- there are several (sub-)modes and protocols in which the interface can operate?
- there is an easy DIY possibility for a PC-USB connection cable with FULL RTS/CTS hardware handshake?
- it can be used as a hardware controller, like an Arduino but with an integrated dev env?
- there is a full PIC-microcontroller dev env, including a PIC-burner algorithm? (but how does it work and what kind of burning hardware is needed?)
- how it is possible to operate the 4-color plotter CE-515/6P?
- there are 2 different synchronous, serial protocols (one beiing for the CE-126P)
- there is an API for writing custom serial protocols?
- BSAVE/BLOAD can be used to store programs on tape via the CE-126P and for interchange with another PC-G850V(S)?
So I decided to trace it down and write a hopefully consistent doc. Here I share it with the community.
The original text was written in German and forms "Anhang A" of Jörg's very nice project "SHARP PC-G850V(S) Benutzerhandbuch"
SHARP PC-G850V(S) Bedienungsanleitung (german)
To reach a broader audience, we both think the whole manual should be translated into english!
I make a start with my chapter about the 11-pin interface, which you can download here (I'm not a native english speaker though

SHARP PC-G850V(S) - An In Depth Doc of the 11-Pin Interface (english)
I tried to verify all the bits and pieces and to provide sound, self contained examples.
Have fun reading - comments/additions/corrections welcome.
Cheers
Tom
[EDIT: BSAVE/BLOAD pulse width modulation mode added]