In what circumstances would a critical region appear when using interrupts? What are the possible programming solutions to this problem? What does DMA stand for? Where and when would you expect your...

In what circumstances would a critical region appear when using interrupts? What are the possible programming solutions to this problem?

What does DMA stand for? Where and when would you expect your PC to employ DMA? If DMA is used to routinely update a large array of data, what precautions would a programmer need to take?