Intro to IT

File compression involves reducing the number of bits and bytes in a file so that a file can be transferred over the internet at a faster rate. Compressed files will also take up lesser space when stored in a disk. Compressed files are then "decompressed" using specific programs after they are downloaded completely in the computer. Such programs are WinZip or Stuffit.

A head crash is a serious malfunction involving the disk drive. This malfunction occurs when the read/write head (separated from the disk drive by a layer of air as thin as 0.000001 inches) touches the surface of the hard disk and scratches it. This will result in the loss of  most data stored in the disk drive. A head crash may also occur when tiny particles like dust or smoke touch the surface of the disk drive.

Internet hard drives are available at specific sites on the web. Storing data on internet hard drives are similar with storing data on the  usual hard drive. The only difference is that data stored on Internet hard drives can only be accessed when a connection to the Internet is available. Among the advantages of Internet hard drives is that it can offer almost unlimited space with no cost at all. Furthermore, a user does not have to worry about data being lost as the data will remain on internet hard drives even if a computer's hard drive crashes. Among the disadvantages is that accessing internet hard drives might take a longer time.

Optical Disk Drive

An optical disk drive is the component in the computer that is involved in retrieving data from optical disks as well as storing data on optical disks The surface of any optical disks contain reflective and non-reflective surfaces representing a binary of 1 and 0 respectively. The optical disk drive uses a laser that projects a tiny beam of light on these surfaces. The disk drive interprets the amount of light reflected by the surface and convert them into digital data which can be read and understood by the computer.

Solid state storage devices unlike hard disks, have no moving parts. Although purchasing these devices with an equivalent amount of memory on a hard disk is much more costly, they are more reliable, portable, require less power and less easy to be damaged. The two main types of solid state storage would be USB drives and flash memory cards. In today's world, USB drives have replaced the tradition floppy disk mainly because they are more compact and have more memory capacity. The capacity can range from 1GB to 64GB. Flash memory cards are usually used in devices such as digital cameras, digital video recorders and even mobile phones. Solid state storage devices can be easily accessed through the computer to save or transfer files.

Ergonomic keyboards are designed to reduce muscle strains of the wrists and fingers that are caused by repetitive movements while typing. The key are usually separated into two groups allowing the user to type at a more comfortable angle compared to the traditional keyboard. There are two types of ergonomic keyboards which are the fix-split key board and the adjustable split keyboard. The adjustable split keyboard consist of several pieces  which angles can be change according to the user's preference. Although usage is more comfortable, buying an ergonomic keyboard may be more costly.

An inkjet printer prints images by spraying extremely tiny dots of ink (with a diameter between 50 to 60 microns) at very high speeds. Colour printing is available in inkjet printers. They are one of the popular types of printers being used today as it is reliable, does not produce much noise and not too expensive. However, what may be costly about having an inkjet printer is the replacement of its ink cartridges. 

Using a similar technology used in photocopying machines, laser printers can produce images with high letter and graphics quality. The images are produced by using a laser light beam (as suggested by its name). Compared to inkjet printers, laser printers produce better quality black text documents and printing does not cost as much. There are two categories for laser printers; personal laser printers which are less expensive but do not support colour and shared laser printers which support colour but is more expensive.

Magnetic ink character recognition is a system which uses ink that can be magnetised and read by a computer. This system by mainly used in banks in processing cheques (the digits and characters at the bottom of cheques). The advantage about this system is that the characters can still be read even if it is obscured by other marks or overprinted.

The OCR system uses an optical scanner to read preprinted characters. The data read by the optical scanner is transferred to the computer and a software analyses the characters and converts them into a form that the computer can understand (ASCII codes). This system is widely used today in retail shops, supermarkets and even in libraries. Items can be easily found and traced using the OCR system as all the information is stored in the software.

OMR systems are usually used in checking survey forms or examination documents such as the multiple-choice sheet. The system recognize human marked data by using a scanner that shines a beam of light. The scanner differentiates the reflectivity of bright and shaded areas  and interprets it into a form that the computer can understand. This is a very efficient way of checking documents as the OMR system is able to do it quickly without any errors.

Flash memory has a combination of RAM and ROM. It can be updated to store new information and it does not lose information when the power supply of the computer system is turned off. Among its uses are storing the start up instructions for a computer (information like the amount of RAM, type of keyboard and mouse, etc.)

Graphic cards connect the system board to the computer's monitor. They convert internal electronice signals to video signals which enable them to appear on the monitor.  The system unit, working in conjunction with application softwares, sends information about the image to the graphics card. The graphics card decides how to use pixels to create the image. It then sends that information to the monitor. ­

Sound cards take in any audio input from a microphone and converts it into a form that computers can process. These cards also do the opposite by converting internal electronic signals to audio signals so that they can be heard by the speakers. This is done by translating analog and digital signals. In the case of voice recording  through a microphone, the sound card translates the analog waves and digitizes the sound by taking precise measurements of the wave at frequent intervals. 

