A speaker has been implemented and now plays the square waves generated by the CPU.   I can tell by the sound and the pitch of it that it's not perfect, but it's something I'll work on.  The speaker is controlled by the CPU toggling one GPIO pin via the $c030 register.  Think of it as manual PWM.

I also added an on-screen menu display.  Not all menu items are implemented yet, but F1, F3 and F12 works.  Disk support is still in the works.

Just for fun, I tested the emulator with an Apple ][+ ROM today.  No compatibility issues, works like a dream.