(Authored by Micheal Naquaada; Posted by s-person)

A friend mailed me the link to the Javvin OS map(http://www.javvin.com/computer-operating-systems-os-map.html). I'm working with computers for over 20 years, starting with the Commodore VC-20. I had the most common systems, but know a lot of OS's which aren't known so well. I have made a list with a little description.  

8-bit:
 
- GEOS 64
- GEOS 128 (support for more memory and 80-column display)
- Apple ][ GEOS
- plus/4 GEOS (illegal crack)
- Wheels (special GEOS-based OS for C64/128, supports 'The Wave', an 80-column web browser with graphics if you're using a SuperCPU*)
- GEOS MegaPatch 3 (another GEOS enhancement)
- Contiki (multi-platform, supports Internet connection)
- Wings (for C64 + SuperCPU, Realtime multitasking OS with internet connection, based on the JOS kernel)
- JOS (C64, Unix/Linux based OS)
- SymbOS (Schneider CPC series)
- CAOS (Schneider CPC)
- CAOS 4.2 (KC/85 from the former GDR)
- CP/M 3.0 for C128
- MSX Computer Series, Similar to MS-DOS?
- All Commodore floppy drives had an own operating system 'cause they are complete computers with own RAM, CPU and I/O.*
 
16/32 bit:
 
- AmigaDOS (text-based OS of the Amiga)
- AMIX (AMiga unIX, A real UNIX System V Version 4 which was for use only on the Amiga 2500UX/ 3000UX platform, 68020/030 and SCSI required)
- AmigaOS 3.5 / 3.9 (AmigaOS enhancement by Haage & Partner, Germany)
- AmigaOS 4.0 (Amiga PowerPC platform, by Hyperion)
- AmigaOS XL (Native AmigaOS (without custom chips) running on PC platforms using QNX RTOS microkernel)
- QNX RTOS (microkernel OS, first versions included OS, TCP/IP, browser and more on a single 1,44MB disk)
- p.OS (Portable OS, amiga-based, should be portable)
- MorphOS (for Amiga-Clones and PowerPC-based Amigas*)
- Linux versions for Amiga, 680x0 series and PowerPC series are available
- GeoWorks Ensemble/ NewDeal Office (alternative graphical OS for MS- DOS platforms)
- Lisa OS (predessor from MacOS)
- TownsOS (Fujitsu FM-Towns OS, only available in Japan)
- MS-DOS compatible text-based OS's like PC-DOS or DR-DOS?
 
How about the Operating systems in old computers with BASIC interpreters at start, they are also a kind of operating system. If you compare the Sinclair ZX81/Spectrum BASIC interpreter with the ones made by Commodore (which is Microsoft BASIC) yo'll see that it they are way different.
 
I know about 20-30 operating systems and have used the most of them (for a shorter or longer time), and my personal favourite is MacOS X cause its perfect. The second is GEOS C64/128 because it's excellent programmed. It's an OS like the 16-bit Mac Classic in 23 KB size. The
C64 has only 64KB RAM, and there go 16KB for Video RAM, some more RAM for other things so you have about 10KB free for programs. The DTP program GeoPublish has a file size of 99KB - it's working on because a new file format which supports file sizes up to 4MB. At these times on a disk fit 165K, so this was enourmous. GEOS supports WYSIWYG display, RAM expansions, accelerator cards, harddrives, cd-roms, even Laser printers are supported. And this on a computer with 0.9 MHz!

Greetings, Michael.