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SymbOS operating system on C128??
Dear Bil, dear all, here's the thing: There is a stunning operating system called "SymbOS" on Z80 machines. Have a look at www.symbos.de! It is absolutely amazing and boasts a fully blown multitasking kernal and GUI on a stock Z80 computer (like an Amstrad CPC or any MSX system). Well, the C128 has a Z80! Therefore, it *should* be possible to port SymbOS to the C128. Why? Just because! Wouldn't it be great to have a modern operating system running on "both worlds"? I am in touch with the developer of SymbOS, Jörn Mika, and he already looked into what would have to be done. The main problem from his point of view is the completely different way of using bank switching on the systems. The Z80 systems like the above mentioned can show an arbitrary 16 K block at a chosen address. This simplifies memory management a lot (although SymbOS still needs and has a proper address relocation routine so tasks can be executed at any address). The C128 on the contrary just overlays the banks, with bank 0 optionally shining through at the two common areas. This seems to be the main problem which would require a lot of changes in the SymbOS kernal. Everything else (like using the VDC as graphics chips or the 1571 drive as disk drive) should be no problem according to Joern. On the other Z80 systems, SymbOS of course also supports additional hardware like up to 1 MByte of RAM, IDE hard drives etc. Now, who would be willing and capable of helping SymbOS rise on the Commodore 128, our favorite computer? Merry christmas everyone! Christian www.amiga600.de www.retropulsiv.de
That is pretty awesome, looks
That is pretty awesome, looks quite advanced too for the time when it was designed. Is this just a conceptual project or is this likely to happen? I would love to have options other than GEOS on my 128 :)
Re: SymbOS operating system on C128??

I've sent the link of this discussion thread to the programming types at


Merry Christmas,
Robert Bernardo
Fresno Commodore User Group

I've also had "some" :)
I've also had "some" :) conversation (btw, in real life too, once) with Prodatron (Jörn Mika) since eg I helped him to port SymbOS to the Enterprise-128 (a quite interesting Z80 based computer). Though I always treated myself as more a 65xx/Commodore guy than Z80 based stuffs, Commodore 128 is still a white spot for me. For example I couldn't managed to find an easy to understand description on certain C128 related topics, ie the MMU (how it exactly works, relation with Z80, etc), the Z80 itself (how it works exactly, on what effective clock, is there really "fast" mode for Z80 in C128 - since I've read the initial problems led to have much slower effective clock in the C128 as the usual native Z80 configs with ~4MHz, thus C128 was a "poor" CP/M computer being "too slow" because of that issue), and the VDC itself. Documentation what I could found are all seem to be quite missleading or hard-to-understand for me, but of course, it can be me who is the problem :)
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