In systems with AMD processors, what allows communication between processors and the I/O
subsystem?

A.
Northbridge

B.
Southbridge

C.
HyperTransport link

D.
APIC

E.
QuickPath Interconnect

Explanation:
Industry Standard Architecture – Student Guide 1 – Page 37
AMD processors are able to communicate with each other through HyperTransport point-to-point
links. This enables one processor to access the memory connected to another processor. Inside
the processor, a crossbar switch connects the processor, memory controller, and HyperTransport
links.
AMD processors also use HyperTransport links to connect to the I/O subsystem.
The links on particular processors are connected to I/O tunnels that support the I/O devices.
All other processors can communicate with the I/O system through the HyperTransport links.
Legacy devices are also connected to one of the I/O tunnels.