As early as November 1962, the possibility of purchasing a microfilm recorder was raised with the Atlas Computer Committee. As well as being useful for bulk printed output (especially as out put was to be delivered back to users via the postal system), The Committee also saw the potential for using it both for graphical output and animation. Shock wave propagation was seen as a potential application for animation.
The case got put on a back burner while Atlas was commissioned and there was also some discussion of attaching an interactive display to Atlas. The discussion of the purchase of a microfilm recorder resumed in April 1966 when the Committee noted that consideration was being given to the acquisition of a microfilm recorder. The choice seemed to lie between a Stromberg Carlson 4020 (purchase price £86,000) and a similar recently developed device of Benson-Lehner (purchase price £53,000). Formal proposals would be put to the Committee at its next meeting.
Formal approval to purchase an SC4020 came in January 1967 at a cost of approximately £70,000.
Several of the Atlas staff already had experience of using an SC4020. A machine had been installed at Aldermaston in 1962 and Bob Hopgood was working there on the S2 Fortran Compiler at the time including checking the correct working of some Fortran animation films. Paul Nelson established a service from Harwell to the Aldermaston machine some time in 1963.
Paul had put a lot of effort into making the case for the SC4020 prior to its purchase. Paul and Bob were the main people involved in establishing access to the machine early on with Paul concentrating on the Fortran users and Bob the Algol ones.
