I have published the QX-mini51 sample programs, converted to compile with SDCC instead of Keil, at a new Github repo, see the list of repos referenced by this project. They are fairly basic but demonstrate how to handle peripherals on the MCS51 architecture. I have also included some code::blocks project files if you want to use an IDE to develop. I'd be interested to hear from people using that. I only read about it and installed it recently.

Have a lot of fun.