Contains a rechargeable battery, five chips, a quartz crystal, and a few odds and ends. The RTC chip is a HD146818 (which is also used in IBM PCs).
Info Fragment
Reportedly: DK-Tronics RTC module used a Z80-PIO chip to address the RTC itself as Port A of the PIO, with a 9-pin user i/o port as Port B.
I/O Ports
FBE0..FBE3 Dk'tronics Real Time Clock FBE8 Dk'tronics Real Time Clock
