Principles of I/O software

Principles of I/O software

1. Goals of the I/O software

   • device independent
   • uniform naming
   • error handling
   • synchronous/asynchronous
   • buffering
   • sharing/dedicated

2. Programmed I/O

   • It is simple but has the disadvantages of tying up the CPU full time until all the I/O is done.

3. Interrupt-Driven I/O

   • Disadvantage: An interrupt occurs on every character. 

4. I/O using DMA

   • DMA is programmed I/O, only with the DMA controller doing all the work, instead of the main CPU.