PocketDOS/Arm : try the Geos Ensemble (tm) OS
Geos Ensemble is a 16 bits graphical OS which runs on MS-DOS file system. The rights are owned by www.breadbox.com, which site is interesting for the devices which ran Geos code. You can pay a visit safely to their web site, and may download the Ensemble Lite demo version at :
http://www.breadbox.com/downloads.asp?category=Ensemble Lite&maincategory=Ensemble Lite
Place the Geos files with WinImage shareware on a partitionned and formated virtual disk created within PocketDOS, and lauch your Dos environnment from A:>, a booting virtual floppy with FreeDos 7.10
You cant get a FreeDOS booting floppy from Oxford JPC (Java PC) : you just rename the JPCApplication.jar JPCApplication.zip and extract floppy.img with WinZip or Total Commander under Windows XP or Seven.
Check that your Geos.ini configuration file is set with
fs = os2.geo
launch the OS via Ensemble.bat
and enjoy ! The rights for this system make it affordable for Educationnal Institutions who can't pay numerous Windows licenses, and if you like it, you can purchase one or several licenses from Breadbox. Note that Geos can manage touch screen pen based tablets.