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Peripherals
Super I/O Chip: Compatibility I/O Controller
The National Semiconductor PC87307VUL Super I/O chip (87307) supports
two serial ports, one parallel port, diskette drive, PS/2-compatible keyboard
and mouse, and integrated RTC. The motherboard provides the connector
interface for each port.
Serial Ports
Both serial ports are relocatable. By default, port A appears at the onboard
DB9 connector, port B on the 10-pin header. Each serial port can be set to
one of four different COMx ports and can be enabled separately. When
enabled, each port can be programmed to generate edge- or level-sensitive
interrupts. When disabled, serial port interrupts are available to add-in
boards.
Parallel Port
The 87307 provides one IEEE 1284-compatible 25-pin bidirectional EPP
(supporting levels 1.7 and 1.9). BIOS programming of the 87307 registers
enable the parallel port and determine the port address and interrupt.
When disabled, the interrupt is available to add-in boards.
Diskette Port
The floppy disk controller (FDC) on the 87307 is functionally compatible
with 82077SL, 82077AA, and 8272A diskette drive controllers. The
motherboard provides the 24 MHz clock, termination resistor package, and
chip selects. All other FDC functions are integrated into the 87307,
including PLL separator and 16-byte first-in, first-out (FIFO).
16
Chapter 1 - Motherboard Description
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