I cut my Assembly teeth on S/360. In those days IBM source code was widely available and provided an excellent practice example for learning Assembler and the f

I cut my Assembly teeth on S/360. In those days IBM source code was widely available and provided an excellent practice example for learning Assembler and the finer points of various instructions. We should not forget that macro processing vastly expanded the power of Assembly language. There is an analogy with DCF, Document Composition Language. The first MarkUp Language was GML which was a set of DCF macros. GML evolved into BookMaster which underlayed IBM becoming the world's second most prolific publisher. I wrote XPSProf which was a DCF ML used by Xerox Canada for writing manuals for its IBM compatible software offerings.