Editing Commodore 64 (section)

=== Alternative operating systems ===
Many third-party operating systems have been developed for the C64. As well as the original [[GEOS (8-bit operating system)|GEOS]], two third-party GEOS-compatible systems have been written: Wheels and GEOS megapatch. Both of these require hardware upgrades to the original C64. Several other operating systems are or have been available, including WiNGS OS, the Unix-like LUnix, operated from a command-line, and the embedded systems OS [[Contiki]], with full GUI.  Other less well-known OSes include ACE, Asterix, DOS/65, and [[GeckOS]]. C64 OS is commercially available today and under active development. It features a full GUI in character mode, and many other modern features. A version of [[CP/M]] was released, but this requires the addition of an external [[Zilog Z80|Z80]] processor to the expansion bus. Furthermore, the Z80 processor is underclocked to be compatible with the C64's memory bus, so performance is poor compared to other CP/M implementations. C64 CP/M and C128 CP/M both suffer a lack of software; although most commercial CP/M software can run on these systems, software media is incompatible between platforms. The low usage of CP/M on Commodores means that software houses saw no need to invest in mastering versions for the Commodore disk format. The C64 CP/M cartridge is also not compatible with anything except the early 326298 motherboards.{{citation needed|date=April 2018}}