To return the byte read from machine port n.
n represents a valid machine port number within the range of 0 to 65535.
The INP function is one way in which a peripheral device may communicate with a GW-BASIC program.
INP is the complementary function to the OUT statement.
Upon execution, variable A contains the value present on port 56. The number returned will be within the range of 0 to 255, decimal.
The assembly language equivalent to this statement is
MOV DX,56 IN AL,DX