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Path: utzoo!linus!philabs!cmcl2!seismo!harvard!think!absolut!bill
From: bill@absolut.UUCP
Newsgroups: net.micro.pc
Subject: Re: Need help with AT RS-232!!!
Message-ID: <12000015@absolut.UUCP>
Date: Sat, 10-Aug-85 17:05:00 EDT
Article-I.D.: absolut.12000015
Posted: Sat Aug 10 17:05:00 1985
Date-Received: Wed, 14-Aug-85 03:15:16 EDT
References: <10000013@unido.UUCP>
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Nf-ID: #R:unido:10000013:absolut:12000015:000:1379
Nf-From: absolut!bill    Aug 10 17:05:00 1985




***** absolut:net.micro.pc / unido!vr0z05 / 12:06 am  Aug  8, 1985


>Also I have realized that the programming of the RS-232 interface must
>be a little bit different to the former XT. But I couldn't find out
>what has changed. A testprogram which shortens input and output of the
>RS-232 via the Modem Control Register (Bit 4 in $3FC set) and that ran
>correct on the XT doesn't do anything on the AT. I can send a character,
>I'm able to receive him via polling, the 8250 (is it really a 8250???)
>produces an interrupt ($04 in $3FA), but the processor never receives the
>interrupt, though I have set Bit 3 in the Modem Control Register (for OUT2)
>and Bit 4 on Port $21 (the 8259, again: is there a 8259 in the AT???) in 
>order to allow interrupts. What is wrong.
>
>				   Please help!!!
>				   Many thanks in advance.
----------
The following are the pinouts for the PC-AT Serial Port

1=Carrier Detect
2=Receive Data
3=Transmit Data
4=Data Terminal Ready
5=Signal Ground
6=Request to Send
8=Clear to send
9=Ring Indicator
The above are for the 9 pin DB connector
Source = uucp network

According to the PC Xenix manual the AT is configured as a DTE.
Hope this helps.

Bill

William Gibbs             {ucbvax!cbosgd!ima!cfib}\
46 Bryon Rd. Apt 5                                  !absolut!atgibbs!bill
Chestnut Hill, MA 02167               {decvax!cca}/
(617) 325-7482