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
Table
|
| Table |
|
|
| 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 |
Second Edition – April 2003