The NIC forms a communication network by connecting two or more computers together. Users can then share data, programs and hardware.  Networked computers communicate with each other using a given protocol or language for transmitting data packets between the different machines, known as nodes.

Plug and play is the ability of a device  to be plugged into a computer and to work or be played immediately. Back the, an operating system had to be "informed" that a new device has been plugged into the computer. Developed by Microsoft,  the plug and play function was for its Windows 95. Devices which are not plug and play devices require a driver to be installed in order to enable usage.

A bus line connects to parts of the CPU to each other. They link the CPU to other components on a system board. The busline is a pathway for bits that represent data and instructions. A bus width is the number of bits that can travel at the same time down a bus line. The speed and power of a computer is affected very much by the bus line design or architecture. Bus lines can be divided into two categories which are system bus lines and expansion bus lines. System bus lines are the ones which connects teh CPU to memory. Expansion bus lines on the other hand connect teh CPU to components on the system board.

HDMI is an interface standard used for audiovisual equipment. Before HDMI, computers use component video, S-video and composite video. The interface used was analog.With an analog interface, a clean digital source is translated into less precise analog. At each translation, the digital signal loses integrity, resulting in some distortion. HDMI however, preserves the source's signal as its signal is all digital. The results are visuals and audio of high quality.

A cache memory acts as a high-speed holding area between the memory and the system unit. A computer detects the most frequently used information in the RAM and copies that information into the cache. The system unit can then access the information quickly whenever it is needed. Cache memory optimizes performance and saves time.

Audio editing softwares allow a user to create and edit audio files. With such a software. users are allowed to add audio effects to tracks, filter out pops or scratching in an old recording and also to create MP3s. Two examples of often used audio editing softwares today are Apple's GarageBand and Sony's ACID.

Also known as raster images, bitmap images consist of thousands of pixels to form images. Each dot has a specific location and color. One downside of bitmap images is that when they zoomed in or expanded, the images appear to be pixilated. (Image appears to be jagged on the edges.

Instead of using  pixels, a vector image uses geometric shapes or objects created by connecting lines and curves. These objects can be easily resized and manipulated as they can be defined by mathematical equations. With this, vector images don not appear pixilated like bitmap images when magnified. 

Desktop Publishing Programs allow end-users to create publications by mixing texts and graphics. A desktop publisher focuses on page design and layout. Such programs are used by graphic artists to create documents such as brochures and newsletters. Examples of commonly used desktop publishing programs are Adobe PageMaker and Microsoft Publisher.

An HTML editor is an application software used for creating web pages. It is a program that provides support for web site design and HTML coding. Three types of editors are text editors, object editors and WYSIWYG (What You See Is What You Get) editors. WYSIWYG editors preview pages described by HTML codes. Commonly used programs include Adobe Dreamweaver and Microsoft Expression.

Image editors are used to edit or modify digital images (usually bitmap images). These programs contain a variety of tools that allow the user to modify a particular image to his preferences. Microsoft Paint or Adobe Photoshop are examples of image editors.

Multimedia integrates several forms of media (video, music, voice) into one presentation. However, the documents produced only provide limited user interaction. Multimedia presentations usually contain links and buttons for interactivity. Creating multimedia presentation are not that simple and there are several steps that need to be followed such as planning and analyzing, designing and creating.

A GUI is an interface consisting mainly of windows, icons, menus, and a pointer which can be manipulated using a mouse. A  GUI makes a computer simple and easy to use. They also enable end-users to multi-task as GUIs make it possible for multiple programs to run at the same time.

Word Processors are used to create text-based documents. It is a program which consists of many features that enables a user to edit and modify documents as they wish. With a word processor, an end-user is able to have their spelling and grammar mistakes checked, their documents formatted and their font's style and size changed accordig to preference. Examples of Word Processors are Microsoft Word, WordPerfect and AppleWorks.

Spreadsheets are programs that organize numeric data such as financial and budget reports. A spreadsheet is a rectangular grid of rows and columns. Put together, they form cells. These cells may contain text or numeric entries. Graphs can also be created in spreadheets. Formulas can also be used to make calculations easy in order to save time. A user can also insert graphs into a spreadsheet. Common Spreadsheet applications include Microsoft Excel, Apple iWork's Numbers and Corel Quattro Pro.

A DBMS is a program which creates, organizes and manages a database. All mass companies or organizations have a database to keep records and information. DBMSs have tools like the filter tool and the sort tool. Information stored can be quickly found and brought toghtether using queries, forms and reports. Examples of DBMSs are Microsoft Access, Corel Paradox and Lotus Approach.

Utility Suites contain more than one utility software bundled together. It is usually more convienient and cheaper to purchase utility suites. The utilities contained in utility suites usually focus on how the computer infrastructure operates. Utilities are often rather technical and aimed to people with an advanced level of computer knowledge. Examples of utilities are disk defragmenters, file managers and backup.