RANDOM: MOVE A,HI ;register A gets loaded with "high" word MOVE B,LO ;register B gets loaded with "low" word MOVEM A,LO ;register A gets stored in "low" word LSHC A,35. ;shift the 72-bit register AB left 35 XORB A,HI ;bitwise exclusive-or of A and HI replaces both[PDP-10 Info]
This suggests a susceptibility to analysis of mechanical code machines.
See LOOP DETECTOR item in FLOWS AND ITERATED FUNCTIONS section.