1. A method of testing a data storage device without revealing a memory content of the data storage device, comprising the steps of: a. reading a Current Value of a memory location in the data storage device, comprising a plurality of bits of data, b. writing a New Value into the same memory location in the data storage device according to the equation 
 New Value=Current Value XOR Data Seed where Data Seed is a value obtained from a data seed register, c. writing a copy of New Value into a data-written register, d. reading New Value out of the data storage device, e. comparing New Value read out of the data storage device in step d. to the corresponding New Value in the data-written register to verify the accuracy of the data read out of the data storage device in step d.