[Coco] Floating bit banger input on CoCo 3

[Darren A]

Is it normal for the CoCo 3's bit banger input circuitry to indicate
SPACE when no cable is connected?  I had always assumed that it would
indicate MARK just like a CoCo 1 or 2, but that doesn't appear to be
the case with my CoCo 3.

If anyone would like to try a test, doing a PRINT PEEK (65314) will
return an even number for SPACE or an odd number for MARK.

Darren