pc87317vul National Semiconductor Corporation, pc87317vul Datasheet - Page 27

• Manufacturer Part Number: pc87317vul
• Description: Pc87317vul/pc97317vul Superi/o Plug And Play Compatible With Acpi Compliant Controller/extender
• Manufacturer: National Semiconductor Corporation

2.0 Configuration
The PC87317VUL is partially configured by hardware, dur-
ing reset. The configuration can also be changed by soft-
ware, by changing the values of the configuration registers.
The configuration registers are accessed using an Index
register and a Data register. During reset, hardware strap-
ping options define the addresses of the configuration reg-
isters. See Section 2.1.2 "The Index and Data Register
Pair".
After the Index and Data register pair have determined the
addresses of the configuration registers, the addresses of
the Index and Data registers can be changed within the ISA
I/O address space, and a 16-bit programmable register con-
trols references to their addresses and to the addresses of
the other registers.
This chapter describes the hardware and software configu-
ration processes. For each, it describes configuration of the
Index and Data register pair first. See Sections 2.1 "HARD-
WARE CONFIGURATION" and 2.2 "SOFTWARE CON-
FIGURATION" on page 28.
Section 2.3 "THE CONFIGURATION REGISTERS" on
page 29 presents an overview of the configuration registers
of the PC87317VUL and describes each in detail.
2.1 HARDWARE CONFIGURATION
The PC87317VUL supports two Plug and Play (PnP) con-
figuration modes that determine the status of register ad-
dresses upon wake up from a hardware reset, Full Plug and
Play ISA mode and Plug and Play Motherboard mode.
2.1.1
During reset, strapping options on the BADDR0 and
BADDR1 pins determine one of the following modes.
BADDR1
Full Plug and Play ISA mode – System wakes up in
Wait for Key state.
Index and Data register addresses are as defined by Mi-
crosoft and Intel in the “Plug and Play ISA Specification,
Version 1.0a, May 5, 1994.”
Plug and Play Motherboard mode – system wakes up
in Config state.
0
1
1
Wake Up Options
BADDR0
0
1
x
015Ch Read/Write
002Eh Read/Write
Index Register
Write Only
0279h
TABLE 2-1. Base Addresses
Address
Configuration
Read: RD_DATA Port
015Dh Read/Write
002Fh Read/Write
27
Data Register
Write: 0A79h
2.1.2
During reset, a hardware strapping option on the BADDR0
and BADDR1 pins defines an address for the Index and
Data Register pair. This prevents contention between the
registers for I/O address space.
TABLE 2-1 "Base Addresses" shows the base addresses
for the Index and Data registers that hardware sets for each
combination of values of the Base Address strap pins
(BADDR0 and BADDR1). You can access and change the
content of the configuration registers at any time, as long as
the base addresses of the Index and Data registers are de-
fined.
When BADDR1 is low (0), the Plug and Play (PnP) protocol
defines the addresses of the Index and Data register, and
the system wakes up from reset in the Wait for Key state.
When BADDR1 is high (1), the addresses of the Index and
Data register are according to TABLE 2-1 "Base Address-
es", and the system wakes up from reset in the Config state.
This configures the PC87317VUL with default values, auto-
matically, without software intervention. After reset, use
software as described in Section 2.2 "SOFTWARE CON-
FIGURATION" on page 28 to modify the selected base ad-
dress of the Index and Data register pair, and the defaults
for configuration registers.
The Plug and Play soft reset has no effect on the logical de-
vices, except for the effect of the Activate registers (index
30h) in each logical device.
The PC87317VUL can wake up with the FDC, the KBC and
the RTC either active (enabled) or inactive (disabled). The
other logical devices and the internal on-chip clock multipli-
er wake up inactive (disabled).
The BIOS configures the PC87317VUL. Index and Data
register addresses are different from the addresses of
the Plug and Play (PnP) Index and Data registers. Con-
figuration registers can be accessed as if the serial iso-
lation procedure had already been done, and the
PC87317VUL is selected.
The BIOS may switch the addresses of the Index and
Data registers to the PnP ISA addresses of the Index
and Data registers, by using software to modify the base
address bits, as shown in Section 2.4.4 "SuperI/O Con-
figuration 2 Register (SIOC2)" on page 38.
The Index and Data Register Pair
Wake up in Wait for Key state
Wake up in Config state
Wake up in Config state
PnP Motherboard Mode
PnP Motherboard Mode
Configuration Type
Full PnP ISA Mode
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