[Coco] XPander-Coco lives!

RETRO Innovations go4retro at go4retro.com
Sun May 1 20:32:11 EDT 2016

On 5/1/2016 7:29 PM, Zippster wrote:
> Hi Gene,
> That internal pull up is on an input tho the MAX811 that can be used to drive it’s
> !RESET output low.
> That’s interesting about the cap in the CoCo’s reset circuit.  Something to keep in
> mind for sure.
> Jim, I just noticed in the data sheet, there was a page mentioning contention on the
> reset line with the MAX811 in case something else, an MCU in their example, wanted
> to pull it low.  They suggest a 4.7K series resistor on the reset line from the 811, which
> had occurred to me too.  Perhaps that would be enough.
> - Ed
That'd probably work (5/4700 = ~1mA, which should be easy to overcome 
with most logic families).

That said, the same SO23-3 footprint offers lots of options that only 
pull to ground.


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