This page, still current:
http://pckdos.sourceforge.net/
Contains the source files for pckdos
(Arxip
arxip@users.sourceforge.net
) and also that for J. Wall's pdosbox 2 from which pckdos was derived.
https://sourceforge.net/projects/pckdos/files/pckDos_063/001/pckDos_063.001_Sources.zip/download
https://sourceforge.net/projects/pckdos/files/pckdos-pDosBox/pDosBox_063-b2_Wall/dosbox063R2.0.rar/download
The readme states It's the original Source by Wall.
I think he used that maniach mingw compiler to compile it.
The copyright of the files has been transfered to the DOSBox Team.
And you can use it under GPL v2 license
(just like the original DOSBox files
).
I'm documenting this here as it might be possible to compile for hpc2000 J720 with better screen support.