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Path: utzoo!decvax!decwrl!pyramid!hplabs!tektronix!reed!bart
From: bart@reed.UUCP
Newsgroups: net.micro.mac
Subject: Re: Mac serial port
Message-ID: <3930@reed.UUCP>
Date: Tue, 29-Jul-86 16:38:52 EDT
Article-I.D.: reed.3930
Posted: Tue Jul 29 16:38:52 1986
Date-Received: Thu, 31-Jul-86 00:22:08 EDT
References: <154@gt-eedsp.UUCP>
Distribution: na
Organization: Reed College, Portland, Oregon
Lines: 22

In article <154@gt-eedsp.UUCP> owen@gt-eedsp.UUCP (Owen Adair) writes:
> I am looking for info on how to initialize the serial port on the Macintosh
> for baud rates below 110 baud. Help!

{ take a baud rate (e.g. 50, 19200), and return the clock time constant }
{ analogous to the defined IM constants (e.g. baud19200).  This returns }
{ the same values as IM over the the set of IM defined constants.  This }
{ information is based on Zilog's Z8530 manual and the Hardware chapter }
{ of IM.  Note that the value for 56Kbaud is minimal, and that too low  }
{ a baud rate will return a value too large for the 16 bit counter in   }
{ the SCC.								}
function baudclock( baud : longint ) : integer;
const
	clockfreq = 3.672E6;	{ basic baud clock frequency in Hz }
	clockdiv = 16;		{ the SCC has been told to divide by this }
begin
	baudclock := round( ( clockfreq / ( 2 * clockdiv * baud ) ) - 2 );
end;


					Bart Massey
					UUCP: ..tektronix!reed!bart