The last story was about PF.EXE, a file-processing utility I wrote for my own uses way back when. That one was a combination of C code and 8086 assembler, written for MS-DOS (worked fine in Windows), that read and wrote disc files. It had a toolkit of things it could do to them, depending on command line switches.
Many years later, using Java, I created more capable versions, the culmination of which was a suite called DataBridge. It turned out to be some of the most valuable work I ever did for The Company.