Rockbox is run from the hard drive or flash memory after being started with a custom boot loader, so to upgrade Rockbox, users need only copy the files onto the player's drive and restart the device.Reflashing is only needed when changing the boot loader, and on some platforms is not needed at all.
Rockbox can be permanently flashed into flash memory on the Archos devices, making it a firmware replacement.
The first of these ports, beginning in late 2004, was for the Cold Fire-powered devices manufactured by iriver, focusing on the H1xx series of hard drive players (H110/H120/H140).
Rockbox runs on a wide variety of devices with very different hardware abilities: from early Archos players with 1-bit character cell-based displays, to modern players with high resolution color displays, digital optical audio hardware and advanced recording abilities.
The Rockbox project began in late 2001 and was first implemented on the early Archos series of hard-disk based MP3 players/recorders (including the flash-only model Ondio), because of owner frustration with severe limitations in the manufacturer-supplied user interface and device operations.
These devices have relatively weak main central processing units (CPU), and instead offload music playback to dedicated hardware MP3 decoding chips (MAS).
Rockbox was unable to significantly alter playback abilities.