HP DC71XX, DX61XX Serial Interface Control, Table, Table, Serial Interface Control Registers, Serial Interface Configuration Registers

Input/Output Interfaces

The serial interface configuration registers are listed in the following table:

Table 5-11.

Serial Interface Configuration Registers

Index Address	Function	R/W
30h	Activate	R/W
60h	Base Address MSB	R/W
61h	Base Address LSB	R/W
70h	Interrupt Select	R/W
F0h	Mode Register	R/W

Serial Interface Control

The BIOS function INT 14 provides basic control of the serial interface. The serial interface can be directly controlled by software through the I/O-mapped registers listed in Table 5-12.

Table 5-12.

Serial Interface Control Registers

COM1	COM2
Addr.	Addr.	Register	R/W
3F8h	2F8h	Receive Data Buffer	R
		Transmit Data Buffer	W
		Baud Rate Divisor Register 0 (when bit 7 of Line Control Reg. Is set)	W
3F9h	2F9h	Baud Rate Divisor Register 1 (when bit 7 of Line Control Reg. Is set)	W
		Interrupt Enable Register	R/W
3FAh	2FAh	Interrupt ID Register	R
		FIFO Control Register	W
3FBh	2FBh	Line Control Register	R/W
3FCh	2FCh	Modem Control Register	R/W
3FDh	2FDh	Line Status Register	R
3FEh	2FEh	Modem Status	R

Technical Reference Guide 361834-002 5-13