Abstract: A programmable memory cycle is entered on a keyboard and set by a remote system control processor. Each local processor controls access to memory boards in accordance with the set memory cycle. When the memory cycle is divided into four memory access slots, the processor can provide, in each memory cycle, three read slots and one write slot, two read slots and two write slots, or one read slot and three write slots. When used for processing video signals, the arrangement can process three video channels, or more if expanded by the provision of further memory boards and local processors.