**A computer has 32 registers, ALU has 64 operations. All are connected to a common bus system. Formulate a control word for the computer; specify the bits in each field of the control words. 5m Dec2005**

Please note the following points:

- The opcode size is 7 bits. So, in general it will have 2
^{7}= 64 operations. - There are three bits for addressing modes. Therefore, there are 2
^{3}= 8 different addressing modes possible for this machine. (Assumption) - The last field (10 – 32 bits = 22 bits) here is the operands or the addresses of operands field.

Total general purpose registers = 32

All Register equal size = 32 bits (Assumption)

Registers used as stack for subroutine calls = 16

Memory word size = 32 bits (Assumption)

Control word = Instructions size = one memory word = 32 bits

Opcode = 7 bits

Addressing mode = 3 bits

Remaining bits = operand addresses

**Control Word:-**