Williams(ID:6501/wil002)

Proto-index register for the Manchester Copmuter 

B-tube system for Manchester University computer. So-called because "the letters A and C had already been used up" (ie the A-tube (accumulator) and C-tube (control))  

This tube stored modifiable instructions, which ultimately became index registers, and were hugely influential when Williams told the IBM engineers at Poughkeepsie about it in August 1949, and were incorporated into the IBM 701 (which in turn made Speedcoding possible)
Related languages
Williams => SPEEDCODING   Influence
References:
  • "The Speedcoding Language and interpreter" 9.3 pp333-338 view details
          in C.J. Bashe, L.R. Johnson, J.H. Palmer, and E.W. Pugh "IBM's Early Computers" MIT Press, 1986 (Vol. 3 in the History of Computing series) view details