Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Build an 8-bit computer from scratch (2016)

eater.net

Post reply on HN
Print view View original

31–40 of 68 posts

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

#31

Post by brucehoult »

johnklos wrote: post #25
brucehoult wrote: post #12

Note that even the "Update" video is nine years old. Also note that yes it's a computer, but it has 16 bytes of memory to hold both the program and the program's variables. BYTES. Not KB, not MB, not GB. Bytes. The demo Fibonacci program is pretty much the most complex thing you can do with it. But it is in fact a genuine von Neumann computer. And understandable.

It feels almost more useful than BASIC on the Atari 2600, at least.

The MOS 6532 RAM-I/O-Timer chip used by the 2600 (and KIM-1 and others) has 128 bytes of RAM. Game cartridges could add 256 bytes more, along with the program ROM.

For an experience today closer to these machines, you can get a $0.10 CH32V003 microcontroller with 2k RAM and 16k flash.

Here's a 1 Euro retro-computer kit using one that has included in that price support for PS/2 keyboard and VGA video output, all included in the 1 Euro -- even the connectors! All from one 8 pin microcontroller chip:

https://www.olimex.com/Products/Retro-Computers/RVPC/open-so...

https://www.youtube.com/watch?v=dfXWs4CJuY0

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

#32

Post by asdefghyk »

RE "....Cutting and laying out wires are some of the most tedious and frustrating process....." I would be investigating to use wire wrap. I built some circuits using wire wrap, back in late 70s ,early 80s. I designed and built a circuit on a wire wrap prototype board to put a 68008 DIL chip on the Apple II bus. I'm not sure of the cost of wire wrap parts now - may be quite expensive , the special wire wrap sockets etc .....

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

#33

Post by asdefghyk »

apricot wrote: post #6

Ben Eater's breadboard CPU is a good way to learn the basics, but since the focus is pedagogical, it's very underpowered for the quantity of chips it uses (and you better enjoy forming wires). For a much more powerful computer built around the same number of TTL chips, see the Gigatron.

RE .... See the Gigatron. Google link https://www.google.com/search?q=Gigatron+CPU&oq=Gigatron+CPU gives lots of good explanatory links . (I had never heard of it , it looks quite interesting .... )

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

#36

Post by asdefghyk »

bionsystem wrote: post #24
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…

As a side note, reading "But How Do It Know" for a total beginner like me can help to scratch the itch of understanding the basics. I really loved the book and will buy my 3rd copy (lost one and gave away another).

Another popular book "An introduction to microcomputers" by Osborne, Adam, 1980 also has great detail on this topic..... Its on the internet archive https://archive.org/details/introductiontomi00adam/mode/2up

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

#38

Post by hydrolox »

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…

Although I haven't followed his project at all, one fully free alternative which gives similar insight (how logic gates build up to a full computer) is the nand2tetris[1] course. It starts with just a nand gate and then creates all necessary components to make a simple programmable computer, all simulated virtually so you don't need any physical components.

1. https://www.nand2tetris.org/

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

#39

Post by hydrolox »

schoen wrote: post #15

Wasn't there someone who did a physical discrete logic implementation of the NAND to Tetris design? I feel like that could be a good choice for someone doing this today because there's now a kind of a large ecosystem of resources for that design (not that it's inherently better somehow).

yep https://youtu.be/L-azf9ecvfo

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

#40

Post by imglorp »

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…

An alternative might be to write or find a gate level simulator, then write a library for each IC like hex inverter, quad nand, etc. Then you could pick up where Ben starts at the pin level, without messing with wires and breadboards, and get much of the same understanding.
Post reply on HN