PC87306 datasheet(19/110 Pages) NSC

19 / 110 page

20 Configuration Registers (Continued)

TLC12379 – 23

TLC12379 – 25

TLC12379 – 24

FIGURE 2-1 PC87306 Configuration Registers

(Continued)

23 HARDWARE CONFIGURATION

During reset 1 of 4 possible sets of default values are load-

ed into the first five Configuration Registers A strapping

option on two pins (CFG0 1) selects the set of values that is

loaded This allows for automatic configuration without soft-

ware intervention Table 2-1 shows the 4 possible default

configurations The default configuration can be modified by

software at any time after reset by using the access proce-

dure described in the Software Configuration Section

24 INDEX AND DATA REGISTERS

Another general aspect of the Configuration Registers is

that the Index and the Data Register pair can be relocated

to any one of two locations This is controlled through a

hardware strapping option on two pins (BADDR01) and it

allows the registers to avoid conflicts with other adapters in

the IO address space Table 2-2 shows the address op-

tions

TABLE 2-2 Index and Data Register

Optional Locations

BADDR1

BADDR0

Index Addr

Data Addr

398

399

26E

26F

15C

15D

TABLE 2-1 Default Configurations Controlled by Hardware on Reset

Configuration

Configuration Register Reset Values (Binary)

Activated Functions

on Reset

Pins

CFG1

CFG0

FER

FAR

PTR

KRR

SCF0

01001011

00000001

00000x00

0x001101

0x110000

PRI (FDC) PRI (IDE)

LPTA COM1 GPIO

KBC RTC

Reserved Mode

00001111

00010001

00000x00

0x001101

0x000000

PRI (FDC) LPTA COM1

COM2 (non-IR) KBC RTC

00000000

00010000

00000x00

0x000001

0x000000

All Modules Disabled

(powered-down) except KBC

Where

PRI

is the PRImary floppy or IDE address 3F0 – 7h or

1F0 – 7 3F6 3F7h)

COM1

is the UART address at 3F8 – 3FFh

COM2

is the UART address at 2F8 – 2FFh

LPTA

is the Parallel Port address at 3BC – 3BEh

GPIO

is the General Purpose IO ports 1 and 2 addresses

at 78h and 79h

KBC

is the Keyboard Controller function

using an

X1 d 3 clock

RTC

is the Real-Time Clock function

PC87306 Datasheet(PDF) 19 Page - National Semiconductor (TI)

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