a substrate containing wiring traces for conducting signals;

first contact pads along a first edge of the substrate, the first contact pads for mating with a memory module socket on a motherboard;

a test socket, mounted to the substrate, for receiving a memory module during testing and programming;

wherein the wiring traces on the substrate include lines carrying address, data, and controls signals from the motherboard that are passed through to the test socket at pads for connecting to memory chips on the memory module;

wherein the memory chips on the memory module include a plurality of data memory chips for storing user data from the motherboard, and an error-correction code (ECC) memory chip for storing correction code generated by a code generator on the motherboard, the correction code being a pre-defined function of the user data;

wherein the wiring traces on the substrate include a plurality of first data lines and a plurality of second data lines that carry the user data from the motherboard, and a plurality of ECC lines that carry the correction code from the motherboard;

wherein the test socket includes first contacts and second contacts that connect to the memory chips on the memory module inserted into the test socket, and ECC contacts that connect to the ECC memory chip on the memory module inserted into the test socket;

wherein the plurality of first data lines connect to the first contacts in the test socket to connect to memory chips on the memory module inserted into the test socket; and

cross-over means, on the substrate, for connecting the second data lines to the ECC contacts in the test socket and for connecting the ECC lines to the second contacts of the test socket during an ECC test mode;

wherein user data containing test patterns are written to the ECC memory chip through the cross-over means during the ECC test mode, while the correction code from the motherboard is written to one of the memory chips connected to the second contacts in the test socket.