Format of S3 memory-mapped subsystem registers

Offset  Size    Description     (Table M102)
8504h  DWORD subsystem Control/Status Register (see PORT 42E8h)
8508h  DWORD ???
850Ch  DWORD advanced function control (see PORT 4AE8h)

See Also: #M095,#M100,#M103
--------V-MA0008580--------------------------
MEM A000h:8580h - S3 - MEMORY-MAPPED DMA REGISTERS
Size:  32 BYTEs

Note:  the S3 graphics processor registers can be mapped at either
     linear 000A0000h or at offset 16M from the start of the linear
     frame buffer