Electronic printer apparatus in which the intensity of the beam of a cathode-ray tube (18) is controlled during successive beam sweeps to display and project onto a rotating electrostatically-charged surface (14) an image of successive slices through a row of characters to be printed, the latent line images thus formed being then converted (at 22) to a toner image for subsequent transfer to a page of paper (from 38). Digital information bits organized in bytes and representing slices through each character are stored in respective areas of a permanent memory storage device. The appropriate slices of the characters are accessed in response to character-representing input signals, and are read out serially to control the beam intensity during each sweep and thus display, along the sween the desired slice through the stored bits for each character slice are organized into various integral numbers of x-bit and y-bit bytes, preferably 8-bit and 6-bit bytes, the number of bytes of each type for each character slice depending on the bit width of the corresponding character cell; there are no extra or left-over bits beyond these included in the two types of bytes. The so-stored bytes of differing bit content are accessed byte-by-byte, enabling simplification and reduced cost of the apparatus.