The storage components of the FIFO buffer 44 are registers 52 arranged as a shift register series 53.Since the total number of valid outputs may vary due to the differing rates of storage and access, the bus 51 is connected to each register 52.An increment/decrement counter 54 is used to count the occurrences of FIFO buffer 44 writes and FIFO buffer 44 reads.Counter 54 has access to the pixel clock CP and a FIFO read signal SR.