of data. page 37.

Extreme Data

Data outside the normal limits. These data should be rejected during validation testing.

Online processing

Data processing performed by a single processor through the use of equipment that it controls. For example, an airline reservation.

Batch processing

Data processing performed on data that have been composed and processed as a single unit. For example, payroll.

Real-time processing

Data processing performed on-the-fly in which the generated data influences the actual process taking place. For example, aircraft control.

Digital Citizenship

Digital Citizenship covers appropriate behavior in a digital world (using IT ethically, in a way that respects society, the law and does not expose any person to threats, danger, or contravention of their human right).

External documentation

Documentation, written as a separate document from the program itself. It's provided through various types of user supporting documents, such as a users' guide, software requirements specification document, detailed description of the design and implementation features of the program and test document.

Email support

Email support - Users contact the support team of the company to resolve any problems with the help of specialized technicians.

Embedded assistance (/integrated user assistance)

Embedded assistance or integrated user assistance - for example, when the use hovers the mouse over an icon and a small text box appears with valuable information.

Removable media

For example, Diskettes, Blu-rays, CDs, DVDs, USBs. They are used for fast data backup and data storage, They can store data permanently and are non-volatile (not liable to change unpredictably).

FAQ

Frequently Asked Questions

Globalization and Cultural Diversity

Globalization and Cultural Diversity - It helps diminish the importance of geographical, political, economic and cultural boundaries while speeding up the global spread of political, financial, sport and cultural news.

Ergonomics

Human engineering refers to the design of safe and comfortable products, systems or processes, specifically for people.

IT policies

IT policies are enforceable procedures and measures that promote the appropriate use of computers, networks, information systems, and technologies.

Intellectual property

Ideas, discoveries, scientific endeavors, photographs, films, essays, and artworks. Copyright laws are designed to protect intellectual property from unauthorized and illegal reproduction.

Redundancy

In computer science, it is the duplication of storage devices and stored data of a computer system with the intention of securing the stored data. It is considered as a failsafe method.

stakeholders

Individuals, teams, groups or organizations that have an interest in the realization of a project, or might be affected by the outcome of a project.

Server

It has saved data on it and offers it to clients. It may be a program or a computer that provides services requested by clients connected over a network.

Surveillance

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

Modular language

It is a language that supports modular programming.

thin client

It is a relatively low-performance terminal, which heavily, but not entirely, depends on the server to which it is connected to.

Pseudocode

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

prototype

It is either a working or non-working preliminary version of the final product or a simple version of the final system that is used as part of the design phase to demonstrate how the final product will work.

Privacy

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

email server

It is the equivalent of a post office that manages the flow of email in and out of the network, checks that an email address is valid, allows users to access their email, etc.

new system

It is usually created to replace a system that is inefficient, no longer suitable for its original purpose, redundant or out-dated. Also, to increase productivity/quality, minimize costs, reduce errors/flaws, etc...

Client

It receives data via a network. It is an average computer or terminal used to access a computer-based system.

Reliability

It 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.

Integrity

It 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.

Usability

It refers to the potential of a product, application or a website to accomplish user goals. It relates to effectiveness, efficiency, and satisfaction in a specified context of the use. Its components: Complexity/simplicity; effectiveness; efficiency; error; learnability; memorability; readability/comprehensibility; satisfaction.

Accessibility

It refers to the potential of a service, product, device or environment to serve and meet the needs of as many individuals as possible. Often it is studied in parallel with disabled people and special needs and the use of various assistive technologies. Critical aspects to consider: Visual impairment, from blindness to color vision deficiency (use braille keyboards); hearing and speech impairments; cognitive problems and learning disabilities (e.g. dysgraphia, dyslexia); Mobility impairments, limited hand mobility, Parkinson's disease;

Security

It 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.

Functional testing

It tests individual commands, text input, menu functions, etc. and confirms that they perform and function correctly according to the design specifications.

Manuals

Manuals - can be provided online or offline. Online manuals include the potential use of multimedia features, Printed manuals can be read without the use of a PC or an internet connection.

Online portals (or web portals)

Online portals (or web portals) - they are provided in many ways, such as updated manuals, support pages, and FAQ pages.

People and machines

People and machines - all aspects of the interaction between IT and humans.

Human resources

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

Inconsistency

Problems may also arise if the information is duplicated in a database and only one copy is updated, causing inconsistency.

