lol, I'm also or was at one time factory Apple trained. Spent three weeks in Apple school on software. IBM had won a national service account and we had one local unit of Apple stuff. I never turned down any school and was the only Apple trained service person in our area, The real funny thing about it is I went and met the local Apple customer who previously did all their own service and software and continued to keep doing it. Never had one service call on any of their products or software. Apples training was pretty much only to learn how to make a dos diskette to get online to get a new software load for what ever you were working on. Never took one service call yet factory trained. Nortel was another company who I trained on, got a free cell phone for years from and never had to take a service call at a Nortel location. Used the training on other Nortel network customers of ours but never a real Nortel service call. You mentioned DOS. My initial A+ testing required by many customers was mainly on DOS which was then current. ...
DOS, OS/2, Linux(and most all it's variations), Unix, AIX, Nortel, Bell, Cisco, Netapp, HP, Dell, Motorola, Compaq, Colbol, Fortran, Unisis, Reuters, Novell and on and on all at one time factory trained.