Changes
/* PPI */
In some emulators, keyboard is mapped directly behind PIO.
In original schematic, PIO is the only one component having a low state reset (0), I think that imply a 0 value as state init of internal components variable. Data bus of Z80 seems having a pull-up state (read 1 when nothing is plugged), for example a unplugged ROM does respond xFF in data-bus.
==== PPI: Yamaha clock ====
Overclocked at 16MHz.
==== PPI: arnoldemu testbench ====
arnoldemu's testbench PPI passed.
=== SOUND ===
PWM.
