🚀 go-pugleaf

In article <1992Dec14.223424.21680@unlv.edu> bill@pauli.lv-physics.nevada.edu (Bill ODonnell) writes:
>
>     If extreme accuracy isn't a major concern you may
>want to consider using the game port on the Apple.  The
>Apple II series and the Apple IIGS both use a 4 channel
>A/D converter to read the voltage (via a variable resistor)
>at the game port.
>
(stuff deleted)

Sorry; that ain't correct.  The Apple ][ game ports work almost exactly
like the IBM game ports:  they use a 558 quad timer chip to generate 
time delays proportional to RC time constants.  The C is built into
the game port, the R is provided by the joystick or paddles' 
potentiometers.  The game ports can measure resistance, but not 
voltage.

I think that CoCo's have actual A/D converters on their game ports;
I don't know this for a fact, however. 

It is incredibly easy to interface some A/D converters to the
Apple ][ bus; some of the data sheets for Analog Devices converters
include complete details.  Offhand I think the AD7578 might be one
of those; maybe someone else who has the data sheets can confirm
this. 

regards,
--
Dave Angus                                   "Kundalini wants his hand back"