What is meant by Wait State?

What is meant by Wait State?
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Answer :

This state is used by slow peripheral devices. The peripheral devices can  transfer the data to or from the microprocessor by using READYinput line. The  microprocessor remains in wait state as long as READY line  is low. During the  wait  state,  the  contents  of  the  address,  address/data  and  control  buses  are  held  constant.
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List out the five categories of the 8085 instructions. Give examples of the instructions for each group.

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Description : What is an Operand?

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