> I'm sorry, you're mistaken. By 87 DOS was multitasking, doing advanced memory > management etc.
That's not all that correct. The only MS-DOS multitasking most people did in '87 was TSRs, and "advanced memory management", such as it was, was achieved by loading add-ons in CONFIG.SYS (flat-model DOS extenders were still about 3 years away at that point).