when we are using micro-programmed control unit...
we have a special memory where we store all control signals ...and that memory is called as control memory..
now each entery in control memory is called as control word....which contain set of control signals ...
while there is a control address register which takes input as a address and gives output as control word present as that address...
ex
SAY WE HAVE 1024 CONTROL WORDS PRESENT IN MEMORY .....AND EACH ENTRY CONTAIN 32 SIGNALS (that is 32 bits like 0 and 1 )...SO TO DETECT ONE WORD WE NEED 10 BITS ...SO WHEN WE PROVIDE ADDRESS TO CONTROL ADDRESS REGISTER SAY 222..THEN WORD PRESENT AT LOCATION 222 WILL BE GIVEN AS OUTPUT...
NOW AS I TOLD 32 BITS ARE PRESENT IN CONTROL WORD...LIKE 1000100,.......11 WHERE 1 DENOTE CONTROL SIGNAL IS GIVEN WHILE 0 MEANS CONTROL SIGNAL IS ABSENT ...