中文 English

Author's Latest Posts


The Road To Domain-Specific Accelerators


For about fifty years, IC designers have been relying on different types of semiconductor scaling to achieve gains in performance. Best known is Moore’s Law, which predicted that the number of transistors in a given silicon area and clock frequency would double every two years. This was combined with Dennard scaling, which predicted that with silicon geometries and supply voltages shrinki... » read more

What Is An ASIP?


ASIP stands for “application-specific instruction-set processor” and simply means a processor which has been designed to be optimal for a particular application or domain. General-purpose versus application- or domain-specific processors Most processor cores to date have been general-purpose, which means that they have been designed to handle a wide range of applications with good average... » read more

What Does RISC-V Stand For?


RISC-V (pronounced “risk-five”) stands for ‘reduced instruction set computer (RISC) five’. The number five refers to the number of generations of RISC architecture that were developed at the University of California, Berkeley since 1981. The RISC concept (like the parallel MIPS development in Stanford University) was motivated by the fact that most processor instructions were not... » read more

Customizing An Existing RISC-V Processor


In a previous post, we considered how you could create an optimized ISA for a domain-specific processor core by profiling software and experimenting with adding/removing instructions. Using the open RISC-V ISA can be a great starting point for a processor that combines application-specific capabilities and access to portable software. The old-fashioned way to modify the instruction set wo... » read more

ISA Ownership Matters: A Tale of Three ISAs


An instruction set architecture (ISA) is crucial to the development of processors and their software ecosystems. In the last half century, the majority of ISAs have been owned by single companies, whether product companies for their own chips/systems or processor IP companies who licensed their processors to chip developers. Does ISA ownership matter? Let’s consider three proprietary ISAs a... » read more

Open Source Vs. Commercial RISC-V Licensing Models


Everybody is familiar with commercial licensing from traditional processor IP vendors such as Arm, Cadence, and Synopsys. But in discussing the RISC-V Open Instruction Set Architecture (ISA), there is widespread confusion of terminology with RISC-V often being described as “open source.” Some have even accused vendors of commercial RISC-V IP such as Codasip or Andes as not being in the spir... » read more

Impact Of Instruction Memory On Processor PPA


The area of any part of a design contributes both to the silicon cost and to the power consumption. A simplistic following of the “A” in a processor IP vendor’s PPA numbers can be misleading. A processor is never in isolation but is part of a subsystem additionally including instruction memory, data memory, and peripherals. In most cases, instruction memory will be dominant and the proc... » read more

Embedded Processor Requirements And OS Choice


For each embedded product, software developers need to consider whether they need an operating system; and if so, what type of an OS. Operating systems vary considerably, from real-time operating systems with a very small memory footprint to general-purpose OSes such as Linux with a rich set of features. Choosing a proper type of operating system for your product – and consequently w... » read more

Defining Processor Core Complexity


The more complex a processor core, the larger the area and power consumption. But increasing complexity is not a single dimension, as processors can be more complex in different ways. In selecting a processor IP core, it is important to choose the right sort of complexity for your project. Some ways of thinking about complexity include: Word length Execution units Privilege/prot... » read more

Understanding The Performance Of Processor IP Cores


Looking at any processor IP, you will find that their vendors emphasize PPA (performance, power & area) numbers. In theory, they should provide a level playing field for comparing different processor IP cores, but in reality, the situation is more complex. Let us consider performance. The first thing to think about is what aspect of performance you care about. Do you care more about the ... » read more

← Older posts