Figure 1a shows the RCS screen for configuring the I/O subsystem, and the processing and control units. The I/O subsystem can contain up to four DMA controllers, denoted as DMA1.x. The subsystem can contain eight peripheral device controllers, denoted as KP1.xand KP2.x, in which x= 1,…,4. Each controller can be disconnected or reconnected by consecutive mouse clicks on the appropriate box.