Andy:
I agree that the standard available tools such as Keil will let you compile the code for an embedded core design.

What you usually end up having to roll in your own is some methodology for doing code download, test and debugging. To me writing code is one thing but I rarely approach a development unless there is a GOOD or VERY GOOD download test and debug environment in place.

It is for the above reason that I chose to use Cygnal parts over all others!! The onboard support for the above is AAA+++.

Now I suppose that a Cygnal style JTAG debugging system with hardware breakpoints, watch points, register & memory sniffing, and single step and reset control is available from some where as IP it is yet another piece to buy, design in, and get working.

We cannot also forget the more generic types of chips such as Cygnal and Triscend have on board FLASH and in some cases substantial amounts of RAM. FPGAs with enough logic cells to support an 8051 core design plus a reasonable debug and test support mechanism that then in turn have substantial RAM on board are expensive parts. And then you are still be pressed to find performance based FLASH on board an FPGA.

Michael Karas