DMA, IO Addresses and IRQ

This is a discussion on DMA, IO Addresses and IRQ within the Tech Board forums, part of the Community Boards category; I first wanted to figure out what exactly is IRQ so i started studying, and almost all my results on ...

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    Set Apart -- jrahhali's Avatar
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    DMA, IO Addresses and IRQ

    I first wanted to figure out what exactly is IRQ so i started studying, and almost all my results on what IRQ is was grouped with IO Addresses and DMA channels. So i read on all three of them but even though their explinations are different the way they work seems the same to me. Can someone clarify what these three terms are. thanks

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    Registered User FloatingPoint's Avatar
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    IRQ

    Abbreviation of interrupt request line, and pronounced I-R-Q. IRQs are hardware lines over which devices can send interrupt signals to the microprocessor. When you add a new device to a PC, you sometimes need to set its IRQ number by setting a DIP switch. This specifies which interrupt line the device may use. IRQ conflicts used to be a common problem when adding expansion boards, but the Plug-and-Play specification has removed this headache in most cases.
    DMA

    Short for direct memory access, a technique for transferring data from main memory to a device without passing it through the CPU. Computers that have DMA channels can transfer data to and from devices much more quickly than computers without a DMA channel can. This is useful for making quick backups and for real-time applications.
    Some expansion boards, such as CD-ROM cards, are capable of accessing the computer's DMA channel. When you install the board, you must specify which DMA channel is to be used, which sometimes involves setting a jumper or DIP switch.
    I/O

    Short for input/output (pronounced "eye-oh"). The term I/O is used to describe any program, operation or device that transfers data to or from a computer and to or from a peripheral device. Every transfer is an output from one device and an input into another. Devices such as keyboards and mouses are input-only devices while devices such as printers are output-only. A writable CD-ROM is both an input and an output device.
    From webopedia.com

    Just simple explanations, nothing more..
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