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The Versal ACAP is Xilinx's latest FPGA product and is the successor to the Zynq UltraScale+. It combines an FPGA, real-time processor (2x ARM Cortex-R5F), application processor (2x ARM Cortex-A72), and an AI engine into one chip. A Network-on-Chip (NoC) connects all of these components.
The main upgrades from the UltraScale+ to the Versal are the NoC interconnect and the AI engine. We'll soon publish a more in-depth article about the Versal AI engine. In short, it's an interconnected collection of small processor cores which excel at AI/ML and DSP tasks. Each AI core is a mini-processor that can execute scalar instructions and parallel vector (VLIW SIMD) instructions - so the AI engine is much more flexible than a GPU. Xilinx makes two versions of the AI engine array, one suited for DSP tasks and one suited for ML inference tasks. Xilinx refers to the DSP-focused version as the AI Engine (AIE) and the ML-focused version as the AIE-ML.
Additionally, the PL (programmable logic), aka FPGA on the Versal ACAPs contains dedicated DSP engines. These are separate from the AI engines (even the DSP-focused AI engines). The amount of DSP engines on a chip depends on the size of that chip's FPGA - Versal models with larger FPGAs have more DSP engines.
Xilinx also has some new names for the chip components:
- The ARM cores are the "Scalar Engines" (previously called APU on UltraScale+)
- The FPGA is called the "Adaptive Engine"
- The AI cores and DSP engines are collectively referred to as the "Intelligent Engines"
The Versal lineup is divided into five product series.
Every Versal, regardless of its series, has a NoC and has the same Scalar Engine (2x R5F + 2x A72). And every Versal has DSP engines in the PL.
- The AI Edge (VE) series is the smallest version of Versal - the FPGAs on these range from 20k to 500k LUTS. The size of the AI engine ranges from 8 to 300 cores. Most AI Edge products have an ML-focused AI engine, but one AI Edge chip is available with 300 DSP-focused AI cores.
- The AI Core (VC) is larger, with the FPGA ranging from 250k to 900k LUTs. Most AI Core products have a 130-400 core DSP-optimized AI engine, but some AI Core chips are also available with the ML-optimized AI engine (up to 300 cores).
Xilinx also makes a military and space-grade Versal. The Versal XQR is a radiation-hardened version of the AI Core VC1902 chip, with 900k LUTs and 400 DSP-focused AI cores. See XMP490 for details.
All AI Edge and AI Core series Versal ACAPs have an AI engine. The remaining three series mostly do not have an AI engine - they only have the ARM cores and FPGA, much like an UltraScale+.
- Versal Prime (VM) ACAPs are small-midsize chips without an AI engine. The FPGAs range from 150k to 1 million LUTs.
- The Versal Premium (VP) series has large FPGAs, from 380k to 3.3 million LUTs. Most Versal Prime chips do not have AI engines, but two chips are available with 470 DSP-focused AI engines.
- The Versal HBM (VH) series do not have AI engines but are equipped with up to 32 GB of on-chip HBM.
For more information, refer to DS950: Versal Architecture and Product Data Sheet: Overview.