Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!caen!rphroy!rcsrlh!rhaar
From: rhaar@rcsrlh.GMR.COM (Bob Haar CS50)
Newsgroups: sci.electronics
Subject: Re: AMD 8251 (USART) Info?
Message-ID: <37880@rphroy.UUCP>
Date: 13 Nov 90 20:09:59 GMT
References: <60822@bbn.BBN.COM>
Sender: news@rphroy.UUCP
Reply-To: rhaar@rcsrlh.GMR.COM (Bob Haar CS50)
Lines: 18

In article <60822@bbn.BBN.COM>, gonzalez@bbn.com (Jim Gonzalez) writes:
|> 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. 

I am not familiar with the Cromemco system 3 board, but try to get a
listing of it's bus signals. Many of the 4 and 6 MHz Z-80 CPU boards
for S-100 systems used one of the "unassigned" pins for an alternate clock.
This is because many peripheral cards needed a 2 MHz clock. If there is
one, just jumper the clock input to that bus pin.

	Bob Haar   CSNET: HAAR@GMR.COM  UUCP: uunet!edsews!rphroy!rcsrlh!rhaar
	Computer Science Dept., G.M. Research Laboratories
DISCLAIMER: Unless indicated otherwise, everything in this note is
personal opinion, not an official statement of General Motors Corp.