On the 747, 80 knots is the low speed decision to abort for any EICAS message. Above 80 the only reason to abort is the usual engine failure, unsafe to fly decision before V1. Above 50 knots the A/T goes from THR REF to HOLD were the auto throttle servos are inhibited. This aunnunciates around 70 knots. With the average VMCG around 118 knots a 100 knot check would seem a little late in my opinion. From memory both the 737 and the 727 also had the 80 knot call.