glauxosdever wrote:
As for your CPU, I find it quite interesting. In what language/program did you design it? Do you have some test programs for it?
Too bad however you limited it to 16-bit.
I missed this because the thread was moved, sorry.
I never actually produced a completed design for this CPU because I wanted to be able to interface with standard peripherals (VGA, PS/2, floppy disk or even IDE hard disk) and the design of those held me back. I had already produced and ran in a simulator a "proof-of-concept" 8-bit design of a completely different and rather inelegant architecture just to prove that it was possible for me to design and implement a CPU. That was actually quite an amazing experience, seeing how hardware and software fitted together at the very layer where they meet, and was something that I didn't really understand before (I understood the concept of a CPU but the whole thing seemed a bit like magic to me, to have a device that could take software, something that's non-physical, and turn it into physical outcomes). CPUs are actually pretty fascinating devices.
My design isn't limited to 16-bit. I was originally going to build an 8-bit CPU but decided to extend it to 16-bit because 256 bytes of memory seemed far too restrictive and I didn't want to have to deal with paging or a 16-bit address line on an 8-bit CPU (I know the 6502 managed this somehow but it was too complicated for me at the time and I still think it's rather messy). I extended it to 16-bit because it seemed like a good compromise between complexity and functionality, but in the end it proved too expensive to build. The actual design however is very modular and can easily be extended to any number of bits (and extra bits means more bits are available for encoding the source and destination registers for each instruction which means more registers are available and more complex features could be mapped directly to "virtual" registers as with the ALU in the original design).