Additional Information for some old computer OS:

 
C64/C128: The SuperCPU is a accelerator for the C64 and C128 wich is using the 65C816 16/8 bit processor. The expansion is fully compatible to the C64 or 128 but it boosts it up to 20 MHz, this is 2000% of the original speed. It supports up to 16 MB RAM. A special
C128 version is available. Other accelerator cards wre the TurboProcess (4 MHz) and the Flash 8 (8 MHz, up to 1 MB RAM) by the german maufacturer Rossmöller. Both used the Turboprocess OS, for the
Flash8 a fixed JiffyDOS (below) was available. The Flash8 also supported GEOS.
 
C64/C128 floppy drives: The reason that they are full computers with CPU, RAM and OS was that an computer like the PET or the VIC-20 with 5KB RAM and 1.2 MHz couldn't handle the disk controller functions by software due to lack of memory and speed. So the floppy do this itself and the data exchange is made by a simple serial bus (up to 21 devices are daisy-chained with an unit number, there's support for floppies, printers, harddrives and more - it's like Firewire). It is possible to reprogram the floppy for special purposes, even a use as a co-processor was possible! The most common DOS versions: 2.6 (1540/1541/1551), 3.0/3.1 (1570/1571), 4.0 (8xxx series, Business models), 10.0 (1581) JiffyDOS from CMD is a OS bundle for main computer and floppy drive which replaces the original ROMs. It has an optimized user interface (DOS 5.1) and brings a dramatically disk access speed increase (standard DOS 1541: loading 50K 1,2 minutes - JiffyDOS needs 12 secs for this). There are more different DOS versions for the Commodore floppies like Dolphin DOS or Speeddos which even support parallel data access (normal DOS uses serial access) with hardware modofications. Because the differences and purposes are so different it's a question if the Commodore floppies could be treated as an OS. 
The different MS-DOS versions aren't varying very much, later was added harddrive support and so on, but this wasn't very dramatic.
 
Amiga Platforms: The standard Amigas are using the 68k series (68000-68060), but there are hybrid cards from the german developer
Phase5 which combine an 68040/68060 cpu with an PowerPC 603e
(BlizzardPPC) or 604e (CyberstormPPC) up to 240 MHz. These cards are unique 'cause the CPU structures are different, the 68k cpu is CISC, PowerPC is RISC. The CPUs could be run and programmed fully independendly, but they accessed the sam memory, OS and I/O. Later there were Amiga Clones like the Draco (by Macromedia, a Video cutting system with a licensed AmigaOS) and the PowerPC-based clones like the Genesis or the Amiga One which support up to G4. Normal OS's for these systems are MorphOS and now AmigaOS 4.0.
 
 

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