A computer is a device that can be instructed to carry out an arbitrary set of arithmetic or logical operations automatically. The ability of computers to follow a sequence of operations, called a program, make computers very applicable to a wide range of tasks. Such computers are used as control systems for a very wide variety of industrial and consumer devices. This includes simple special purpose devices like microwave ovens and remote controls, factory devices such as industrial robots and computer assisted design, but also in general purpose devices like personal computers and mobile devices such as smartphones. The Internet is run on computers and it connects millions of other computers.

This article presents a list of commands used by DOS operating systems, especially as used on x86-based IBM PC compatibles (PCs). Other DOS operating systems are not part of the scope of this list.

In DOS, many standard system commands were provided for common tasks such as listing files on a disk or moving files. Some commands were built into the command interpreter, others existed as external commands on disk. Over the several generations of DOS, commands were added for the additional functions of the operating system. In the current Microsoft Windows operating system, a text-mode command prompt window, cmd.exe, can still be used.

Microsoft Windows (or simply Windows) is a metafamily of graphical operating systems developed, marketed, and sold by Microsoft. It consists of several families of operating systems, each of which cater to a certain sector of the computing industry with the OS typically associated with IBM PC compatible architecture. Active Windows families include Windows NT and Windows Embedded; these may encompass subfamilies, e.g. Windows Embedded Compact (Windows CE) or Windows Server. Defunct Windows families include Windows 9x, Windows Mobile and Windows Phone.

Microsoft Office is an office suite of applications, servers, and services developed by Microsoft. It was first announced by Bill Gates on 1 August 1988, at COMDEX in Las Vegas. Initially a marketing term for a bundled set of applications, the first version of Office contained Microsoft Word, Microsoft Excel, and Microsoft PowerPoint. Over the years, Office applications have grown substantially closer with shared features such as a common spell checker, OLE data integration and Visual Basic for Applications scripting language. Microsoft also positions Office as a development platform for line-of-business software under the Office Business Applications brand. On 10 July 2012, Softpedia reported that Office is used by over a billion people worldwide.

PageMaker was one of the first desktop publishing programs, introduced in 1985 by Aldus, initially for the Apple Macintosh and, in 1987, for PCs running Windows 1.0. As an application relying on a graphical user interface, PageMaker helped to popularize the Macintosh platform and the Windows environment. PageMaker relies on Adobe Systems' PostScript page description language. In 1994, Adobe Systems acquired Aldus and PageMaker.

Aldus Pagemaker 1.0 was released in July 1985 for the Macintosh and in December 1986 for the IBM PC. Aldus Pagemaker 1.2 for Macintosh was released in 1986 and added support for PostScript fonts built into LaserWriter Plus or downloaded to the memory of other output devices. PageMaker was awarded an SPA Excellence in Software Award for Best New Use of a Computer in 1986. In October 1986, a version of Pagemaker was made available for Hewlett-Packard's HP Vectra computers. In 1987, Pagemaker was available on Digital Equipment's VAXstation computers. Aldus Pagemaker 2 was released in 1987. Until May 1987, the initial Windows release was bundled with a full version of Windows 1.0.3; after that date, a "Windows-runtime" with no task-switching capabilities was included. Thus, users who did not have Windows could run the application from MS-DOS.

CorelDraw (styled CorelDRAW) is a vector graphics editor developed and marketed by Corel Corporation. It is also the name of Corel's Graphics Suite, which bundles CorelDraw with bitmap-image editor Corel Photo-Paint as well as other graphics-related programs (see below). The latest version is designated X8 (equivalent to version 18), and was released in March 2016. CorelDraw is designed to edit two-dimensional images such as logos and posters.

In 1987, Corel hired software engineers Michel Bouillon and Pat Beirne to develop a vector-based illustration program to bundle with their desktop publishing systems. That program, CorelDraw, was initially released in 1989. CorelDraw 1.x and 2.x ran under Windows 2.x and 3.0. CorelDraw 3.0 came into its own with Microsoft's release of Windows 3.1. The inclusion of TrueType in Windows 3.1 transformed CorelDraw into a serious illustration program capable of using system-installed outline fonts without requiring third-party software such as Adobe Type Manager; paired with a photo-editing program (Corel Photo-Paint), a font manager and several other pieces of software, it was also part of the first all-in-one graphics suite.

Photoshop was created in 1988 by Thomas and John Knoll. Since then, it has become the de facto industry standard in raster graphics editing, such that the word "photoshop" has become a verb as in "to Photoshop an image," "photoshopping" and "photoshop contest", though Adobe discourages such use. It can edit and compose raster images in multiple layers and supports masks, alpha compositing and several color models including RGB, CMYK, CIELAB, spot color and duotone. Photoshop has vast support for graphic file formats but also uses its own PSD and PSB file formats which support all the aforementioned features. In addition to raster graphics, it has limited abilities to edit or render text, vector graphics (especially through clipping path), 3D graphics and video. Photoshop's featureset can be expanded by Photoshop plug-ins, programs developed and distributed independently of Photoshop that can run inside it and offer new or enhanced features.

In this Photoshop tutorial, we'll learn how layer blend modes make it easy to add a popular lens flare effect to a photo without making any permanent changes to our image. We'll start by adding the lens flare normally to position it exactly where we want it, then we'll undo the effect, add a new layer, re-apply the lens flare instantly using a handy keyboard shortcut, and finally, we'll blend the lens flare into the image using one of Photoshop's most common and widely used blend modes.

In this Photoshop tutorial, we'll learn how to add lomo color effects to a photograph using Photoshop. In this tutorial we only use the bulit in plugins in Photoshop CS or later editions.

CPU is the brain of any computer. It controls all activities inside the computer. Basically it performs 2 types of operations - arithmetic & logical operation (internally), operations are performed on 2 types of devices - I/O and memory devices. It uses the "address bus" to select any "location" on these devices, sends a read/write signal over the "control bus" and then the information over the "data bus".

Memory Devices : The CPU stores all information in the computer's memory. There are two memory types - RAM & ROM

ROM (Read only memory): ROM can be programmed using a programmer and then it acts as a "read only" device. This device is used as the textbook for the CPU in the computer and is called ROM BIOS. It stores all the basic information of programming the devices present inside the system as well as the POST (Power On Self Test) sequence. AMIBIOS and AWARD BIOS are the most common ROM BIOS.

In my free time, I really like surfing the Internet. When I get home from work, I turn on my computer, wait until it boots up completely, and then I go online. I still have a dial-up connection, but I'm switching to a broadband Internet service soon. It costs more a month, but Webpages load faster with a high-speed connnection, and I can upload and download files quicker. I usually check my email first and write a few messages first to family and friends. I sometimes scan the local news headlines at my favorite news Website and read up on the latest local and international news. This Website often provides video news clips that you can view online. I sometimes order products or service online to save money and time instead of going to a store and buying what I'm looking for. For example, I ordered a digital camera online the other day and saved about $50. Whatever I do, I realize that there are problems with using the Internet including scams, identify theft, and viruses, so I'm very careful not to give out my personal information. Furthermore, I don't download or open files I don't recognize. Using the Internet can be fun and convenient way of shopping and finding out new information, but you just need to be careful.