Understanding,the,Software,Lay computer Understanding the Software Layers of a Computer

Gone are those times when the companies and the organisations didn't need a hi-tech system to handle them. Owing to the considerable increase in the business sector and thus, an enormous increase in the complexity of the organisational struc ----------------------------------------------------------Permission is granted for the below article to forward,reprint, distribute, use for ezine, newsletter, website,offer as free bonus or part of a product for sale as longas no changes a

----------------------------------------------------------Permission is granted for the below article to forward,reprint, distribute, use for ezine, newsletter, website,offer as free bonus or part of a product for sale as longas no changes are made and the byline, copyright, and theresource box below is included. ----------------------------------------------------------Understanding the Software Layers of a ComputerBy Stephen BucaroYou're typing in a word processor and you decide it wouldbe nice to have a hard copy. You select File | Print inthe menu and the printer comes to life, feeding out a copyof your document on paper. It seems like a simple process,but in reality your request passed through many layers ofsoftware before reaching your printer.Although you requested the print through a menu of yourword processing application, that application did notcontact the printer directly. Instead, the aplication madea request to the computer's operating system. Remember,today's computers are multi-tasking. That means they canperform more than one task at a time. The operating systemmediates the priority of multiple tasks requesting to usea hardware device.The operating system did not contact the printer directly.Remember, today's computers can have a multitude ofdifferent hardware attached. There are thousands ofdifferent kinds of printers, and a computer may haveseveral printers attached. Instead, the operating systemcommunicates with a piece of software called a "devicedriver", specific to the printer that you selected.The device driver did not contact the printer directly.Instead, the device driver contacted a program called theBIOS (Basic Input/Output System). Whereas all the programsup to this point had been loaded from the computers harddrive, the BIOS was loaded from a memory chip. Finally,the BIOS communicates directly with the electroniccircuits of the printer.[Application]--[Operating System]--[Device Driver]--[BIOS]--[Hardware]The above explanation describes the common software layersof a computer. Each of the software layers described abovemay itself consist of many layers. An application maycommunicate with the operating system through a piece ofsoftware called a DLL (Dynamic Link Library).The operating system especially is constructed of manylayers. Sometimes the operating system is described to belike an onion. At the center of the onion is the operatingsystems kernal. Only other layers of the operating systemare allowed to communicate directly with the kernal. Theouter layer of the operating system consists of programscalled services which applications can communicate withdirectly.It is possible to communicate with the printer directly(well almost). Most operating systems have a command lineinterface that lets users communicate more directly withthe operating system and with hardware devices through theBIOS. The most familiar command line interface is the DOSCommand Prompt.At the DOS command prompt you can type "print" followed bythe name of a document and a printed copy will be generated.But don't expect fancy fonts or formatting. Although thecommand line interface can be very powerful for some tasks,for other tasks it is very crude.When you first start your computer, it has no softwareloaded. You could say your computer is "brain dead". Itdoesn't even know how to use the hard disk drive to loadthe operating system.The BIOS is non-volatile memory built into the computersmotherboard. Non-volatile means that the instructions inthe memory are not lost when you turn the power off.When you first start your computer, it is hard-wired tostart reading the first instruction in the BIOS. The BIOSis not usually all in a single chip. As the BIOS starts,it looks for other parts of the BIOS that reside in chipson expansion cards. From these instructions, it learns howto check itself out (Power-on Self Test) and how tolocate and load the operating system. The computer "BOOTS"(pulls itself up by its bootstraps).The last thing the BIOS does is locate the drive containingthe operating system and begin loading the operating system.Because the hard disk has vastly more storage capacity thana BIOS chip, the operating system software can be large andpowerful. As the operating system loads, it begins loadingdevice drivers and configuring the hardware.In the early days, BIOS programs where stored in ROM (readonly memory). Todays computers usually store BIOS programsin a type of memory, called "Flash memory" that can berewritten. This allows you to reprogram the BIOS to fixbugs, or to update it. For example, You might download aBIOS update program from the Web and run it from a floppy disk.The important thing to understand is that your computer haslayers of software. You should understand where each layerresides in the path from user to hardware. You should nowunderstand that when you dial out with your web browser,the request is passed to the operating system, which passesit to the modem driver, which communicates with a BIOS onthe modem. That BIOS is the program that actually works theelectronics of your modem.Resource Box:----------------------------------------------------------Copyright(C)2004 Bucaro TecHelp. To learn how to maintainyour computer and use it more effectively to design a Website and make money on the Web visit http://bucarotechelp.comTo subscribe to Bucaro TecHelp Newsletter Send a blankemail to mailto:bucarotechelp-subscribe@topica.com---------------------------------------------------------- Article Tags: Software Layers, Operating System