Usage in [[Dk'tronics Real Time Clock]]:
Uses a Z80 PIO chip to control the HD146818 RTC chipvia port A. Do not use Port A as this will affect the RTC operation.
FBE0h Dk'tronics Real Time Clock - Z80 PIO Port A Data (HD146818P RTC Data bus)
FBE1h Dk'tronics Real Time Clock - Z80 PIO Port B Data, used for external control (General Purpose 8bit I/O Port)
FBE3h Dk'tronics Real Time Clock - Z80 PIO Port B Control
FBE8h Dk'tronics Real Time Clock - Control port for RTC chip (4bit latch) (details unknown)
Do not use Port A as this will affect B is connected directly to a standard 9-way connector on the RTC operationleft of the interface.
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