Commodore PC - Page 296

224 MS-DOS User's Reference
(l)nput
Using the Input
command
Input
Purpose:
Inputs and displays one byte from the port specified by value.
Syntax:
lvalue
Comment:
A 16-bit port address is allowed.
Example:
Suppose you type the following command:
I2F8
Suppose also that the byte at the port is 42H. Debug would input
the byte and then display the following:
42
u
u
u
u
u
u
u