Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!rutgers!sri-spam!ames!elroy!mahendo!jplgodo!wlbr!pete From: pete@wlbr.UUCP Newsgroups: comp.sys.m6809 Subject: Re: rs232 Needed Message-ID: <1153@wlbr.EATON.COM> Date: Mon, 7-Dec-87 13:38:49 EST Article-I.D.: wlbr.1153 Posted: Mon Dec 7 13:38:49 1987 Date-Received: Sat, 12-Dec-87 16:29:58 EST References: <15741@watmath.waterloo.edu> <3986@pucc.Princeton.EDU> Reply-To: pete@wlbr.UUCP (0000-Pete Lyall) Organization: Eaton IMS, Westlake Village, CA Lines: 31 In article <3986@pucc.Princeton.EDU> EWTILENI@pucc.Princeton.EDU writes: >> I have COCO 3 128k > >That says it all right there. You DO NOT need an RS-232 Pak, then. > >The CoCo 3 can EASILY run 1200 baud out of the bitbanger port on the back >of the computer, using halfway decent software, and if you have a well >written program, it can do 2400 baud full duplex WITHOUT using the RS232 >Program pak. > >BITNET:ewtileni@pucc | ARPA:ewtileni@pucc.Princeton.EDU | ColorVenture | Wrong. Unless you wish to program the interval timer and poll the bit banger (highly unsatisfactory, unless you are single-tasking) at the designated intervals, it doesn't work worth a hoot. Reason: the idiotic engineers set up the interrupt generation logic on the receive data line so that an interrupt is kicked off on the *rising* edge. This is directly opposite of the way a serial (asynch) character is normally signalled.. that is, with a start bit (low - falling edge). Now, if you want to clip that inverter out of the circuit and spend some time rewriting SIO *then* serial port operations out of the bit banger could be satisfactory, but will still be more cpu-expensive than the RS-232 pak, or equivalent. -- Pete Lyall (OS9 Users Group V.P.) Eaton Corporation (818)-706-5693 Compuserve: 76703,4230 (OS9 Sysop) OS9 (home): (805)-985-0632 (24hr./1200 baud) Usenet: {trwrb,scgvaxd,ihnp4,voder,vortex}!wlbr!pete or pete@wlbr.eaton.com