Abstract: An device for programming and reading codes onto an array of binary data storage element includes: a shift register for receiving, sequentially, a binary data series to be written onto the data storage elements; and control logic circuit for determining whether or not data is to be applied to each of the data storage elements in turn, by reading sequentially the data stored in the shift register and if it is determined that data is to be stored on a respective data element, applying a write signal to that data element. The control logic circuit applies a permanent locking signal to the array of data storage elements such that further writing to the elements is prohibited when it has been determined that data has been written to each of the elements which require data to be written thereto.