I can not remember me in detail because I made the conversion some years ago.
It exist a modified version of Nester called "NNNesteR" (not "NNNesterJ") which support 3 different tape extensions to save the data recorder file.

http://fs2.directupload.net/images/150508/k8vsvzpf.png

The RND command exist for the Family Basic v3.0
Family Basic v3.0 Reference (PDF)
https://www.sendspace.com/file/kuoud6

Example:

Quote:
10 REM * RND *
20 PLAY "C3D3E3C3"
30 A$="CDEFGABR"
40 N=RND (8)
50 B$=MID$ (A$,N+1,1)
60 PRINT B$;
70 PLAY B$
80 GOTO 40