On Tue, 28 Sep 1999, Grey Wolf wrote:

> On Tue, 28 Sep 1999, John Refling wrote:
> 
> # 
> # >> discussion on adding a resistor on the RX line to pull voltage down
> # >> to -10 volts, when inactive.........  proposed
> 
> Just a minor nit:  I thought voltages for RS232 were supposed to be
> between 0 and 5, since RS232 originally ran on TTL.

Nope, a bit-0 is a positive voltage, and a bit-1 is a negative voltage.
positive and negative voltages are from 3 to (I think) 25 volts. Also
don't forget that, back in the day when this was developed, logic boards
commonally had -5 V and some 12 V volatages around. :-)

Take care,

Bill