CP/M for the C64
Unlike the C128 the C64 wasn't directly compatible with CP/M operating system but had an add on Cartridge giving the C64 an external Z80 CPU, however this was neither a great commercial success neither really usefull.
To understand why the CP/M cartridge wasn't a great success we have to take a look at the limitations that make it not so usefull.
1st most CP/M system where designed for at least 80 col terminal, the VIC-II is 40 col making most CP/M software looks akward and unusable.
2nd the TPA (Transiant Program Area) was short, only 44K against the 56K of the C128 or the 60K of most other CP/M system this was a downside
3rd the system was designed for 1 drive operation.
if you want to know more about cp/m for the C64 i recomend you to visit this page : http://www.z80.eu/c64.html
Now to make CP/M at least a bit usefull we need 2 things, the 80 col softdriver from the page above mentioned and the basic program to patch it for 2 drives operation.
Note that the 80 col softdriver will not make every cp/m software automaticaly works like intended on the C64 because the C64 isn't standard terminal so it is usefull but limited.
2 drives operation on the other hand we absolutly want that, using cp/m with 1 drive only is total crazyness of disk swaping, since the patch itself is a simple basic program that seems pretty easy enough but...
My First attempt horribly failed lending me on a plain green screen and drive lock at track 3. the disk sources was the first disk from http://www.zimmers.net/anonftp/pub/cbm/demodisks/c64/cpm/index.html
Second attempt with the second disk from zimmers.net failled too this time drive locked at track 2 at the end of the loading indicator.
Third attempt and third disk, worked like a charm. i dunno why the 2 others failed but here it is and for saving you the trouble i uploaded the patched disk on commodoreserver.com you can find it in Public/apps if you want to give it a try.