BRIEF DESCRIPTION OF THE DRAWINGS One multiprocessor computer system in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, of which: FIG. I is a schematic block diagram of the system; FIG. 2 is a schematic block diagram of a fault channel of the system; FIGS. 3, 4 and 5 are circuit diagrams showing parts of the fault channel in grea