Changes
Don't forget to use RETN for NMI handlers as well as RETI for normal interrupt handlers. In other case, the Z80 CPU will not
aknowledge the next interrupt properly.
==Audio Channels==
===Informations===
The CTC-AY board is populated with two AY compatible soundchips, adding 6 stereo channels. The YMZ294 eliminate the I/O port
and improve the CPU interface through /CS, /WR control signals and a 8-bit data bus. Each sound chip can be directly
programmed using two dedicated I/O ports for registers and data. No initialization code is required.
By default, the YMZs are clocked at 4 MHz but run internaly at 2 MHz. So, they will sound like an Atari ST, while you don't change
the frequency by reprograming the CTC Channel 0.
===YMZ294 Registers===
