Watford Electronics DDFS V1.40 (1984)(A.C. Bray)
Watford Electronics DDFS V1.53 (1985)(A.C. Bray)
Watford Electronics DDFS+ V0.91 (1985)(A.C. Bray)
Watford Electronics DDFS V1.54T (1987)(A.C. Bray)
Watford Electronics DFS V1.30 (1983)(A.C. Bray)[a]
Watford Electronics DFS V1.44 (1986)(A.C. Bray)[a]