 Opcodes were 6 bits, registers 3 bits, index register (modifier) 2 bits and data address 13 bits.Shortly after the cancellation of the Blue Envoy in 1957, an emergency meeting between the primary contractors, Ferranti and Bristol Aerospace, led to the idea of combining components of the Blue Envoy with the existing Bristol Bloodhound to produce a much more capable design.This produced the Bloodhound Mark II, roughly doubling the range to about and using the new radar systems from the Envoy which allowed the missile to track targets much closer to the ground and was much more resistant to radar jamming.