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From: cdold@starfish.Convergent.COM (Clarence Dold)
Newsgroups: comp.sys.ibm.pc,comp.periphs
Subject: Re: Using a Joystick instead of a Mouse
Message-ID: <624@starfish.Convergent.COM>
Date: 9 Aug 88 16:44:05 GMT
References: <6255@chinet.chi.il.us>
Organization: Convergent Technologies, San Jose, CA
Lines: 32

>>Have any of you plugged an Atari joystick into the serial port and used it
>>instead of a mouse?  Doing so would make playing some games easier.
> All that I need a joystick for is to _indicate direction_.  If I manage to
> interface a joystick to my Toshiba laptop, I will write custom software to

Oh, now I understand...
A REAL computer hobbyist, just like in the old days!
Since the Atari joystick has four switches that close to a common pin,
you need to either use an ohmeter to find the pin shorting relationship, or
wait for me to blow the dust off my ATARI 400 Tech Ref.
Next, make an adapter cable that will couple the common pin to DTR on the 
serial port.  Then tie your choice of the direction pins to CD, DSR, RI, and
CTS on the serial port.  A program can drive DTR high, then monitor for
combinations of the status lines to see which way the stick is pointed.
A hardware purist might ask for resistors in the adapter cable, but they aren't necessary.
This is the method I use to interface a small UPS into my *IX system,
for Powerfail shutdown.


SIGNAL		PC-XT		PC-AT
		Female		Female
	DIR	25 pin		9 Pin
	
TX	<-	2	-	3
RX	->	3	-	2
RTS	<-	4	-	7
CTS	->	5	-	8
DSR	->	6	-	6
GND	--	7	-	5
CD	->	8	-	1
DTR	<-	20	-	4
RI	->	22	-	9