I've been wrestling with my PC for the past few weeks, but it is finally stable enough that I have had time to post the Processor Technology PTDOS 1.5 User's guide on my web site. PTDOS was contemporaneous with CP/M, but it was a lot more sophisticated in some ways. But don't believe me, just read it for yourself. http://www.thebattles.net/sol20/soldocu.html (the PTDOS manual is near the end, broken up into the core OS chapters in one PDF, and another PDF containing a chapter for each of the various bundled applications).