I'm making a datalogger and need date and time. The data (20 bytes) will be stored at 1 second intervals and I need to keep 7 days worth of information. The system will only be on approximately 1/3 of the day.

First question, would a 256KB EEPROM be sufficient for this? I may be misunderstanding it but you can write 256KB a million times? Is that pretty much how it works?

The other question is regarding a RTC. Would DT's INT program work as a RTC with calendar? Seems to me that the hardest part would be keeping track of the date, not the time. Just looking for the easiest (not necessarily the one that costs the least) method to do this.