Memory Mapped I/O in 8085 Microprocessor

Memory Mapped I/O is a method of interfacing input/output (I/O) devices with the microprocessor. In this method, the I/O devices are treated as memory locations and accessed by the microprocessor using memory read and write instructions.

The 8085 microprocessor has a total addressable memory space of 64K (65536) bytes. Out of this, a portion of the memory space is reserved for I/O devices using memory mapped I/O technique.

Number of I/O Ports that can be accessed by Memory Mapped I/O

The total number of I/O ports that can be accessed by memory mapped I/O in 8085 microprocessor is determined by the number of memory locations reserved for I/O devices.

In 8085, the memory locations reserved for I/O devices are from 00H to FFH. This means that a total of 256 memory locations are reserved for I/O devices.

Each I/O device can be assigned one or more memory locations depending on its requirements. For example, a simple input device such as a switch can be assigned one memory location, whereas a complex output device such as a printer may require multiple memory locations.

Therefore, the number of I/O ports that can be accessed by memory mapped I/O in 8085 microprocessor is 256.

Conclusion

In summary, the 8085 microprocessor has a total addressable memory space of 64K, out of which 256 memory locations are reserved for I/O devices using memory mapped I/O technique. Therefore, the number of I/O ports that can be accessed by memory mapped I/O in 8085 microprocessor is limited to 256.