Serial Output logic inversion?

I used to know this, but I have forgotten.

To connect the serial output (TX) from a PIC that has a USART to the SerialDataIn Pin of a computer's serial port requires a logic inversion, right? That is normally provided in a MAX232, which also provides negative level shift.

AFAICR, I have done this before with nothing but a simple inverter operating between 0V and 5V. I know that the RS232 spec expects the logic level to swing below 0V, but it seems to work ok even if it doesn't.

Yes it needs to be inverted.

If you need a hardware inverter solution you can use a NPN transistor (as open-collector) with a pullup resistor on it's collector.

Mike K8LH posted a simple version a while ago. Clicky.

Mike.