Isolated vs. Memory mapped I/O
Isolated vs. Memory mapped I/O
Isolated I/O
- Separate I/O read/write control lines in addition to memory read/write control lines
- Separate (isolated) memory and I/O address spaces
- Distinct input and output instructions
Memory-mapped I/O
- A single set of read/write control lines (no distinction between memory and I/O transfer)
- Memory and I/O addresses share the common address space
- reduces memory address range available
- No specific input or output instruction
- The same memory reference instructions can be used for I/O transfers
- Considerable flexibility in handling I/O operations