A wait state is a delay experienced by a computer processor
when accessing external memory or another device that is
slow to respond.  the vice versa also cone into scenario

A wait state is a delay experienced by a microprocessor 
when accessing external memory or another device that is 
slow to respond.  the vice versa also come into scenario. 
Now, to be able to access slow memory the microprocessor 
must be able to delay the  transfer until the memory access 
is complete. One way is to increase the micro processor 
clock period by reducing the  clock frequency. Some micro 
processors provide a special control input called READY to 
allow the memory to set its own memory cycle time. If after 
sending an address out, the microprocessor does not receive 
a READY input from  memory, it enters a wait state for as 
long as the READY  line is in 0 state. When the memory 
access is completed the READY goes high to indicate that 
the memory is ready for specified transfer.