Page 157 - Digital Electronics by harish

Steps for memory operations (memory read and memory write) :

1. When the memory related instructions like LDA and STA are used, the
microprocessor places the 16-bit address on the address bus.
2. is activated for read operation and is activated for write operation.

Steps for I/O operations (I/O read and I/O write) :

The same steps used for memory operations are used for I/O operations also.

5.4.1.2 I/O mapped I/O

In this method, I/O devices are treated as I/O devices and memory is
treated as memory. Separate address space is used for memory and I/O. The I/O
mapped I/O scheme is shown in figure 5.9.
0000 - FFFF

A0 – A7

A8 –
A15

Memory
D0 – D7
A15

/

00 - FF
A0 – A7

D0 – D7
A15
I/O

/

Figure 5.9 : I/O mapped I/O scheme

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