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)'''
The battery is charged while the computer is switched on. The data will be retained for several months even if the computer is not used during this time.
PIO Port A seems to be the plain RTC Data Bus, there should be also RTC Read and Write signals, which are maybe found in the '''(details unknown)''' port?