consider a computer with a CPU with instruction counter IC 1

consider a computer with a CPU with instruction counter (IC) 16-bit and instruction register (IR) of 38 bits. his instructions have two operands of the same size (16 bits) and, of course, an operation code question is:
a) where the instruction size?
b) what is the size of the instruction code field?

c)whereas the basic configuration of this machine is 16 kbytes of memory, up to size the memory can be expanded?

Solution

Usually in a CPU the instruction register (IR) is used to store the instruction which is currently being executed or decoded in the pipeline.

a)

Since the instruction register is 38 bits wide the size of the instruction must be 38 bits.

b)

Instruction contains two operands each of 16 bits. So total space occupied in instruction by operands is 16*2=32 bits. Now the instruction code size must be 38-32 = 6 bits.

c)

We know that the instruction counter size is 16 which means that 2^16 addresses can be stored in this cpu. So the memory of the CPU will be 2^16 = 65536 = 64 kb