Many vintage systems from the late 80s and early 90s will use a dedicated RTC chip in order to maintain system time and storage of some settings. One of the most popular RTC chips of this era was the venerable Dallas DS12887.
However, these RTC chips included a built-in and – importantly – non-replaceable battery, meaning that if you find one of these chips still in use today, it is all but guaranteed to no longer function without custom modification.
The SB1287 is a drop-in replacement for these RTC chips. Utilising an original Dallas DS12885 clock chip, the SB1287 is directly compatible with all DS12887 and DS1287 chips in use, and should also be compatible where an existing DS12885 or DS1285 are in use. It should also be a drop in compatible replacement for MC146818 in some systems, but this has yet to be thoroughly tested.
It keeps memory using a standard CR1220/CR1225 coin cell which is inserted into a battery holder on top of the board, and a CR1225 cell is included with purchase to get you started immediately.
Designed, assembled and tested in Sydney, Australia!