rs232

MIPS处理器的bootloader,龙芯就是用的修改过的PMON2

		RS232 Cabling Requirements
		RS232 Cabling Requirements

Some hosts require the hardware flow control signals to be connected
before they will send and receive data via the RS232 ports. This may be
true even if you have explicitly disabled the hardware flow control.

LSI Logic's Evaluation boards require only pins 2, 3, and 5 to be
connected (except CON7 on the SDP1000).

	HOST					   LSI EVAL BOARD
====================				   ==============
       DB25    DB9					DB9
       PIN     PIN					PIN

RXD	2	3 ------------------------------------- 3
GND	7	5 -------------------------------------- 5

RTS	4	7 --+
                    |
CTS	5	8 --+

DSR	6	6 --+
                    |
DCD	8	1 --+
                    |
DTR	20	4 --+