A host device divides original data into first to Nth stream data for N being an integer of two or more, generates first to Nth compressed stream data by sequentially compressing the first to Nth stream data with a variable length compression, divides the first to Nth compressed stream data into fixed-length blocks, and sequentially transmits the fixed-length blocks to the display driver. The display driver includes a memory storing therein the fixed-length blocks and a decompression circuitry reading out the fixed-length blocks from the memory. The decompression circuitry includes first to Nth processing circuits. The first to Nth processing circuits each perform a predetermined process on the fixed-length blocks received to generate processed data. The host device sorts the fixed-length blocks so that the fixed-length blocks are supplied in the order in which the first to Nth processing circuits require the fixed-length blocks.