The PC87311A 12 incorporates a floppy disk controller (FDC) two full function UARTs a bidirectional parallel port and IDE interface control logic in one chip The PC87311A includes standard AT XT address decoding for on-chip functions and a Configuration Register offering a single chip solution to the most commonly used IBM PC PC-XT and PC-AT peripherals The PC87312 includes standard AT address decoding for on-chip functions and a Configuration Register set offering a single chip solution to the most commonly used ISA EISA and Micro Channel peripherals The on-chip FDC is software compatible to the PC8477 which contains a superset of the DP8473 and NEC mPD765 and the N82077 floppy disk controller functions The onchip analog data separator requires no external components and supports the 4 Mb drive format as well as the other standard floppy drives used with 5 25 and 3 5 media In the PC87311A the UARTs are equivalent to two INS8250N-Bs or NS16450s The bidirectional parallel port maintains complete compatibility with the IBM PC XT and AT In the PC87312 the UARTs are equivalent to two NS16450s or PC16550s The bidirectional parallel port maintains complete compatibility with the ISA EISA and Micro Channel parallel ports The IDE control logic provides a complete IDE interface except for the signal buffers The Configuration Registers consist of three byte-wide registers An Index and a Data Register which can be relocated within the ISA I O address space access the Configuration Registers