NEO-MGA
The NEO-MGA-T is a damn chip nobody knows about, which is found in the CD1 and CD2 versions of the NeoGeo hardware. The CD-Z has a NEO-MGA-T2, probably to handle the faster CD reading speeds and new copy protection system. The front loading NeoGeo CD has a NEO-MGA chip.
It's in charge of the communication with the CD drive, data transfers to the LC89515 host and buffering CDDA data for the BIOSes vu-meters.