Wednesday, May 18, 2011

IO mapped io

Since any dynamically-loaded driver module is attached to the existing kernel, any error in the driver will crash the entire system.

Resource allocation for a device is one of the main concerns for device-driver developers.

Resources are:
1. I/O memory
2. IRQs
3. Ports

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The most frequent job of any driver is transferring data between the computer and its external environment.
The external environment consists of external devices.

Three techniques are possible for I/O operations:
1. Programmed I/O
2. Interrupt-driver I/O
3. Direct Memory Access(DMA)

The PIO devices pass the data from the system to device or vice versa in two different ways:
1. I/O port
2. I/O memory mapped

PIO requires the CPU to move data to or from the device as each byte

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