25. Programmed I/O Overview
The chapter discusses the intricacies of Input/Output (I/O) operations, focusing on programmed I/O techniques and the necessity of I/O modules. It outlines the requirements for I/O commands, addressing schemes, and the distinction between memory-mapped I/O and isolated I/O. The significance of I/O modules is emphasized due to their need for managing diverse devices without directly connecting them to the CPU.
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What we have learnt
- CPU cannot multitask while waiting for I/O operations, leading to wasted processing time.
- I/O modules manage communication between the CPU and devices, enabling efficient data transfer.
- Two primary addressing schemes for I/O devices exist: memory-mapped I/O and isolated I/O.
Key Concepts
- -- Programmed I/O
- A method of I/O transfer where the CPU actively waits and checks the status of I/O devices to proceed with data transfer.
- -- I/O Modules
- Components that facilitate communication between the CPU and I/O devices, essentially acting as intermediaries to offload tasks from the CPU.
- -- MemoryMapped I/O
- A system where I/O devices share the same address space as memory, allowing the CPU to communicate with devices using standard read and write instructions.
- -- Isolated I/O
- A scheme where I/O devices have a separate address space from memory, requiring specific control signals to access either memory or I/O devices.
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