4.2.2 I/O Subsystem
The I/O subsystem, implemented with an NS87334 VJG Super I/O
Controller Chip, provides for such functions as internal Hard Drive control,
floppy drive control, and serial and parallel ports. The Super I/O Controller
includes the following features:
•100 percent compatible with ISA, EISA, and Micro-channel architectures
• Built-in Floppy Disk Controller
•Software compatible with the DP8473, the 765A and N82077
•16-byte FIFO (default disabled)
•Burst and Non-burst modes
•Perpendicular Recording drive support
•New high-performance internal digital data separator (no external
filter components required)
•Low-power CMOS with enhanced power-down mode
•Automatic media-sense support
•Two UARTs
•Software compatible with the PC16550A and PC16450
•MIDI compatible
•Infrared support on UART2 (IRDA-compliant)
•Bidirectional Parallel Port
•Enhanced Parallel Port (EPP) compatible
•Extended Capabilities Port (ECP) compatible, including level 2
support
•Bidirectional under either software or hardware control
•Compatible with ISA, EISA, and Micro Channel architectures
•Ability to multiplex FDC signals on parallel port pins for external
FDD
•Includes protection circuit against damage caused when printer is
powered up, or operated at higher voltages
• Integral IDE controller
•Provides a complete IDE interface with DMA control (except for
optional buffers)
Theory of Operation 4-3