GUI64 – GUI for the Commodore 64 running on top of the built-in ROM

Grimeton

One word: GEOS

ButlerianJihad

Limitations: GUI64 does not use the VIC-II’s bitmap graphics mode, but operates in text mode. GUI64 is therefore character set–based... Strictly speaking, GUI64 should therefore be considered not a GUI, but a TUI (Text User Interface). Currently, there are no applications for GUI64. So, it is a file manager, inferior to an orthodox file manager. It supports the mouse, and it can launch BASIC. If you like your KERNAL ROM, you can keep your KERNAL ROM. I never ran GEOS. I saw it advertised, and it seemed fascinating, but perhaps "too early". I had become fluent in BASIC and proficient at the command line. I could decipher the DOS commands and device IDs. For me, time spent on the Commodore 64 was programming, or in a game or application, rather than pushing files/objects around on the desktop.

snvzz

Too bad it's not open source. ("NC" creative commons)