I heard about USB to LPT adapters that are capable of mapping PC legacy parallel port address. What is the level of such mapping? I mean - is it possible to access the adpater's pins by using 'in' or 'out' x86 assembler instructions (in Windows or Linux)? If not, what does it mean that the addresses are mapped? What kind of emulation is this? Thanks.
Marcin
A mapping from legacy I/O port addresses to a USB device is most likely handled by trapping the port access in kernel mode operating system code. For several generations of systems now, the operating system has been able to impose itself between application code and the hardware in such a way that even things that look like raw hardware access to the application are not necessarily so.
Effectively, when the processor comes upon that raw port access, it isn't executed but an operating system service routine is called instead.
