[wk_end]

Yeah, writes are ignored, and reads return garbage (no idea what).

I recommend using the BGB emulator - you can configure it to crash into a debugger whenever it detects an invalid VRAM access. Plus the debugger is insanely useful.

[posterboy]

and the screen is blanked i suppose. that would allow pritive pwm. has that been used? i would imagine that allows some nice fade effects or enhanced bit-depth in the brightness, as is done eg. on c64.