PLC wannabe
Member
OP
Again, I'm just guessing but maybe the .prg file contains the info for the ladder instead of the .lad file required by the software version 6.25 that I am familiar with. Some of my old software for another type plc used a .prg file name. It might be just a very early version of the Icom software that was used. Look around where you found the old floppy that had the files you posted to see if you can find any software by Icom. Maybe even an old computer or boat anchor sized terminal.
EDIT:
Yippee! I found a way to import the files into version 6.25. I see them as a ladder diagram with each instruction labeled. Now to just get a printout.
You see a ladder from my files???!!!