I am wondering

Uhmmmmmmmmm, lets see Windows 95, 98, 2000, NT, XP, and Vista.

But now I am back with XP Pro

Try going back to assembler and working forward from there!

Mac OS Classic m68k and PPC, Mac OS X PPC (didn't like it much), GNU/Linux PPC and i386, Haiku, Syllable (Atheos), ReactOS, OpenSolaris i386.

Oh... and Windows.

Let's see...

I started out on an old O/S used by Sperry Univac called "Exec 8" back in the 1960s. This was in high school.

In work, the first I used was an O/S called MCP (for "Master Control Program") that ran an already long obsolete Burroughs B-5000 that they were using for accounting at the U.S. Department of Justice. Then I set off on smaller, more decentralized computing, writing primitive routines under an O/S with a name I don't remember that powered Raytheon's early "Lexitron" word processing devices. Then these were replaced with slicker new OA machines from NBI running a VERY proprietary O/S called NBI/OS.

(Unknown to everyone, even those working at NBI at the time, was that NBI stood not for "Nothing Better Invented" or "Not By IBM" as they'd tell you, but for "Necton Bilunium Incorporated," a name I personally thought was very cool sounding.)

I then used a strange O/S called "MARU" that ran on a bank of HP mainframes that had been optimized for interpreting EKG's.

I then used an O/S called "PrimOS" that had some interesting quirks, like its greeting on bootup "Yo Adrian."

Then I became familiar with DOS, and the first machine I owned myself was a $3,000 PC-compatible that was the bee's knees at the time, with 640K of RAM, TWO floppy drives and an AMBER monochrome monitor! It was really the cat's pajamas, the latest and greatest! A year after I got it I added a 20MB hard drive and I thought I was set for life!

Then I really got into it in what we called a "heterogenous environment" with a wide range of different computers including DEC VAXes running VMS, IBM AS/400s running MVS, and a WIDE range of Unix boxes running (Sun) SunOS and Solaris, (HP) HP/UX, SGIs running Irix, Apollos running Domain, some desktops and minis running open source Unix like vanilla BSD and Linux, and my favorites, IBM RS-6000s running AIX. Those IBMs had the best bang for the buck, and enjoyed BY FAR the best product support from the vendor.

And, of course, I've used every form of Microsoft's Windows from the very strange and crude 1.0 through Vista. I'll tell you, I REALLY like Vista!

One thing I HAVEN'T used beyond occasionally trying to troubleshoot some data communications problems on them is anything that runs on a Mac. I really wish that Apple would focus on their IPods and IPhones, because, unlike personal computer communications and data handling, they're good at that.

Debian, BSD, Windows NT, Windows FAT, and DOS.

Microsoft oses since MsDos 1.1 to Windows XP.

Concurrent CPM first version i don't remember what number that version was.

Red Hat Linux 5.1, Suse mmm, don't remember version number, Debian 2.4 to 2.6 kernels.

Not to many but enough.

Lets start with the mainframe: VM, CMS, CICS, VSE, MVS, DOS, OS/360, OS/390

Digital Equipment: PDP-8, DOS-11, RSX-11, IAS, RT-11, RSTS/E, VME, VMS

Mid-range: Unix, Xenix, AIX, CTOS, Multics, TOS, RDOS, Pilot, QDOS, SunOS, SCO, Solaris, SYSTEM 32, System 36, DG/UX, VOS

PC: PCDOS, MSDOS, CPM, MPM, COCO, TRSDOS, DosPlus, LDos, NEWDos, VTOS, AppleDOS, Commodore64, Timex ZX81, BEOS, GEM, GEOS, DRDos, NETWARE, AmigaOS, AtariTOS, Mac Classic, Mac OS, OS/2, QNX, Linux, Windows 95/98/me, Windows NT/2000/XP/2003/Vista, eCommstation, FreeDOS, ReactOS

I think that covers most of them.

randy