The Direct Connect Architecture is the I/O architecture of the Athlon 64 X2, Opteron, and Phenom microprocessors from AMD. It consists of the combination of three elements:
- The microprocessor is directly connected to DRAM memory through an integrated memory controller.
- The microprocessor is directly connected through a natively implemented HyperTransport to a high performance I/O subsystem.
- The microprocessor is optionally directly connected to other CPUs through a proprietary extension running on top of additional natively implemented HyperTransport interfaces allowing support of a cache-coherent Non-Uniform Memory Access (ccNUMA) multi-CPU memory access protocol and symmetric multiprocessing (SMP).