if this is in response to the other post then inverted TTL is the output from a microcontroller for controlling serial devices, so when something is sent from the controller to the recieving device - the signal is the opposite of what a full RS232 serial device would show - eg a '1' on RS232 is actually -12v, and a '0' is +12v, although if you are dealing with inverted TTL in this sense a '1' is +5v and a '0' is 0v - This is the way that many serial devices work to negate the effect of having to use MAX232 ect. to provide the +12v and -12v for full RS232 spec.
I hope that makes sense to you :?