A year ago I found a good replacement for a Dallas DS1287, the ALT12887. Used it on several Atari Falcon machines.
DS12887 substitute with replaceable battery.
– 1x DS12885/BQ3285 in SOIC package
– 1x 32.768kHz crystal, SMD, 6pF
– 1x CR1220 battery holder (Harwin S8411-45R or equivalent)
I just ordered a new set of PCB’s, I can provide you with a assembled version. Use my contact form to contact me.