Initially sold for ¥7,000
The Yamaha RAM4 is a cartridge to be used in compatible Yamaha products that can store three different types of data: Voice & Performance, Fractional Scaling and Micro Tuning. It's the updated design of the RAM1 cartridge previously available for the DX7.
The RAM4 Voice & Performance Memory is equivalent to the DX7II Internal Voice & Performance Memory. The Fractional Scaling Memory holds up to 64 Fractional Scalings, which are tied to the 64 Voices in the DX's Internal Memory. The Micro Tuning Memory holds up to 63 Micro Tunings.
The cartridge can also be used on the TX802, DX11, RX5, RX7, G10C, MSS1 and DMP7. A bigger yet more rare version was also available, called RAM5.