Untitled Flashcards Set

Here are some flashcards based on the information in the sources you provided:

Operating Systems

Front: What is an operating system?

Back: An operating system is system software that allows a user to interact with a computer and makes the parts of a computer system work together.

Front: What are the roles of an operating system?

Back: An operating system:

• Facilitates practical use of a computer system and its resources

• Manages numerous, concurrently running programs (process management)

• Allocates and tracks memory efficiently (memory management)

• Grants and shares access to computer hardware (device management)

Front: What is process management?

Back: Process management is the act of managing the use of the CPU by individual processes. A process is a program in execution.

Front: What are the different states a process can go through?

Back:

• New: The OS copies program code into RAM.

• Ready: The process is ready to be executed by the CPU. There may be other processes running.

• Running: The CPU is executing the instructions of the process.

• Waiting: The process is waiting for an event, such as network data, a timer event, a keypress, or a screen touch.

• Terminated: The process has finished executing and its memory and other resources are freed.

Front: What is CPU scheduling?

Back: CPU scheduling is the act of determining which process in the ready state should be moved to the running state. Only one process can be in the running state at any one time, even if multiple processes are in the ready state.

Front: What are the two types of CPU scheduling?

Back: The two types of CPU scheduling are:

• Non-preemptive scheduling: The currently executing process gives up the CPU voluntarily.

• Preemptive scheduling: The operating system decides to favour another process, preempting the currently executing process.

Front: What is turn-around time?

Back: Turn-around time is the amount of time between when a process arrives in the ready state the first time and when it exits the running state for the last time.

Front: What are some CPU scheduling algorithms?

Back: Some CPU scheduling algorithms are:

• First-Come, First-Served (FCFS): Processes are moved to the CPU in the order in which they arrive in the ready state.

• Shortest Job Next (SJN): The process with the shortest estimated running time in the ready state is moved into the running state first.

• Round Robin: Each process runs for a specified time slice and moves from the running state to the ready state to await its next turn if not finished.

Front: What is a weakness of FCFS?

Back: A weakness of FCFS scheduling is that if a process hangs, subsequent processes will never run.

Front: What is a benefit and a weakness of SJN?

Back: Benefit: SJN is a provably optimal strategy for average turn-around time. Weakness: SJN relies on knowledge of the future (how long a process will take).

The World Wide Web

Front: What is the World Wide Web (WWW)?

Back: The WWW is a way of accessing information on the Internet. Information is encapsulated in a webpage and viewed in a web browser. Webpages are linked to one another via hypertext links. Clicking on a link accesses the associated webpage or resource.

Front: What is the difference between the WWW and the Internet?

Back: The Internet is the infrastructure while the WWW is one of the services on the Internet.

Front: What is the Client-Server Model?

Back: The Client-Server Model describes the interaction of networked computers.

• Clients request information from servers.

• Servers respond with the information (if applicable).

• Any computer can act as a client or server.

• Computers are typically described as "client" or "server" based on their role the majority of the time.

Front: What is HTTP?

Back: HyperText Transfer Protocol (HTTP) is:

• a method of requesting and transmitting web pages.

• used for communication between client computers and web servers by sending HTTP requests and receiving HTTP responses.

• used when a user clicks on a link or enters a URL in a browser: a request is sent to the HTTP port (80 or 8080) of the associated web server.

• used by the server to respond to the client's request.

Front: What are some examples of web browsers?

Back: Some examples of web browsers are:

• WorldWideWeb (the first web browser)

• Mosaic

• Netscape Navigator

• Internet Explorer

• Firefox

• Safari

• Google Chrome

• Edge

Front: What are search engines?

Back: Search engines are systems that search the web and catalogue (index) the content of web pages.

• Users provide search criteria, and the search engine presents a collection of web content that satisfies some or all of the criteria.

• Search criteria can be text and can be combined with Boolean operators to improve specificity.

• Search results can sometimes be filtered based on geographic origin, time frame, and content type.

Front: What are some examples of search engines?

Back: Some examples of search engines are:

• Google

• Bing

• Yahoo

Front: What is HTML?

Back: HyperText Markup Language (HTML):

• defines the content of a webpage as a text file with a .html extension.

• uses tags to specify content characteristics.

  • Tags appear as text in < > (e.g., indicating document body).

  • Some tags appear as a pair of open-close tags.

  • Closing tag is </ > (e.g., …).

  • A tag may specify additional attributes.

• links to other content (e.g., images) using the appropriate tag.

• can be used to create a web of interconnected content by linking webpages.

Front: What is WYSIWYG?

Back: WYSIWYG ("wiz-ee-wig") stands for "What You See Is What You Get" and:

• refers to any kind of editing software where the content in the editor resembles its final form.

• HTML, when edited in a standard text editor, is NOT WYSIWYG. (Though WYSIWYG editors for HTML do exist).

Front: What are some examples of WYSIWYG software?

Back: Some examples of WYSIWYG software include:

• Most text editors

• Microsoft Word

• Microsoft PowerPoint

• Microsoft Excel

• Gimp

• Audacity

Front: What is the basic structure of a webpage?

Back: A simple webpage is a text file with a .html extension and has the following structure:

• <html>…</html> outline the HTML document.

• <head>…</head> contain information about the document (e.g., author, keywords).

• <body>…</body> contain the main content of the webpage.

• Spacing and indentation within the HTML file typically do not affect correctness or appearance but are done to aid in human readability.

Front: What are some HTML tags?

Back: Some HTML tags include:

• <p>…</p>: text treated as a separate paragraph.

• <br>: forced line break.

• <hr>: horizontal rule across the page.

• <ul>…</ul>: unordered list (usually bullets).

• <ol>…</ol>: ordered list (e.g., numbered).

• <li>…</li>: list item.

• <h1>…</h1>: level 1 heading (also h2, h3,… h6).

• <div>…</div>: division (area) with special characteristics.

• <img>: displays an image file.

• <a>…</a>: hypertext link anchor.

• <!-- … -->: comments within the HTML code.

Front: How do tag attributes work?

Back: Tag attributes provide additional characteristics for a tag.

• Syntax: attrName="value".

• Example: <div align="center">…</div> centres the content between the tags.

• Example: <img src="../smile.png" width="300" height="200"> displays the image indicated by src, restricting it to 300 pixels wide by 200 pixels high.

• Example: <a href="http://www.yorku.ca">York University</a> displays "York University" as a hyperlink to www.yorku.ca.

Front: What are Cascading Style Sheets (CSS)?

Back: CSS:

• describes how HTML elements are to be displayed on screen, paper, or in other media.

• defines the styles of text and other classes of content (e.g., background, images, etc).

• can control the layout of multiple web pages at once.

• can be added to HTML elements in 3 ways:

  • Inline: using the style attribute in HTML elements.

  • Internal: using a <style> element in the <head> section.

  • External: using an external CSS file.

• The most common way to add CSS is to keep the styles in separate CSS files.

Front: What does inline CSS do?

Back: Inline CSS is used to apply a unique style to a single HTML element, using the style attribute of an HTML element.

Front: What does internal CSS do?

Back: Internal CSS is used to define a style for a single HTML page within a <style> element in the <head> section.

Front: Where can I learn more about CSS?

Back: More information about CSS is available at:

• https://www.w3schools.com/css/css_intro.asp