1 2The SGI Visual Workstations (models 320 and 540) are based around 3the Cobalt, Lithium, and Arsenic ASICs. The Cobalt ASIC is the 4main system ASIC which interfaces the 1-4 IA32 cpus, the memory 5system, and the I/O system in the Lithium ASIC. The Cobalt ASIC 6also contains the 3D gfx rendering engine which renders to main 7system memory -- part of which is used as the frame buffer which 8is DMA'ed to a video connector using the Arsenic ASIC. A PIIX4 9chip and NS87307 are used to provide legacy device support (IDE, 10serial, floppy, and parallel). 11 12The Visual Workstation chipset largely conforms to the PC architecture 13with some notable exceptions such as interrupt handling. 14