The 'f' directory contains the RISC OS screen and sprite device drivers
and other RISC OS Fortran code for PGPlot.
You can add other drivers by modifying the subroutine GREXEC and
downloading them from the PGPlot website (below); E.g. I find
the postscript driver useful for conversion to pdf with Ghostscript.
(The RISC OS driver is also there but is probably out of date).

The application '!PGPlot' contains two files of data: grfont (definitions of
the Hershey fonts) and rgbtxt (colour definitions) needed by PGPlot.
The !Run sets up global variables which you may wish to change.

You will need to make a PGPlot library from the Fortran of PGPlot
(or ask for a copy from Fortran Friends) which you should load first
in !FDE, followed by:
Utilities
Graphics &
SpriteOp
   in any order.


The Fortran PGPlot graphics subroutine library is copyright CalTech
but may be obtained from their web site:

http://www.astro.caltech.edu/~tjp/pgplot/

where you can also find lots of documentation and helpful examples.