A compact interface unit for use with a scanning plasma display, has a random access memory unit for storing representation of characters to be displayed, and apparatus for cyclically energizing the dots of the matrix. New character codes are written into the random access memory unit during the time the dots of the display unit are energized. A column counter specifies which of the 5 columns is to be read out at any given time, and character generator ROM'S are provided to read out a 5.times.7 dot matrix for selected characters on a column-by-column basis, and a parallel-to-series counter unit converted to the ROM'S provide a serial data stream corresponding to the same dot column of characters in multiple rows. Two serial-to-parallel converters are provided for separating the serial data stream into control signals for controlling the energization of the rows of dots of the matrix unit. In the preferred embodiment, the interface is mounted on the back of the display device. The total depth of the interface is one and one-half inches.