PC-98’s video mode are 15.98kHz, 24.83kHz, and 31.5kHz(PC/AT compatible).
Usually, 640x400 24.83kHz mode is used.
For games that need speed, it will use 640x200 15.98kHz mode.
Perhaps there is a shortage in drawing in 24.83kHz mode.
I’ll seek it.
Image distortion happen when GDC clock is on 5Mhz
You are right.
By the way, I used X68k longer than PC-98…