Contec BX-100n-DC5000-C01, User Manual, Page: 132 / 145

7. Appendix
BX-100n User’s manual
125
COM I/O Address and Register Function
The following table lists the I/O addresses in case of COM 1.
Table 7.4. I/O Address
I/O address DLAB Read/Write Register
W Transmitter holding register THR 0
R Receive buffer register RBR
03F8H
1 W Divisor latch register (LSB) DLL
1 W Divisor latch register (MSB) DLM 03F9H
0 W Interrupt enable register IER
03FAH X R Interrupt ID register IIR
03FBH X W Line control register LCR
03FCH X W Modem control register MCR
03FDH X R Line status register LSR
03FEH X R Modem status register MSR
03FFH X R/W Scratch register SCR
DLAB (Divisor Latch Access Bit) : The value in bit 7 of the line control register.