Drawbacks of Programmed and Interrupt-Driven I/O

I/O Operations

• A drawback of interrupt-driven I/O is that it can cause the processor to be interrupted frequently, reducing its ability to perform other tasks.

DMA (Direct Memory Access)

• DMA differs from programmed and interrupt-driven I/O in that it allows peripherals to access memory directly, without involving the processor.
• The purpose of cycle stealing in DMA is to allow the DMA module to access the bus and transfer data to or from memory, without interrupting the processor.
• The DMA module needs to use the bus only when the processor does not need it, to avoid conflicts and ensure efficient data transfer.
• DMA stands for Direct Memory Access, which is a method of transferring data between peripherals and memory without involving the processor.
• When the processor issues a command to the DMA module for reading or writing a block of data, the DMA module takes control of the bus and transfers the data directly, freeing the processor to perform other tasks.
• The role of the DMA module in I/O operations is to manage the transfer of data between peripherals and memory, reducing the processor's workload and improving system efficiency.

Evolution of I/O Operations

• The evolutionary step in I/O operations when interrupts are employed is that it allows the processor to focus on other tasks while the I/O operation is being performed, improving system efficiency.

I/O Processor

• The architecture with an I/O processor benefits I/O operations by allowing the I/O processor to handle I/O tasks, freeing the main processor to focus on other tasks and improving system efficiency.