Core module

The use I am familiar with is that the core module is the microprocessor instruction execution engine, containing ALU and memory. It might contain traditional on-board I/O, but not extended I/O capability. One way to get extended capability is to plop down a processor core module without significant modifications, then place additional I/O, memory, etc, around it.

This often leads to the trickiness of using, say, 8051 "external memory" that is actually on chip. In that case the memory uses the addressing mode that was originally used with physically separate memory. The documentation can get confusing if you aren't aware of the layering.

A core module saves time for the microcontroller designer, since he can slap down a proven core design, rather than start from scratch. It can save the user time because of familiarity with the core architecture and maybe allow use of existing non-portable code with minimal changes.

If what you're saying is about core modules for CPLD/FPGA then it is a design (VHDL/Verilog ect.) like: PCI Core (PCI Interface Module)

- used to allow interfacing of your custom card to PCI PCI Express Module MicroBlaze... etc.

So instead of creating these modules you will just snap it with your current design. Saves a lot of time developing and debugging.

For more info: try MegaCore (ALTERA) of LogiCore (XILINX)