I've Xeroxed the two sections from the HP150 Programmer's Reference
Manual that deal with Touchscreen escape sequences and mailed them
off to Gary Biggs.  A  looooonnngg  time ago I wrote some C programs
on the 150 to draw boxes and create touch areas, and respond to
someone touching the screen, but I don't remember much about it.

C compilers written for IBM PC's worked just fine on the HP150,
once I figured out how to transfer them from the IBM PC using a
combination of Kermit and Xmodem, or something like that.
That was before the newer HP150's had the capability of reading
IBM-formatted floppy discs.

Cecile Chi