 The main CPU of the Sega CD is a <unk> 16 @-@ bit Motorola 68000 processor , which runs 5 MHz faster than the Genesis processor . It contains 1 Mbit of boot ROM , allocated for the CD game BIOS , CD player software , and compatibility with CD + G discs . 6 Mbit of RAM are allocated to data for programs , pictures , and sounds ; 512 Kbit to PCM waveform memory ; 128 Kbit to CD @-@ ROM data cache memory ; and an additional 64 Kbit are allocated as backup memory . Additional backup memory in the form of a 1 Mbit Backup RAM Cartridge was also available as a separate purchase , released near the end of the system 's life . Audio is able to be supplied through the Ricoh <unk> , and two RCA pin jacks allow the Sega CD to output stereophonic sound separate from the Genesis . Combining stereo sound from a Genesis to either version of the Sega CD requires a cable between the Genesis 's headphone jack and an input jack on the back of the CD unit . This is not required for the second model of the Genesis . 
