Rio hasn’t published any detailed specs for the Karma beyond the usual product-sheet stuff, so I’ve gathered what backend information I could find about its inner workings. A big thanks to Dave Marsh and everyone over at Riovolution for digging this stuff up.
The CPU is from a company called PortalPlayer. It’s a neat jack-of-all trades chip specifically designed for portable media devices, series PP5002. It’s got two 90Mhz ARM7 RISC processors running symmetrically in 32-bit. One controls the decoding and signal output, while the other handles the interface (buttons, LCD) and hard-drive. It also provides the UltraDMA66 bus and ethernet/USB functions.
The actual buffer memory is only 16MB. It’s been stated that most of that is taken up by fonts and firmware, so the Karma must be making good use of the Hitachi’s APM capabilities to buffer so well and still preserve battery life.
The onboard OS is ECOS, which is a *nix-ish (POSIX-compliant) system for embedded devices. Continued...