Last week I soldered back the Ricoh RP5C01 and the D flip-flops which latch the 4-bit address bus.
I decided to power up the board halfway through, before reconnecting the RTC to its 32768 Hz quartz oscillator and the power supply circuit.
Surprisingly, the CPU was still able to write the date/time registers and read them back. Of course, the seconds wouldn't increment without a clock source!