If you're feeling nostalgic for your long-retired Commodore 64 and you've a spare Raspberry Pi laying around, the Commodore Pi is right up your alley: an emulated Commodore 64 operating system for the small modern computing unit.
The Commodore Pi is presently a work in progress, aiming to bring the classic computer's operating system to the Raspberry Pi. The work is based upon the foundation set by the Comeback64 emulator.
In time, the folks behind it hope to include sprites, joystick support, SID sound, and eventually there could be "additional modern graphics modes" added, as well as changes in its emulation speed.
The project is already under way, as you can see in the video above, and part of the goals include adding access to Ethernet and USB, among others, as well as stereo speakers and support for the SD card. You can grab your own copy from the Commodore Pi website.