In 1987 I worked for a contracting company which provided system software support for a Honeywell 6680 mainframe which happened to have a C compiler.  I assume this compiler was based on the one mentioned in the paper.  I recall it being difficult to port C source to the mainframe due to its inability to address anything smaller than a 36 bit word.  I did manage to port a program in my spare time which generated images from the Mandelbrot set on the IBM PC.  What took 10+ hours to generate on a fast PC of the time took a mere 3 minutes on the mainframe.