TeraScale is the codename for a family of graphics processing unit microarchitectures developed by ATI Technologies/AMD and their second microarchitecture implementing the unified shader model following Xenos. TeraScale replaced the old fixed-pipeline microarchitectures and competed directly with Nvidia's first unified shader microarchitecture named Tesla. TeraScale is a VLIW SIMD architecture, while Tesla is a RISC SIMD architecture, similar to TeraScale's successor Graphics Core Next.TeraScale implements HyperZ.