Remote desktop connections

Remote desktop connections - remote desktop enables a specialized person to connect to the user's PC across the internet from virtually any computer. It is ideal when the user is not very experienced, however, the solution has some security disadvantages.

Standards and Protocols

Standards and Protocols are predefined technical rules and conventions that developers of hardware and software should follow. They ensure different systems are compatible with each other.

structure chart

Structure chart - describes the functions and sub-functions of a system, as well as the relationships between modules of a computer program.

Unit testing

Testing of individual parts of the system separately.

Dry-run testing

Testing that is conducted using pen-and-paper by the programmer. Here, a programmer mentally runs the algorithm.

Alpha testing

Testing that is done before the software product is made available to the general public. Mainly, carried out by the company that develops the software in a laboratory type environment and not by end users in their usual workplaces.

User acceptance testing

Testing used to determine if the system satisfies the customer needs and in most cases is conducted in user premises before accepting to transfer of ownership. This is the last stage of the software testing process.

Beta testing

Testing where users outside the company are involved in the testing. Their feedback is valuable and can be used to fix defects and errors that were missed, and also contributes to the preparation of support teams that will deal with expected issues.

Integration testing

Testing, during which, the entire system is tested at the same time to verify that all components can work together.

The Digital Divide and Equality of Access

The Digital Divide and Equality of Access - Economic costs, financial costs, lack of literacy, lack of language skills (English) and lack of basic resources such as electricity are the main reasons that sustain the digital divide.

Internal documentation

The code comprehension features and details provided as a part of the source code itself.

End-user

The person who is going to use the product.

Computer hardware

The physical elements of a computer, e.g. screen, CPU, etc.

Verification

The process of ensuring that the data input is the same as the original source data. A way of ensuring data verification is through the double entry. Are we developing the system correctly? Does the product comply with specific regulations or condition?

Validation

The process of evaluating whether data input follows appropriate specifications and is within reasonable limits. Are we developing the correct system? Does the product meet the customer needs?

Changeover (conversion, implementation)

The process of putting the new systems online and retiring the old one.

iteration

The repetition of a set of instructions for a specific number of times or until the operations yield the desired result. Initially, all design systems, interfaces or softwares have functional or usability problems. Iterative development of software involves steady improvement of the design based on various evaluation and testing methods.

System Life Cycle

The stages through which the development of a new system passes through. Generally, these include Analysis, Design, Implementation, Operation, Maintenance.

Date migration

The transfer of data between different formats, storage types and computer systems. Its stages: Plan >> Migrate >> Validate.

Abnormal (illegal) Data

The type of data that we really didn't expect. For example, inputting a string data instead of integer data.

Upgrades

They always contain novel functionalities or characteristics, as well as cumulative bug fixes. In most cases, they need to be bought.

Releases

They are final, working versions of software applications. These applications have already gone through testing. They relate to new or upgraded applications.

Patches

They are used by software companies to update applications by fixing known bugs and vulnerabilities. Be aware that, patches may introduce new bugs as a side effect.

Updates

They improve a product in a minor way by adding new functionalities or fixing known bugs. In most cases they are free.

Feasibility report

This study evaluates and analyses a project and its potential, based on various technical, economic, legal, operational and scheduling criteria. It is used to decide whether the proposed project should be pursued. (TELOS)

User training

User training - can be delivered in a number of different ways, depending on a variety of factors, such as the number of the students, the availability of instructors, the size of the business, and the training budget. Examples include: Self-instruction/Self-study (using printed manuals, books, e-books, video tutorials, online exercises and so on.); formal classes; remote/distance learning / online training;

Anonymity

When an individual uses an IT system to conceal his/her true identity in order to cyber-bully another person, commit illegal actions or crimes, hack computers, commit terrorism, etc.

Data testing

When normal, abnormal and extreme data is put into the system

computer system

a computer system includes hardware, software, people working with it or using it and the immediate environment.

Live chat sessions

live chat sessions - online support, real-time support, that is extremely useful for emergency situations.

Impairment

loss or abnormality of a psychological, physiological, or anatomical structure or function.

Business merger

the combining of two or more business entities into a single corporation. Mainly, to reduce costs. In the process, both companies need to ensure that all subsystems are compatible.

Planning

the process of thinking about various details and organizing the activities required to achieve the desired goal.

Legacy system

the term refers to old technology, hardware, computer system, or application program. Such a system may still be in use because its data cannot be converted to newer formats, or its applications cannot be upgraded.