Test program for simultaneous reading of the DMEM. A random test pattern is initialy stored in the
 all DMEM lockations by cpu3 via local bus. Then cpu3 reinitialize the pseudorandom generator
 to obtain the same pseudorandom sequence of test pattern
and copy the current data to grf[3].
   All cpus simultaneously read the same location of the DMEM and compare
 the result with grf[3]. The errors occured are accumulated and stored in DBANK at address 0xF00n
 for cpu(n).