Why I/O devices cannot be connected directly to the systembus? What are the important functions of I/O system? Explainthe Programmed I/O

I/O devices cannot be connected directly to the system bus because they operate at different speeds and have different data transfer protocols. The system bus is designed to handle high-speed data transfer between the CPU and main memory, while I/O devices typically operate at slower speeds and use different communication protocols.

The important functions of an I/O system include:

1. Device Communication: The I/O system facilitates communication between the CPU and the I/O devices. It manages the data transfer between the CPU and the devices, ensuring that the data is correctly transmitted and received.

2. Device Control: The I/O system controls the operation of the I/O devices. It initiates device operations, such as reading or writing data, and manages the status and control signals of the devices.

3. Data Buffering: The I/O system provides data buffering capabilities to temporarily store data being transferred between the CPU and the I/O devices. This buffering helps to smooth out any speed differences between the CPU and the devices.

4. Error Handling: The I/O system handles errors that may occur during data transfer. It detects and reports errors, and takes appropriate actions to recover from them.

Programmed I/O is a method of data transfer between the CPU and an I/O device. In this method, the CPU directly controls the data transfer by executing specific instructions. The CPU sends commands to the I/O device to initiate the transfer, and then waits for the device to complete the operation before proceeding with other tasks.

During programmed I/O, the CPU is actively involved in the data transfer process, which can be time-consuming and inefficient for large amounts of data. However, it provides a simple and straightforward way to control I/O devices and is suitable for devices that require low data transfer rates or have simple communication protocols.

Overall, the I/O system plays a crucial role in managing the communication and control of I/O devices, ensuring efficient data transfer between the CPU and the devices.