** A expansion device (e.g. a ROM-board) can use this signal to activate the selected ROM plugged into the device.
* Sound (Mono Audio; Output from PSG). This is a mono audio signal generated by mixing the 3 PSG audio channels together.
* /WAIT (Ready / Wait; Input to CPU, Output from Gate-Array). When /WAIT="0" this signal is used to delay memory or I/O access by the CPU. This signal is used to force the CPU to access memory or I/O when it is ready. This signal is generated by the Gate-Array.
* /WR (Write; Output from CPU). When /WR="0" the CPU is performing a write operation. The operations are:
** Writing to a I/O device: (/IORQ="0", A15-A0 contain I/O address)