
Show HN: I Am Making an 8-Bit CPU in Logisim - redpanda_ua
Hey HN, 
I am making an 8-Bit CPU in Logisim and blogging about it.t&#x27;s nothing fancy, really simple, unoptimized dumb CPU for sake of learning. I am no electrical engineer, I am just a self-taught dude who has programming as a hobby and wanted to dive deeper into abstractions.<p>So here it is, so far I wrote 2 parts:<p>* <a href="https:&#x2F;&#x2F;codebite.xyz&#x2F;post&#x2F;2017&#x2F;3&#x2F;7&#x2F;Let&#x27;s%20Make%20a%20CPU:%20Part%200%20-%20Intro&#x2F;" rel="nofollow">https:&#x2F;&#x2F;codebite.xyz&#x2F;post&#x2F;2017&#x2F;3&#x2F;7&#x2F;Let&#x27;s%20Make%20a%20CPU:%2...</a><p>* <a href="https:&#x2F;&#x2F;codebite.xyz&#x2F;post&#x2F;2017&#x2F;3&#x2F;9&#x2F;Let&#x27;s%20Make%20a%20CPU:%20Part%201%20-%20In%20the%20beginning%20there%20was%20a%20Transistor&#x2F;" rel="nofollow">https:&#x2F;&#x2F;codebite.xyz&#x2F;post&#x2F;2017&#x2F;3&#x2F;9&#x2F;Let&#x27;s%20Make%20a%20CPU:%2...</a><p>I welcome any and all critique and feedback, as I can be wrong about everything for sure.
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vkuruthers
Looks like a good project, a nice change from doing everything in HDL.

Isn't the circuit layout going to get quite large however? How are you going
to organize it? E.g. does Logisim have hierarchical views or sub-components?

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detaro
Yes, it does have custom components. It gets slow with complex examples like a
CPU, but not so much to become useless.

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vkuruthers
Good plan. Have you thought much about the instruction set yet? Any
interesting features from existing commercial 8 bit processors you're going to
re-implement?

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redpanda_ua
I plan to KISS it as much as possible. The goal is to learn the basics. Maybe
after that do more cool stuff in some HDL. Maybe even buy a FPGA :)

I am a further into the development of the CPU then I show in the blog, as
such I do have ISA already, but it's constantly changing. The control bus
though, is final I think.

[https://i.imgur.com/1Sh1cSh.png](https://i.imgur.com/1Sh1cSh.png)

