Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: $Revision: 1.6.2.16 $; site absolut.UUCP 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> Lines: 42 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