Not sure if this is useful info .... I'll throw it out there for the archives ;-) Both the RTCs on my 9105FT and 9100FT went bad not long after I got them. The original is a Dallas 1287 (same as the IBM PC). It is a discontinued part. I bought a pair of 12887As from eBay which is a commonly used modern day "replacement". The 12887 has two banks of addressable memory (128 bytes vs 64 in the 1287) and the A variant has a RAM clear pin. Anyhow, neither 12887A worked. The system would constantly report at boot that the RTC battery needed replacement, this seems to occur when the 9100 reads null (epoch) data from the RTC. The 9100 is able to tell if it's a new chip as at first boot it instead reports that the RTC is uninitialized. I was floating the RAM clear (per datasheet), so my guess is the second bank was the issue. So it's possible a 1287A would have worked. There is an appnote #503 from Maxim addressing this issue of possible incompatibility. Anyhow, I purchased two 1287s from eBay (china). I was a bit worried about a fake as it's an obsolete chip but they both worked fine. There is also a tutorial out there on breaking open the 1287 packaging and adding an external piggybacked battery. I just desoldered and socketed and went for a replacement chip. HTH Tony _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com https://pairlist7.pair.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/