Com1 Port Header; Serial Interface Programming; Table 5-8. Serial Interfacec - Compaq Evo D500 Technical Reference Manual

5.4.2 COM1 PORT HEADER

The Small Form Factor system board includes a header that connects to the COM1 port's DB-9
connector on the rear chassis I/O panel through a cable assembly. The header pinout is shown in
the following figure:
Figure 5-4. COM1 Serial Interface Header (Small Form Factor system board only)

5.4.3 SERIAL INTERFACE PROGRAMMING

Programming the serial interfaces consists of configuration, which occurs during POST, and
control, which occurs during runtime.
5.4.3.1 Serial Interface Configuration
The serial interface must be configured for a specific address range (COM1, COM2, etc.) and also
must be activated before it can be used. Address selection and activation of the serial interface are
affected through the PnP configuration registers of the LPC47B357 I/O controller.
The serial interface configuration registers are listed in the following table:
Table 5–8. Serial Interface Configuration Registers
Serial Interface Configuration Registers
Index
Address Function
30h Activate
60h Base Address MSB
61h Base Address LSB
70h Interrupt Select
F0h Mode Register
NOTE:
Refer to LPC47B357 data sheet for detailed register information.
CD 1 6 DSR
RX Data 2 7 RTS
TX Data 3 8 CTS
DTR 4
9 RI
Gnd 5
Table 5-8.
Compaq Deskpro and Evo Personal Computers
Featuring Intel Celeron and Pentium III Processors
Fifth Edition - March 2002
Technical Reference Guide
R/W
R/W
R/W
R/W
R/W
R/W
5-9