I realize in looking over everything I'm doing for this project, it's actually several projects that are falling under one umbrella. 

• A TTL design (which is only at the design phase)
• An FPGA design (which is fully working)
• An assembler (which is fully working)
• Software code development to implement macro-functions which emulate normal architecture instructions (significant development)
• Software code development to implement more advanced features like a stack and ASCII conversion
• Emulated hardware on a PC for easier debug (not started)
• Emulated hardware on a PC as a video game (not started)

Each of these can be a separate project.  Looking over other projects, some people's whole project is to develop an FPGA microprocessor which is only one component for me.  Considering I have very little time/energy to devote to this project, I need to decide which components to focus on.

However, there is an underlying commonality which is the architecture.  All of these assume a similar architecture even if they have different implementations.  The FPGA doesn't use tri-state buses, but the TTL circuit does.  It doesn't even matter if the TTL version has a single source/destination bus, and the FPGA has two separate ones, or even if it's emulated hardware.  As long as they can all execute the same code, then I would say they are the same.  I have to admit, I'm pretty happy with the FPGA version because I can change it very quickly and have decent debug capabilities with the simulator.

I guess what I'm saying is I may delay building the TTL version for now, but keep the design so it can easily be built.  I'd like to focus on developing the software and run it on the FPGA.  The software development has been a lot of fun, which is why I keep thinking about making a video game about it similar to Human Resource Machine or the Zachtronics games.  If only I had more time/energy, but my priorities are family->work->hobbies, I'm left with maybe an hour a day for the last one and no energy.