A device for accessing a ROM unit with groups of module information of memory modules saved therein. This invention saves plural groups of memory module information in a ROM unit, and applies a selecting circuit to indicate a memory module information to be loaded out. In an embodiment, the selecting circuit has a voltage divider circuit driven by the WP Pin of an IC, and a comparer or a converter to connect with the voltage divider circuit so as to produce a selecting signal, and then uses a decoder to transfer the selecting signal into a address number which will be used to read the selected memory module information from the ROM unit. In another embodiment, the selecting circuit has a plurality of fuses which are connected with plural output-pins of an IC, and multiplexers to optionally disconnect some fuses of the fuse circuit so as to generate kinds of different selecting signals. The selecting signals will then be decoded to locate the required memory module information from the ROM unit.