I would like to share a link to a collegiate-level course which shows how to construct a computer, assembler, compiler, and virtual machine in 12 steps, beginning with NAND gates and working upward. This course is actually taught at Harvard (and elsewhere), and the online version is available to everyone. I found the introductory video (as well as the approach they take to teaching this stuff) to be very interesting and am probably going to buy the accompanying book, "The Elements of Computer Science" (although you don't have to).

Here's a link to the site: http://www.nand2tetris.org/

Wow! That looks interesting. I wouldn't mind knowing more about the Nand2Tetris computer architecture, but I'm not sure I want to take the course in order to find out.

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Thanks for sharing, that looks really interesting

It looks interesting. Thank you for sharing this.

It would be interesting to see someone put it into FPGA and to design their own processor.

AFAICT, it is very simple indeed. There's a data register, and an address register, and a 16 bit ALU. There's a conditional jump. See slide 29 here:
http://www.nand2tetris.org/tutorials/PD ... torial.pdf
(Via http://www.nand2tetris.org/software.php)

They start by making logic gates, so the CPU needs to be simple. They construct a VM on top of this simple machine in which to make more complex programs.

I might buy the book, I see copies for around $20.

Hi, Rob. As far as I can tell, you can go through the course for free, but there wouldn't be any academic credit. The web site has an abridged version of the book broken up into chapters that you can download. In my case I just DL'd them all and combined it into a single file in Acrobat, but you could certainly do the course one at a time. The professor stressed in the video intro that the chapters are independent of one another, and that they have all the materials right there online in case a person didn't want to actually build the project.

I read through their syllabus and several chapters of information. It's a good course and uses VHDL and a simulator instead of real hardware. It will be interesting if someone builds physical hardware that can run their software.

A few years back I watched Harry Porter's videos on his relay computer, and read his design materials. After reading them I really appreciated how hardware worked. Some day I want to build a computer from scratch like that.

There is a video online showing a port of the CPU to an fpga. It's in Chinese with an English gloss. Not sure if there are sources.

This may fit somewhere in this post as useful or maybe it belongs in Logic.

Designing a CPU in VHDL, Part 10: Interrupts and Xilinx block RAMs

http://labs.domipheus.com/blog/category/projects/tpu/