Going down further in the hierarchy, the Grand Central chip is a sort of I/O bus for miscellaneous logic board devices. Both the ANS and the PM9500 use the CURIO chip (AM79C950, custom part from AMD) to support serial ports, a slow (5 Mbit/s, 53C94/96 based) SCSI bus and 10Mbit/s ethernet. The SWIM floppy controller is also common to both machines and connected through the Grand Central chip. The ANS lacks the MESH SCSI chip (53CF94/6 derived Apple SCSI chip) which is present on the PM9600 and supports the internal Fast SCSI bus.