Parallel Interface of microprocessor with I/O and memory
Modes of data transfer: There are four modes of data transfer which are described below:- 1. Simple Input and Output:- It is the most primitive form of data transfer. To get the data input from a simple switch such as thermostat into a microprocessor, we have to connect the switch to an input port line and read the switch. Similarly, to output data to a simple display device such as LED, we have to connect the LED buffer or an output port pin and output the logic level required to turn on the light. 2. Simple strobe I/O:- When a valid data is present on an external device only at certain time, it should be read at appropriate time. For example, input from a keyboard. When a key is pressed, it sends the ASCII code for the pressed key data lines and also sends out a strobe signal on another line to indicate that a valid data is present on the data lines. 3. ...