Issue No. 01 - January (1976 vol. 9)
G.F. Casaglia , Ing. C. Olivetti & C. S.p.a.
Vertical microprogramming (or, as others say, functional microprogramming or firmware) was introduced in contrast with Wilkes' microprogramming (generally called horizontal or structural microprogramming), and has greatly enhanced the use of microprogramming in control design and implementation. As applied today, the former technique is not yet a way of designing control structures, but an additional software level whose implications in the system are not well clarified.
G.F. Casaglia, "Special Feature: Nanoprogramming vs. Microprogramming", Computer, vol. 9, no. , pp. 54-58, January 1976, doi:10.1109/C-M.1976.218388