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From: @purdue.ARPA:mjs@purdue-ecn-ee.ARPA (mjs)
Newsgroups: net.micro.cpm
Subject: Re:  8251 Usart
Message-ID: <1110@brl-tgr.ARPA>
Date: Mon, 30-Dec-85 12:43:10 EST
Article-I.D.: brl-tgr.1110
Posted: Mon Dec 30 12:43:10 1985
Date-Received: Wed, 1-Jan-86 00:56:54 EST
Sender: news@brl-tgr.ARPA
Lines: 34

Thanks for your quick reply.  First of all, let me give you a little 
background about this computer(Royal Alphatronic PC).  According to Royal,
the only way to change the baud rate is by a hardwired jumper on the 
main PCB.  But, like I said, I've been able to change it as long as I
don't try to send data out. When I send something out, everything locks
up and I must do a cold boot.  This mystifies me, because everything that
I am doing seems to make sense.  Here's my setbaud.asm:


MCNTR	EQU	41H		;Modem control port
RESET	EQU	01000000B	;Value for port reset
MINIT1	EQU	01111010B	;Value for 1 stop bit, even parity,
                                ; 7 data bits, 16X baud rate
MINIT2	EQU	00010101B	;Value for Error reset, transmit 
                                ;enable, receive enable

	ORG	100H

INITIALISE:	MVI	A,RESET 	;Puts 8251 in instruction mode
		OUT	MCNTR		;
		MVI	A,MINIT1	;sets up baud, etc.
		OUT	MCNTR		;
		MVI	A,MINIT2	;Puts 8251 back in normal mode
		OUT	MCNTR
		JMP	0

This is pretty self explanatory, I guess... and it SHOULD work, but
there must be something that I'm missing... 

Let me know what you can come up with.

                                   Thanks again,
                                   Mike
                                            ihnp4!pur-ee!mjs