Question

Consider the following hypothetical microprocessor. Assume this processor uses a 32-bit address and 32-bit data bus. Consider a 4-bit I/O port number. How many 8-bit I/O ports can be supported?

Answer 1

Given,

I/O Port number is of 4 bits.

• Number of I/O Ports depends upon size of I/O port (4-bit) in this case.
• Size of I/O port will not affect the number of I/O ports it supports.
• So, the number of ports it supports depends only only on size of port. So whether it is 4 bit, 8 bit or 16 bits, or n-bits it supports same number of I/O ports. In this case it is 2⁴ = 16.

Number of input ports the microprocessor support with 4 bit I/O ports = 2⁴ = 16. So microprocessor can support 16 8-bit input ports and 2⁴ = 16 8-bit output ports.