Jan Gray is, I think, more-or-less the Godfather of this approach. I especially enjoyed his Circuit Cellar 3-part series where he describes and builds the xr16

Jan Gray is, I think, more-or-less the Godfather of this approach. I especially enjoyed his Circuit Cellar 3-part series where he describes and builds the xr16 -- a 16-bit machine whose instruction set is designed to well-match the LUT capabilities of an FPGA. I implemented it, and with the LCC C compiler, I was able to run plenty of code. Start here: https://github.com/BigEd/XSOC-xr16/blob/master/doc/xsoc-talk.pdf https://github.com/BigEd/XSOC-xr16/blob/master/doc/xsoc-talk... which is the presentation; then check out the rest of the repo doc: https://github.com/BigEd/XSOC-xr16/tree/master/doc https://github.com/BigEd/XSOC-xr16/tree/master/doc and although it's not maintained these days, his old site is also useful: http://www.fpgacpu.org/xsoc/xr16.html http://www.fpgacpu.org/xsoc/xr16.html for more modern stuff, see http://fpga.org/ http://fpga.org/