IIRC on CM-1/2 the LEDs reflected state of conditional execution of the individual VLSI packages (there is one LED per package, not one LED per CPU), on CM-5 it

IIRC on CM-1/2 the LEDs reflected state of conditional execution of the individual VLSI packages (there is one LED per package, not one LED per CPU), on CM-5 it is just a bunch of LED matrices controlled more or less globally by I assume some BMC-like thing.