Uses a Z80 PIO, MM58174 RTC, 6116 (2K RAM), 32.768kHz Crystal. Both RTC and RAM are backed by rechargeable 3.6V NiCad battery. Used I/O Ports are (with only A10,A4,A3 decoded):
FBE7 FBE7h ACU Real Time Clock Z80 -PIO Data In/Out Port A FBEF FBEFh ACU Real Time Clock Z80 -PIO Data In/Out Port B FBF7 FBF7h ACU Real Time Clock Z80 -PIO Configure Port A FBFF FBFFh ACU Real Time Clock Z80 -PIO Configure Port A
The 4bit RTC Registers are:
0 Not used / Test (W)