[Coco] TTL levels and the bit banger port.

[Robert Gault]

Mark Ormond wrote:
> I was thinking of picking up some ft232r to uart boards and install them into my coco and my commodore.
>
> Now the serial i/o on the commodore is already +5 ttl levels, and I seem to remember that the coco bit banger port was rs232 compatible but not rs232 compliant(i.e. not +/- 12v). Does anyone know the voltages the bit banger port uses? Or is there a chip I could bypass to get to the TTL level signals?
>
> Thanks,
> Later,
> dabone
>

The service manual for the Coco3 indicates that the serial output is +-5vDC but 
the lines are protected so that an external voltage of +-12 won't blow anything. 
The RS232 input can handle +3 to +25 and -3 to -25 vDC.