Control memory of a micro$-$program based computer system is $4k$ words of $25$ bit each. Each micro$-$

$[2]$

program subroutine required at least five words of control memory. If op$-$code bit pattern is $00000100$ and instruction is store in main memory of computer system at location $20H.$

How many bits are there in the control address register?

How many bits are there in each of the four inputs going into multiplexers of next address generator circuit?

Draw the mapping procedure for instruction to address of control memory.

Write a micro$-$program subroutine for STORE instructions, including Indirect and Fetch subroutine.