Kitty Chan:
Wow you are throwing around lots of part numbers there. Note that the DS1225 is not an EEPROM. This chip was/is a non-volatile SRAM (i.e. SRAM chip with battery attached).

The 2864 is an EEPROM however the 2764 is an EPROM. The difference being that the first is electrically erasable and the second is erased upon exposure to ultraviolet light of the proper range of wavelengths.

It is rather hard to suggest possibilities of relacements for these when all three parts are different technologies and may be used in the circuits in different ways. There are cases, completely dependent upon the application, where these parts may be used as partial substitutes of each other.

Your best bet is to first understand the application where you need the replacement part. How is the part used, how does it get its data into it, is it programmed in-curcuit, etc etc .... Next find data sheets for the possible replacements and read the functions and specifications and see if the replacement part will perform the functions required in the original circuit.

Good Luck...
Mike Karas