What is meant by a soft core processor?

A soft core processor refers to a microprocessor core that can be wholly implemented using logic synthesis. It can be implemented via FPGA (Field-Programmable Gate Array) or using ASIC (Application-Specific Integrated Circuit) design flow. It is called "soft" because it is implemented in software (such as VHDL or Verilog) that describes hardware, which can be easily altered, as opposed to "hard" processors, which are physical devices.

Here are the steps to understand it:

1. Understand the term "core": In computing, the core is the part of a processor that receives instructions and performs calculations, or actions, based on those instructions. A set of instructions can be in simple form such as "add two numbers" or complex ones like "draw a 3D image".

2. Understand "soft core": A soft core is a description of the hardware in a high-level language like VHDL or Verilog, which can be synthesized or compiled into the configuration of an FPGA or the layout of an ASIC.

3. Understand the difference between soft and hard cores: The difference between a soft core and a hard core (like those in your Intel or AMD processor) is that the hard core is a physical piece of silicon while the soft core is a description of how a piece of silicon can work if it is designed that way.

4. Understand the application: Soft cores are used when you need a processor that is tailored to a specific application. The advantage is that you can make a processor that does exactly what you want, no more, no less. This can result in significant cost, power, and performance benefits.