[hazeii]

I'm familiar with both, and have Pi's bit-banging at 8MHz. It's not hard-realtime like a PIC though (where I've bitbanged a resistor D2A hung off a dsPIC33 to 17.734475MHz). It's an improvement over the years, but surprisingly little since bit-banging 4MHz Z80's more than 4 decades ago, where resolution was 1 T state (250ns).

[londons_explore]

The 9 bit serial OP mentioned likely doesn't have a seperate clock line, so it is hard realtime and timing matters a lot, and I doubt the Pi could reliably do anything over 1 kHz baud with bit banging. You could do much better if you didn't run Linux.