A structure comprises a single wafer with a first subcollector formed in a first region having a first thickness and a second subcollector formed in a second region having a second thickness, different from the first thickness. The CD is controlled, at least in part, by a processor IC according to a software program operating therein and provides feedback to a user via a visual display, an audio alarm, and a vibrational alarm, and allows input from the user via a touch sensitive keypad. The image forming apparatus further includes a second positioning member which engages with the first positioning member. If they are the same, the primary system backs up the corresponding block by simply informing the backup system of the matching content, and having the backup system write the matching content of other backup block over the respective backup block, rather than transferring the entire block contents.