After determining requirements, Wooddell examined possible hardware and software tradeoffs. In an insightful memorandum, John Morecroft explained the concept of "soft logic" as a complement to the "hard logic" in the Flight Data System44. Writing in 1975, when the actual flight software began to be prepared, Morecroft pointed out that the program for the computer was actually a soft representation of hard-wired circuits. Conceptually, the memo stands as an explanation of the essential meaning of firmware in general.
Looks like this, although a quick search doesn’t find it:
43. J. Wooddell, "Design of a CMOS Processor," pp. 2-3, files of J. Wooddell. 44)J. Morecroft to K. Frewing, "FDS Programming," January 14, 1975, files of R.J. Rice, Jet Propulsion Lab.
