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Build an 8-bit computer from scratch (2016)

eater.net

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Re: Build an 8-bit computer from scratch (2016)

#41

Post by vhodges »

rs186 wrote: post #13

I did the whole thing, was able to get the Fibonacci numbers appear and learned a lot during the process. However, I would not recommend other people to try this today, because -- * It is not necessarily the best way to spend your time and money. You'll be looking at tens of hours on building it plus over $300 in parts, for a very slow and basic computer that you probably will forget and throw away at some point. Cut…

Yeah, I started on it and felt the same so I built

https://git.sr.ht/~vhodges/cputhing

There's

  * https://nandgame.com/
  * https://github.com/logisim-evolution/logisim-evolution
too

Re: Build an 8-bit computer from scratch (2016)

#42

Post by Cthulhu_ »

rs186 wrote: post #13

I did the whole thing, was able to get the Fibonacci numbers appear and learned a lot during the process. However, I would not recommend other people to try this today, because -- * It is not necessarily the best way to spend your time and money. You'll be looking at tens of hours on building it plus over $300 in parts, for a very slow and basic computer that you probably will forget and throw away at some point. Cut…

I was going to ask, is there anything like it where you can build a physical computer out of discrete parts? but you answered that in the last remark.

I would love a physical / homebuilt computer of sorts though. Ideally with clicking switches or lights and the like.

Re: Build an 8-bit computer from scratch (2016)

#43

Post by [deleted] »

JKCalhoun wrote: post #2

I always upvote Ben Eater's project(s). I got his 6502 kit and worked through his YouTube videos to get it up and running with LCD display and all. I want to actually frame it and get it running, hanging on a wall. If anyone is new to Ben, find a comfortable chair or couch, make some tea, take a breath, and begin your descent into his long-form breadboard series of nerd-splaining how a CPU works, beginning with basic…

[deleted]

Re: Build an 8-bit computer from scratch (2016)

#44

Post by gsibble »

I built this kit. It was a lot of fun but very tedious. I also have a computer engineering degree so I didn't really learn much. It was fun to show to people though.

If you don't understand what a register is for example though, OH MAN. You'll love this!

Re: Build an 8-bit computer from scratch (2016)

#45

Post by tmseidman »

[deleted] wrote: post #43
JKCalhoun wrote: post #2

I always upvote Ben Eater's project(s). I got his 6502 kit and worked through his YouTube videos to get it up and running with LCD display and all. I want to actually frame it and get it running, hanging on a wall. If anyone is new to Ben, find a comfortable chair or couch, make some tea, take a breath, and begin your descent into his long-form breadboard series of nerd-splaining how a CPU works, beginning with basic…

[deleted]

[flagged]

Re: Build an 8-bit computer from scratch (2016)

#46

Post by kevstev »

rs186 wrote: post #13

I did the whole thing, was able to get the Fibonacci numbers appear and learned a lot during the process. However, I would not recommend other people to try this today, because -- * It is not necessarily the best way to spend your time and money. You'll be looking at tens of hours on building it plus over $300 in parts, for a very slow and basic computer that you probably will forget and throw away at some point. Cut…

I would be shocked if anyone is really looking for anything practical out of this, its more of a lab exercise that lets you learn by actually doing things. I learn best this way. It's one thing to draw a circuit, or even put it in a simulator, but the act of hooking up the chips, and watching the blinking lights really sticks with me, and far more deeply ingrains the concepts in my head. And while the 8-bit kit is expensive, and time consuming, I found it worthwhile. There is probably a lot more value to be had in the 6502 series though, if for no other reason that the 6502 is iconic, and it was something of a thrill to me to really understand at a basic level the chip that powered the NES I spent so many hours with.

Re: Build an 8-bit computer from scratch (2016)

#48

Post by myself248 »

rs186 wrote: post #13

I did the whole thing, was able to get the Fibonacci numbers appear and learned a lot during the process. However, I would not recommend other people to try this today, because -- * It is not necessarily the best way to spend your time and money. You'll be looking at tens of hours on building it plus over $300 in parts, for a very slow and basic computer that you probably will forget and throw away at some point. Cut…

Speaking as a down-in-the-dirt circuit-slinger who works alongside a lot of ivory-tower engineers who couldn't diagnose a loose wire if their life depended on it, I think that's the whole point.

* Tens of hours and under $1000 is an extremely cheap route to this level of understanding if compared against university courses. I'd give my left nut to have my coworkers go through this process.

* Cutting and laying out wires is time-consuming and error-prone. Yup, hardware is like that. Sweeping out the dojo is menial but important. Developing an intuition around when a weird behavior might actually be a hardware problem, is priceless and absolutely essential for any embedded engineer. And you will never, ever get that from a simulator. (As much as I love the ideas behind nand2tetris, it's entirely done in simulation and that misses half the point, IMHO.)

* Sad to say, the outdated components thing is only getting worse as more basic stuff goes out of production in favor of more highly integrated components. (Even the epic VULCAN-74 caved and used modern RAM.) It might be possible to rework this project to use newer parts but keep the educational value. I suspect there's enough people who've pursued this project and done bits and pieces of that, someone just needs to unify it.

Re: Build an 8-bit computer from scratch (2016)

#49

Post by kees99 »

rs186 wrote: post #13

I did the whole thing, was able to get the Fibonacci numbers appear and learned a lot during the process. However, I would not recommend other people to try this today, because -- * It is not necessarily the best way to spend your time and money. You'll be looking at tens of hours on building it plus over $300 in parts, for a very slow and basic computer that you probably will forget and throw away at some point. Cut…

> just plain wrong -- e.g. floating inputs or missing resistors

TTL logic gates have no problem with floating inputs. Those are interpreted as logic high. [1]

This is fairly self-evident from looking at a typical TTL gate schematics. [2]

Some "TTL-compatible" CMOS parts (including 65C02) have internal pull-ups on inputs, to match this quirk. [3]

Granted, it is a bad habit to develop, given that nearly all "modern" logic (i.e. of past 30+ years) is CMOS with no "TTL compatibility", and floating inputs are a big problem there.

[1] https://electronics.stackexchange.com/questions/683051/outpu...

[2] https://upload.wikimedia.org/wikipedia/commons/thumb/d/d4/TT...

[3] https://wilsonminesco.com/NMOS-CMOSdif/

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