Hercules-EBX CPU User Manual V1.02
Page 40
6.2 COM Port / FPGA Control Registers
A set of registers is located at Address 0xA50-0xA5F for the purposes of controlling the enhanced
Serial Port features, as well as some FPGA control capability. Only two registers from this range
should be accessed by the user:
Address
Bit
Read - Write
Functional Description
0xA50
0
Read-Only
COM3 Address Selection (read from J5 – “A”)
1
Read-Only
COM4 Address Selection (read from J5 – “B”)
7-2
Read-Only
Unused
0xA51
0
Read / Write
COM3 Enable (1) / Disable (0)
1
Read / Write
COM3 : 0 = RS232
1 = RS485
2
Read / Write
COM4 Enable (1) / Disable (0)
3
Read / Write
COM4 : 0 = RS232
1 = RS485
7-4
Read / Write
Unused (set to 0)
0xA52-0xA5F
7-0
-
Reserved – do not access
Table 29: I/O COM3/4 Control Register Definition
6.3 Console Redirection to a Serial Port
In many applications without a video card it may be necessary to obtain keyboard and monitor
access to the CPU for configuration, file transfer, or other operations. Hercules-EBX supports this
operation by enabling keyboard input and character output onto a serial port (console redirection).
A serial port on another PC can be connected to the serial port on Hercules-EBX with a null
modem cable, and a terminal emulation program (such as HyperTerminal) can be used to
establish the connection. The terminal program must be capable of transmitting special
characters including F2 (some programs or configurations trap special characters).
The default Hercules-EBX BIOS setting enables console redirection onto COM2 during POST
(power on self-test). The communication parameters are 115.2Kbaud, N, 8, 1. When the CPU is
powered up, the BIOS will output POST information to COM2 and monitor it for any keyboard
activity. You can enter the BIOS by pressing F2 during this time. In the default configuration, after
POST is finished and the CPU boots, console redirection is disabled.
There are three possible configurations for console redirection:
♦
POST only (default)
♦
Always On
♦
Disabled
To modify the console redirection settings, enter the BIOS, select the Advanced menu, and then
select Console Redirection. In Com Port Address, select Disabled to disable the function, On-
board COM A for COM1, or On-board COM B for COM2 (default).
If you select Disabled, you will not be able to enter BIOS again during power-up through the serial
port. To reenter BIOS when console redirection is disabled, you must either install a PC/104 video
