20
2 System Board
Devices on the ISA Bus
Devices on the ISA Bus
Super I/O Controller
The
Super I/O
chip (NS PC87308, or the NS PC87307 on later models) is
contained within a 160-pin PQFP package. The chip provides the control for
the following devices.
Serial / parallel
communications ports
The two 9-pin serial ports (whose pin layouts are depicted on page 33)
support RS-232-C and are buffered by 16550 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 33) is Centronics
compatible, supporting IEEE 1284. It can be programmed as LPT1, LPT2, or
disabled. It can operate the 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).
ISA Device
Index
Data
Super I/O
15Ch
15Dh
Little Ben
496h
497h
Function
Logical device number
Keyboard controller
0
Mouse controller
1
RTC and Advance power supply controller (APC)
2
Flexible disk controller
3
Parallel port controller
4
UART2 and IR controller
5
UART1 controller
6
General purpose I/O (GPIO)
7
Power management
8
