$\underline{\textbf{Answer:}\Rightarrow}$
$\underline{\textbf{Explanation:}\Rightarrow}$
Opcode |
Reg1 |
Reg2 |
Immediate Operand |
Number of instructions which are supported $=70$
$13-\text{bits}$ support the maximum value of immediate operand $=8191$
Now,
Number of bits needed for opcode $=7\;\text{bits}$
Number of bits left to represent register bits $=12$
which means $6-\text{bits}$ per register.
Hence, at max. $\mathbf{64}$ registers.
$\therefore \;\mathbf{(b)}$ is the correct option.