HP Compaq D315 Technical Reference Manual page 92

Chapter 5 Input/Output Interfaces
5.4.2.2 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 5-9.
Table 5–9. Serial Interface Control Registers
COM1 COM2
Addr. Addr.
3F8h 2F8h
3F9h 2F9h
3FAh 2FAh
3FBh 2FBh
3FCh 2FCh
3FDh 2FDh
3FEh 2FEh
5-10 Compaq D315 and hp d325 Personal Computers
Featuring the AMD Athlon XP Processor
Table 5-9.
Serial Interface Control Registers
Register
Receive Data Buffer
Transmit Data Buffer
Baud Rate Divisor Register 0 (when bit 7 of Line Control Reg. Is set)
Baud Rate Divisor Register 1 (when bit 7 of Line Control Reg. Is set)
Interrupt Enable Register
Interrupt ID Register
FIFO Control Register
Line Control Register
Modem Control Register
Line Status Register
Modem Status
Second Edition – April 2003
R/W
R
W
W
W
R/W
R
W
R/W
R/W
R
R