We have already stepped through many of the technical details of Llano in our coverage of the mobile platform, but we’ll touch on some of the high level details again here.
Llano APU Die Map
Llano, in its current form, consists of four AMD “Stars” class CPU cores fused with a “Redwood” class, Radeon HD 6000-series GPU core, with up to 400 stream processors. Although based on similar CPU cores, the L3 cache used on current Phenom II processors has been eliminated, but the L2 cache per core has been increased from 512K to 1MB. Llano-based APUs are manufactured using Global Foundries’ 32nm HKMG process and consist of roughly 1 Billion transistors. In addition to the CPU and GPU cores, a northbridge and dual-channel DDR3 memory controller reside on-die, along with AMD’s UVD video engine, 24 lanes of PCI Express Gen 2 connectivity, and various digital display interfaces.
Llano's "Sumo" Integrated APU
As we’ve mentioned, the graphics core used in Llano is derived from existing DirectX 11-class Radeon GPUs, so the above block diagram should look familiar to regular HotHardware readers. In the A8-3850 APU we’ll be looking at today, 400 shader or Radeon cores are present. They’re arranged in five SIMDs, with texture units and L1 caches attached. Other A-Series APUs will be offered with 320 Radeon cores as well, which means one of the integrated GPU’s SIMDs will be disabled. The command processor, graphics engine, and dispatch processor, as well as the UVD 3 video engine and display controller configurations found in discrete Radeon GPUs are all present here. In fact, the GPU core in Llano (which itself if codenamed “Sumo”) is very similar to the “Redwood” GPU at the heart of the Radeon HD 5670. The GPU is linked to the APU's northbridge and ultimately the CPU cores through the Radeon Memory Bus and a new Fusion Compute Link, but AMD is keeping details of said link quiet for now.
To connect Llano to the rest of a system AMD is also readying a couple of new desktop chipsets, the A75 and the A55. The combination of a Llano APU with A-Series chipset-based motherboard is what AMD is calling the “Lynx” platform.
AMD A75 Chipset Diagram
We’ve got a block diagram of the A75 chipset for you here, but the A55 is very similar. The A75 offers six SATA 6GB/s ports, with RAID 0,1,10 support and FIS based switching, HD Audio, 4x1 PCI Express Gen 2 lanes, 4 USB 3.0 ports, 10 USB 2.0 ports, and 2 USB 1.1 ports. In addition there are SD and IR controllers present, PCI support (for up to three slots), and mSATA support. The A55 is similar except that its SATA ports are of the 3GB/s variety and it doesn’t offer FIS based switching or native USB 3.0 support, so 14 of its ports are USB 2.0. The chipset connects to the APU using AMD’s Unified Media Interface (UMI), which offers 2GB/s of bandwidth.