A document scanning apparatus which is capable of scanning an oversized document. The fiber reinforced cementitious material includes a conventional cementitious material and less than 5 pounds per cubic yard of the cementitious material of fibers dispersed therein. Each memory block has a local power line, a plurality of functional circuits coupled to the local power lines and a voltage control device coupled between the global power line and the local power line. Arranged adjacent to the reaction member is at least one volume take-up means into which part of the reaction member may be displaced in the event of the vacuum servo brake being actuated.