The board is connected to J10, pad 15 (leads to R94 and R95, which i then lost under the sound chip), 13 (leads to C55), and 11/10 (which i believe is ground).

Yes, it's a video card, the 4 VRAMs are HM53461ZP-10 with 24 pins. Each has 64k words, each word is 4 bit. So i have 256k 4bit words or 128kByte for all four VRAMs.

Asuming portrait display resolution (640x870), i have 556800 pixels. Then it's not enough space for greyscales in the VRAM, so each pixel is either on or off.