We have been talking a lot about AMD’s upcoming Zen CPU core micro-architecture. We know that AMD is working on a 16-core APU and a 32-core Opteron processor using this architecture. This new core design will be a departure from its Bulldozer multicore module design and will be a monolithic core design. Zen will be much like “Stars”, which was the core design that AMD used in its Phenom series, except Zen will have a lot more horsepower!
Zen will feature monolithic fetch and decode units. Compared to Bulldozer where two cores inside a module featured dedicated decode and integer units with shared floating-point units. So on Zen you have a monolithic decode unit, and single integer and floating points. The integer unit has six pipelines, compared to the four per core on Bulldozer. The floating point unit has two large 256-bit FMAC (fused-multiply accumulate) units, compared to the two 128-bit ones on Bulldozer. The core of Zen has a dedicated 512 KB L2 cache, this is much smaller than the 2 MB per core on Bulldozer, but the Zen core is able to push things through fast enough where it does not need a large cache buffer. In a multi-core Zen chip the cores will converge at a large last-level cache that will route the data between them to the processors uncore, which will feature a DDR4 IMC and a PCI-Express 3.0 root complex.