I have one smartwatch installed under the BIOS EPROM on a Flytek motherboard (STJUKO TURBO Motherboard)
Please also look on my thread:
http://www.vintage-computer.com/vcforum/showthread.php?29091-Rtc-module-on-serial-com3-port
More detailed info:
http://www.brutman.com/PCjr/DS1216E.html
1.you need to pick the ROM chip
that responds to memory accesses at F000:000 (mostly the bios rom, not always!)
2. Download the software:
http://www.brutman.com/PCjr/downloads/ds1216e.zip
3. Run program TEST-CLOCK.EXE to verify if the clock is working and programmable..
4. Run CLOCK.EXE EVERY TIME you boots / reboots the system.. Better is to set a line in autoexec.bat..
5. With CLOCK.EXE you also can set the date and time and day...
The clock is only working when loading CLOCK.EXE on boot..
How to set it, just read the included manual / documents..
The good of this dallas solution..
Its working fine, and Y2K is supported up to 2099 or so..
No ISA card with clock needed (mostly they are dead, or doesnt support Y2K..)
Only a little bad is.. Older system diagnostics doesnt detecting this dallas..
The other good is, its just ****ing working under compaq DOS 3.31 !!
I think you wont find a better solution than this..