6. Appendix
COM I/O Address and Register Function
The following table lists the I/O addresses in case of COM 1.
Table 6.4. I/O Address
I/O address
DLAB
Read/Write
03F8H
0
1
03F9H
1
0
03FAH
X
03FBH
X
03FCH
X
03FDH
X
03FEH
X
03FFH
X
DLAB (Divisor Latch Access Bit) : The value in bit 7 of the line control register.
60
W
Transmitter holding register
R
Receive buffer register
W
Divisor latch register
W
Divisor latch register
W
Interrupt enable register
R
Interrupt ID register
W
Line control register
W
Modem control register
R
Line status register
R
Modem status register
R/W
Scratch register
Register
THR
RBR
DLL
DLM
IER
IIR
LCR
MCR
LSR
MSR
SCR
IPC-BX800 Series User's Manual