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2 System Board
Devices on the ISA Bus
Devices on the ISA Bus
The Super I/O Controller (NS 82317)
The Ultra I/O chip (NS 82317) provides the control for two FDD devices,
one serial port and one bidirectional multi-mode parallel port.
Serial / parallel
communications ports
The 9-pin serial port (whose pin layouts are depicted on page 71) supports
RS-232-C and are buffered by 16550A UARTs, with 16 Byte FIFOs. They can
be programmed as COM1, COM2, COM3, COM4, or disabled.
The 25-pin parallel port (also depicted on page 71
) is Centronics
compatible, supporting IEEE 1284. It can be programmed as LPT1, LPT2, or
disabled. It can operate in the following four modes:
❒ Standard mode (PC/XT, PC/AT, and PS/2 compatible).
❒ Bidirectional mode (PC/XT, PC/AT, and PS/2 compatible).
❒ Enhanced mode (enhanced parallel port, EPP, compatible).
❒ High speed mode (MS/HP extended capabilities port, ECP, compatible).
FDC The integrated flexible disk controller (FDC) supports any combination of
two of the following: tape drives, 3.5-inch flexible disk drives, 5.25-inch
flexible disk drives. It is software and register compatible with the 82077AA,
and 100% IBM compatible. It has an A and B drive-swapping capability and a
non-burst DMA option.
RTC The real-time clock (RTC) is 146818A-compatible. With an accuracy of
20 ppm (parts per million). The configuration RAM is implemented as 256
bytes of CMOS memory.
Keyboard and Mouse
Controller
The computer has an 8042-based keyboard and mouse controller. The
connector pin layouts are shown on page 71
.
ISA Device Index Data
Ultra I/O
2Eh 2Fh
Little Ben (HP ASIC)
96h 97h