Apparatus for decoding and providing the decoded addresses to industry standard PCMCIA card through the data lines of the parallel port

摘要

An interface circuit used to connect industry standard PCMCIA (Personal Computer Memory Card International Association) cards to a personal computer via a standard parallel printer port. The invention utilizes a mechanism which enables direct access to each I/O or memory address on a PCMCIA card independently. This is done by transferring an I/O or memory address in a PCMCIA card via the data lines of the parallel port, decoding this address, and providing the decoded address to the PCMCIA card. As a result, application software which accesses the PCMCIA card can run without modification. All that is needed is add-on code which captures and re-routes accesses generated by the application software to the parallel port. This add-on code captures the I/O instructions targeted at the I/O device associated with the PCMCIA card and replaces them with sequences of instructions routed through the parallel port. Another feature of the present invention is the generation of an internal ISA-like bus to handle card interrupts. This means that interrupts generated by the PCMCIA card are sensed by the internal bus of the invented parallel port interface unit, and then translated by the invented parallel port interface unit so that the host microprocessor services the interrupt.