Compaq W4000 Manual De Usuario

Chapter 5  Input/Output Interfaces 

 

 
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 
 

Table 5-9. 

      Serial Interface Control Registers 

 

 

3F8h 

2F8h 

Receive Data Buffer 
Transmit Data Buffer 
Baud Rate Divisor Register 0 (when bit 7 of Line Control Reg. Is set) 

R 

W 
W 

3F9h 

2F9h 

Baud Rate Divisor Register 1 (when bit 7 of Line Control Reg. Is set) 
Interrupt Enable Register 

W 

R/W 

3FAh 

2FAh 

Interrupt ID Register 
FIFO Control Register 

R 

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 

 

 

 

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          Featuring the Intel Pentium 4 Processor