Date   : Tue, 13 Nov 1990 18:50:29 GMT
From   : bbn.com!gonzalez@apple.com (Jim Gonzalez)
Subject: AMD 8251 (USART) Info?

I am in the process of getting a Northstar HSIO (serial interface) board
working on a Cromemco System Three (S-100 bus with a Z-80).  The CPU board
apparently produces a 4MHz clock, while the serial board expects to be 
clocked at 2MHz.  I could adjust the baud rate specification by a factor 
of 2 (yielding 1200 baud when I tell it to run at 600, for example), except
the 8251 is only rated to run up to 2.4MHz.  The 8251A is rated for a
maximum of 3MHz, so a chip upgrade won't help either.

Des anyone know if there is a faster version of the 8251 available?  My
information comes from the 1987 ediiton of an Advanced Micro Devices data
book.  The part must be a drop-in; if I have to do any cutting I may as 
well just build a new board.

                                       -Jim.