Korg 01/W family DRAM. There are 5 units of these chip in these synthesizers. Early units used M5M4464AL-12, later units used MB81464-10
Used in: Ensoniq ESQ-1, SQ80
My solution is a module that directly replaces the SAD4096
used in DOD 680, MXR M-166, M-205 Stereo Chorus, M-206, Omni, also in Pinball machines Bally Centaur and Centaur II.
Typical symptoms of a malfunction of this chip are:-Half keyboard not working (one chip damaged)-The whole keyboard not working (two chips damaged)-One or several keys not working.
Korg Mono/Poly, Polysix, PPG Wave 2.2/2.3, Kawai/Teisco SX-210, SX-240, K3 and K3m, E-MU SP-12, Drumulator
This chip was initially created by SSM (Solid State Micro Technology for Music) but later in 1988, they sold the rights to PMI (Precision Monolithics, Inc). PMI also sold the rights in 1991 to Analog Devices. Analog Devices does not produce it anymore but you will find them with those different brands and they all are the same product.