Just dropping some info , my book says " To display the current status of a serial port , enter the MODE COM# command without any parameters . To display the status of all the DOS devices attached to your computer , enter the MODE command alone . "
MODE COM# baud, parity, data, stop, retry
#= 1 , 2 , 3 , 4 colon after number is optional
baud= 110, 150, 300, 600, 1200, 2400, 4800, 9600, or 19200 can enter just first two digits
parity= N for NONE , O for ODD , E for EVEN , M for MARK , S for SPACE default is E
data= 5 through 8 default is 7
stop= 1 , 1.5 , 2 110 baud default is 2 , otherwise default is 1
retry= instructs DOS how to handle timeouts [ B , Return busy when port is busy ][ E , Return error ][ P , Retry until accepted ][ R , Return ready ] continuous retries on dos 5 and up use B , dos 4 and lower use P , might hang computer but can stop continuous retries with Ctrl-Break [ N or NONE take no action , default]
Hope it helps , seems like all the important stuff for MODE and serial ports.