Operating Systems and Computer Applications, Exams of Advanced Education

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INFX 101 Test 2 Study Guide questions and answers

What does an operating system do? - >>To ease application programming, an operating system (or OS) is itself a program that implements the detailed interactions with hardware (among other things), presenting an application program with a more abstract interface (it interacts with an application and its hardware) What is a multitasking OS? - >>it supports running multiple applications seemingly simultaneously. To a user, multiple applications like a music player and a web browser appear to be running simultaneously, but in fact the OS is running a little bit of each application at a time, switching thousands of times per second. (It shares time, gives slots out based on the operating system or application) What is a graphical user interface? - >>Early operating systems were text-based. Users would type commands. Operating systems evolved to have simple graphical interfaces, including a mouse for pointing and clicking. The graphical interfaces improved dramatically, including rich colors, images, and functionality. Recent operating systems abandon keyboards and mice and instead have users do work by touching the screen and by using various multi-finger gestures. What are text-based operating systems (command-line)? - >>it requires typing to view, copy, move, or delete files or folders, or to run programs- handles text and not graphics What was MS DOS - >>an original command-line text-based OS. Was introduced in 1981 by Microsoft as a relatively simple OS for PCs, which were new at that time. (t/f) iphones and tablets have an OS - >>true What is a folder? - >>A user may wish to organize files using folders. A folder is a grouping of files or other folders, that helps a user organize items. A role of an OS is to manage files and folders, keeping track of such items' locations on a drive, making such items visible to a user, and allowing a user to open files or run apps.

When it comes to handling files the OS sees where we place them in ___________. - >>storage What happens when you delete a file? - >>Moving files to the trash or recycle bin does not actually delete files from the drive. Deleting does not remove from storage but frees up that space. A user must empty the trash to delete files from the drive. What is a memory leak? - >>The longer the app runs, the more memory the app uses, even though the app doesn't really need the additional memory. Memory leaks are caused by certain bugs in the app, but apps aren't perfect so leaks are common. Leaks are especially noticeable in web browsers, which tend to be left running without quitting for long periods. Thus, a user may find that quitting and restarting an app, perhaps every few days, results in less memory usage and thus faster-running apps. What is LZ compression? - >>An LZ compression algorithm examines data for long repeating patterns such as phrases, and creates a dictionary entry for such patterns. What is lossless compression? - >>It loses no information, so that decompression yields an identical file to the original. LZ and Huffman approaches are lossless. What is a lossy compression? - >>It loses some information, so the decompressed file is close but not identical to the original. Huffman encoding - >>it measures the frequency of each data item like each letter, and gives the most frequent items a shorter bit encoding (like the letters "a" and "e"), with least frequent items getting a longer encoding (like letters "q" and "z"). What is a word processor? - >>a common computer application for creating formatted text How are spreadsheet cells organized? - >>into columns labeled A, B, ... and rows labeled 1, 2, ...; a spreadsheet user can type data in each cell.

What are spreadsheet function? - >>built-in operations that simplify calculations; Functions take a single cell or a range of cells as input. A function is entered into a cell, which will then display the value determined by the function. What is a formula in a spreadsheet? - >>An important spreadsheet feature allows a user to type a formula in a cell to compute that cell's value based on other cells' values. The formula begins with = followed by a math expression using operators like +, -, *, /, and parentheses (). What is a cell in a spreadsheet? - >>A spreadsheet contains cells organized into columns labeled A, B, ... and rows labeled 1, 2, ...; a spreadsheet user can type data in each cell. What is a presentation app? - >>a computer application used to create a slideshow of text and graphics, often with animation What is a primary key in a database? - >>A record's unique identifier (each record contains one) What is stored in a field (column) in a relational database? - >>Basic unit of data stored What is stored in a record (row) in a relational database? - >>A group of related fields What is a table in a relational database? - >>collection of related data Audio formatting (from microphone to recording app) - >>A microphone converts vibrating air into an analog electrical voltage on a wire. An audio recording app may then rapidly "sample" that voltage using hardware called an analog-to-digital converter to convert each sample to a number, and storing the numbers in a file. What is a frame? - >>each image in a video is a frame

What makes a video seem smoother? - >>more frames per second (fps) What is social networking? What is the most widely used social networking site? - >>A social networking site connects people, via common interests, backgrounds, real-life connections, etc. Facebook is the most widely used site What is a wiki? - >>a website that enables collaborative development of content. What is crowdsourcing? - >>an approach to developing content that involves having the users (the "crowd") be the contributors, rather than using highly-paid professionals. Describe the importance of device drivers - >>The OS portions that interface with hardware. It is software that interfaces with a hardware device like a screen, keyboard, or printer. A device driver prevents application developers from having to create applications that interface directly with hardware.