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Comment by mysterydip | Hacker News Reader

Wow! Thanks for making such an interesting and detailed writeup! And using my favorite CPU too :) Definitely bookmarked to read through more times.

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Z80 rules!

Thanks :)

I love that there is a group of people who still love the Z80!

Such a beautifully designed chip.

I was doing a little bit of Z80 work a while back, but I didn't particularly seem to appreciate its design (compared to say MIPS). Why do you think it's beautifully designed?

You can hand clock a Z80. There is a certain magic to that.

I'm sorry, but what does "hand clocking" a Z80 mean?

I think GP's use of "hand-clocking" to refer to the factthat the z80 can run on a very low clock rate, to the extent that you can have a hand switch that sends individual clock pulses to the processor. This can be useful for testing purposes as well as for low power operation in embedded applications.

http://www.thomasloven.com/blog/2013/01/Z80-Tester/

As the Z80 doesn't use dynamic registers (I think basically the only "modern" CPU to make this decision) it doesn't need a minimum clock signal speed to refresh the registers as every other CPU does.

This means you can rig up a push button switch and manually advanced the clock one button press at a time.

To me that's super cool. It also makes them really easy to debug.

Admittedly, I do not have a lot of experience in other CPUs, but to me its just the way its designed. A simple syntax for assembly and the way it maps to byte values is clever. It doesn't require a lot of work to make things happen, ie "hacks" for interacting with IO. I also like how there is a separate IO bus from the data bus, which means IO doesn't take up memory. The register naming convention is simple, and having "alternate" registers is cool.

Just seems simple and cool to me.

Out of curiosity, have you thought about trying to port "real" games over to it, as in running a ROM of something commercially released? This is already really cool, but it would be nerd-cred-for-life cool if you could say "Oh, you have a gameboy? Yeah, I built my own."

I used to do Z80 programming in the TI-82 in high school back in 2002. This seeing the code in the article brought back some good memories.

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