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From: jhs@MITRE-BEDFORD.ARPA.UUCP
Newsgroups: comp.sys.atari.8bit
Subject: Controlling a robot with an 800...
Message-ID: <8701261739.AA17227@mitre-bedford.ARPA>
Date: Mon, 26-Jan-87 12:39:50 EST
Article-I.D.: mitre-be.8701261739.AA17227
Posted: Mon Jan 26 12:39:50 1987
Date-Received: Tue, 27-Jan-87 06:30:32 EST
References: <12273590292.14.G.ABRAMS@Score.Stanford.EDU>
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I would suggest that you consider using the joystick ports to output commands
to the robot as an alternative.  I think on an 800 $D301 controls the 3rd and
4th joystick outputs, which have 4 bits of output each.

On the 850 interface, you are talking over the serial bus, so it is not just
a question of POKEing into an address.  I think you can send commands by
pretending it is the P: device (parallel printer) that you are talking to.
However, you may have some trouble with its wanting to buffer up a whole line
of data at a time.  You may have to be careful how you OPEN the channel to
the P: device.  You should read up on the XIO command and read the 850 user
manual carefully.

Using the joystick ports 3 and 4 you are talking to a PIA so it is a true
parallel output situation.  You will not have to worry about any "helpful"
buffering of the commands you send out.  Also, this will leave the P: port
free to run a Centronics-type printer if you so desire.

Good luck.

-John Sangster
jhs@mitre-bedford.arpa

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