Please enable JavaScript.

Coggle requires JavaScript to display documents.

UNDERSTAND THE IO SYSTEM - Coggle Diagram

- - - - • Acts as an interface with the CPU and memory
        via the system bus or central switch.
        • Acts as an interface with one or more
        peripheral devices by tailored data links.
- - - - ISOLATED I/O
        
        -Separate address spaces
        -Need I/O or memory select lines
        -Special commands for I/O
        -Limited Set
- - - - • Is the method of transferring data between
        the CPU and a peripheral such as a network
        adapter or an ATA storage device.
        • In general, programmed I/O happens when
        software running on the CPU uses instructions
        that access I/O address space to perform data
        transfers to or from an I/O device.
        • The best known example of a PC device that
        uses programmed I/O is the ATA interface.
    - - • Overcomes the processor having to wait long
        periods of time for I/O modules.
        • The processor does not have to repeatedly
        check the I/O module status.
    - - • Direct Memory Access is a method of
        transferring data between peripherals and
        memory without using the CPU.
        • Sometimes, CPU may not be fast enough to
        keep up with the peripheral.
        • In this case a special-purpose processor called
        a DMA controller (DMAC) can be used to
        transfer data between memory and I/O
        devices.
        
        DIRECT MEMORY ACCESS CONTROLLER (DMAC)
        
        • The DMA controller periodically takes over
        control of the system bus from the CPU.
        • DMAC generates address, data and control
        signals to transfer data between memory and
        I/O devices.