Probably most of you (if not all) use more modern SPI/I2C based
RTC chips these days. However, for those who might me interested,
I publish the way to attach mux-bus based RTC chip (e.g: DS1685/1687,
Intel 8051 type of architecture with ALE strobe pin to latch multiplexed data/address)
to the non-multiplexed (separate) parallel addr/data bus system (like 6502).

Details are here:

http://6502cpu.blogspot.com/2012/01/mkh ... 85-or.html

Bottom line: Don't be tempted to synchronize /WR and /RD signals with
PHI2 signal. That IC does not like it and the timing will not be right.
It is OK to synchronize chip select signal with PHI2.

Cheers!

_________________
Marek Karcz
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"Don't worry. We've got our best people working on it."