Re: What is the quintessential Apple II?

["Michael J. Mahon" <mjmahon@aol.com>]

Dave Althoff, Jr. wrote:
> Michael J. Mahon <mjmahon@aol.com> wrote:
> : Roger Johnstone wrote:
> : > 
> : > We made a new board with a single 8-pin micro on it which performed both 
> : > functions. The resistor for the variable time is read by the micro 
> : > charging up a capacitor, then timing how long it takes to discharge it 
> : > through the resistor. I'm surprised no-one thought of doing that before ;
> : > o)
> : 
> : Yes, that's a favorite trick for cheap analog input.
>
> I hope you understand the significance of...I guess it was Roger's 
> comment, including the "I'm surprised no-one thought of doing that before 
> ;o)", and *exactly* why he said it...
>
> I've been away from here for a while, so I don't know what the 'apple ][ 
> geek quotient' of the current population is.  But that is exactly how the 
> Apple ][ paddle inputs work, discharging an onboard cap through a 150-ohm 
> pot in the paddle...

It's 150k ohms, but I thought his "no-one thought of doing that before"
applied to the particular microcontroller application he was discussing.

It's an old trick, and I'm sure the Apple II wasn't the first to use it.

-michael

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