> Thank you very much for your help!  The main reason why I
> want to use this IC (DS17287) was I need more RAM space
> (about 2K bytes or so).  I only have enough I/O on the
> PIC18F452 to interface to a "8-bit multiplex bus" RAM chip.

Not only Maxim makes RTC's.
IMHO, this is an nice chip :

http://www.ramtron.com/doc/Products/Products_detail.asp?ID=15&FamID=2

Or the data sheet directly :

http://www.ramtron.com/lib/literature/FM31xx_r0.21.pdf


You get :

- Serial Nonvolatile Memory (from 512 bytes to 32 Kbytes)
- Real-time Clock (RTC)
- Low Voltage Reset
- Watchdog Timer
- Early Power-Fail Warning/NMI
- Two 16-bit Event Counters
- Serial Number with Write-lock for Security
- Programmable VDD Reset Trip Point
- Manual Reset Filtered and De-bounced
- Programmable Watchdog Timer
- Dual Battery-backed Event Counter Tracks

Saves you I/O and gives you more RAM...

Regards
Jan-Erik Svderholm

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