1.2 - System Design Basics Flashcards
What are the components of a computer system?
Computer hardware: the physical elements of a computer (screen, CPU..)
Software: a series of instructions that can be understood by a CPU, which guide the CPU to perform specific operations. Software is comprised of both programs and data.
Peripheral device: any auxiliary device that can communicate and work with a computer. It extends the capabilities of the computer system it is connected to. The peripheral device isn’t a core, essential part of the computer (printer, keyboards…)
Computer network: a set of computer systems that are interconnected and share resources and data (LAN, WAN…)
Human resources: people who are or can be used in an organization, business or economy.
Dumb terminal
A device that usually consists of a keyboard, 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.
Thin client
A thin client is a relatively low performance terminal, which heavily but not entirely, depends on the server to which it is connected.
Client and Server
A client receives data via the network, whereas the server has saved data on it and offers it to clients. A server may be a program or a computer that provides services requested by
clients connected over a network while a client is an average computer or terminal (dumb terminal, thin client) used to access a computer-based system.
Email server
An email server 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.
Router
A router is 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 (policy based routing). A router identifies the destination of messages and sends them via an appropriate route and is used to forward data packets between networks.
Domain Name System Server
A Domain Name System Server attributes names to a network addresses and therefore resolves names by assigning them to the appropriate network entity. It is protocol within the set of the TCP/IP protocol suite and is used for managing public names of web sites. One can always bypass a DNS lookup by entering the internet protocol (IP) address directly into a browser. (Search)
Firewall
A firewall is a hardware or software network infrastructure that controls data flow access among network entities. Mainly used to offer protection and limit access to a network. Ideal firewall system consists of hardware and software components.
Client-server
A client-server refers to a 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.
The IT subjects of social and ethical significance
Reliability - 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 - protecting the completeness and accuracy of data. Data lacks integrity if it is incomplete, out of date, or has been purposely or
unintentionally altered.
Inconsistency - Problems may also arise if information is duplicated in a database and only one copy is updated, causing inconsistency (e.g. telephone field).
Security - 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. Authenticity, which 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.
Privacy - 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 has access to the data and how the data is used.
Anonymity - Privacy becomes
anonymity when, for instance, an individual uses an IT system to conceal
his/her true identity in order to commit illegal actions or crimes.
Intellectual property - Copyright laws are designed to protect intellectual property from unauthorized and illegal reproduction.
The Digital Divide and Equality of Access - 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.
Surveillance -using IT to monitor individuals or groups of people
either with or without their knowledge or permission.
Globalization and Cultural Diversity - IT helps to diminish the importance of
geographical, political, economic and cultural boundaries while speeding up the global spread of political, financial, sport and cultural news. Traditional cultures and values may diminish gradually over time.
IT Policies - Policies are enforceable procedures and measures that promote the
appropriate use of computers, networks, information systems and technologies.
Standards and Protocols, which are predefined technical rules and conventions that developers of hardware and software should follow. Standards and protocols allow for compatibility, facilitate communication and interoperability.
People and machines - 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.
Digital Citizenship - appropriate behavior in a digital world. Appropriate
behavior includes using IT ethically, in a way that respects society, the law and does not expose any person to threats, danger, or a contravention of their human rights.
What are 3 types of processing?
Online processing (interactive) - data processing performed by a single processor though the use of equipment that it controls (airline reservation)
Real-time processing - data processing performed on-the-fly in which the generated data influences the actual process taking place (aircraft control)
Batch processing - data processing performed on data that have been composed and processed as a single unit (payroll)
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. System flowcharts are frequently constructed during analysis activities and represent various computer programs, files, databases, associated manual processes, etc.
Data Flow Diagrams (DFD)
A DFD may usually be used to describe the problem to be solved (analysis). A DFD shows how data moves through a system and the data stores that the system uses. A DFD does not specify the type of the data storage and the type of data.
Structure charts and Modular design
A structure chart 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.
Modular design is the process of designing system modules individually and then combining the modules to form a solution to an overall problem
Pseudocode
Pseudocode is an artificial language that is not directly related to any particular hardware and is used to describe algorithms. Pseudocode does not follow the grammar of any specific computer language and requires conversion to a computer language before the resulting program can be used.
