| Memory Mapped | Input/output Mapped |
|---|---|
| 16-bit device address is used. | 8-bit device address is used. |
| Data is transferred between any general-purpose register and I/O port. | Data is transferred only between accumulator and I/O port. |
| The memory map (64K) is shared between I/O device and system memory. | The I/O map is independent of the memory map, 256 input devices and 256 output devices can be connected. |
| More hardware is required to decode 16-bit address. | Less hardware is required to decode 8-bit address. |
| Arithmetic or logical operations can be directly performed with I/O data. | Arithmetic or logical operations cannot be directly performed with I/O data. |
| All instructions related to memory can be used for data transfer. | Only IN and OUT instructions can be used for data transfer. |
| A large number of I/O ports can be interfaced. | Only 256 ports can be interfaced. |
| Less memory space is available due to partitioning. | Whole address space is available. |
| The devices are accessed by memory read and memory write cycle. | The devices are accessed by I/O read and I/O write cycle. |
| Arithmetic and logical operations can be directly performed with I/O data. | Arithmetic and logical operations cannot be directly performed with I/O data. |
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