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