Date   : Tue, 31 Dec 1985 00:31:11 EST
From   : "Paul R. Grupp" <GRUPP@mit-mc.ARPA>
Subject: 8251 Usart

[ I don't think the mailer will hack your return address, so here it
  goes to the list at large ]

First of all I think you want 8 data bits not 7, and the usual 1
stop bit, 16X baud clock.  Second, to RE-init the 8251 you first have
to send a command to it to turn it off, THEN the reset, init, and
enable sequence.  For 8 data, 1 stop, 16X here are the values in HEX.
0AAh 040h 0CEh 017h.  Also you *CAN* change the baud rate (within
limits) by changing the 1X, 16X, 64X clock devider rate.  i.e.
if you set the hardware switch to 1200 baud then by changing the
16X to 64X you would get 300 baud!  Hope this helps.
                                                       --Paul