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Building your own PC from scratch (?)

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DreadStorm

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Has anyone ever considered the idea, be it in the past or recently, of building a complete computer system for themselves from scratch?

I don't mean a dedicated single-purpose, or limited function machine. I mean something along the lines of an Atari, a (later) Commodore, or even something as powerful as an Amiga or early Mac.

I'm asking this because I've had a nagging idea in the back of my head for decades now. And the more I play with my machines, and tinker with MS Visio (that helps me set up my things) the more I think that I still want to go through with my early ideas from years ago.

Granted, there wouldn't be any market for something like I want to build, but it would still give me enormous satisfaction to have it made. I still remember most of my "plans", and recently began knocking out some notes and sketches.

I'm wondering how many of you have kicked around the same general ideas? Did you succeed? What's the basic architecture? How is it used (GUI/text/BASIC)? How is it expanded? That sort of thing.

If interested, I can post some notes that I've recently re-planned. I'm thinking that, if I get rich someday, I might actually go through with it, and have it built - if for nothing else than to keep me busy when PCs bore me.
 
Hi,
I am doing that very thing right now. Last year I built a Z80 home brew computer completely from scratch. I mean, starting with some notes and a protoboard, soldering iron, some chips and a VOM, built a working CP/M computer.

It was a lot of fun getting it to work and watching the design evolve. At the present, I am revisiting the design and repackaging it with a commercially produced PCB. It is a *lot* of fun and extremely educational.

I recommend it! Thanks and good luck!

Andrew Lynch
 
I was thinking along the lines of something like that. I'm going to try to put together a DOS-style machine, with an optional GUI (as I practice programming) as well. I was kicking around using an '030 chipset, so I can use megs of RAM, expandability, and so on.

By DOS-style, I mean it operates off something like the common features of CP/M, MS-DOS, ProDOS...In a similar fashion. Keyboard's a little different, and once I study up on Motorola's architecture, I'm going to try to (wing it) make some schematics. heh

To be honest, I know I'm jumping in over my head by a long ways, and I could use some help with it. But as it is so far, I'm going to do what I'm able, and wing it with the rest, until I get to a point where the help is absolutely necessary.
 
My advice would be to start with a much simpler architecture than a 68030. That is going to be a very complex and difficult to build machine. If you are certain you want the Motorola architecture, then I would start with the 6809, 68HC11, or something simple like that. Find a good example circuit on the internet and build the machine.

There may be some good 68000 circuits available but anything that uses large amounts of RAM is going to likely require DRAM and that is an advanced topic due to its peculiar electrical characteristics.

I'd start small with something achievable and work up from there. There may be some homebrew 68000 circuits out there but I will assure you they will be much more complex to build than an 8 bit machine. Due to the wiring complexities you'll almost certainly have to go with a manufactured PCB for the 68000 machine since the wire wrap and protoboard approach would be pretty tough.

Best of luck!

Andrew Lynch
 
Please don't think I am trying to "throw cold water" on your idea, it is perfectly legitimate. There *have* been successful 68K based homebrew systems. Do some Google searches on the "Applix 1616" and you'll see quite an impressive system they did in Australia by Andrew Morton no less.

Also, there is an O'Reilly book called "Designing Embedded Hardware" with some good example circuits for 68K which don't appear to be *too* bad although they are still going to be more complex than an 8 bit CPU based machine.

http://books.google.com/books?id=Ko...mple+68000+circuit&source=gbs_summary_s&cad=0

Thanks and good luck!

Andrew Lynch
 
I wasn't taking it as that - common sense tells most people to start small. Unfortunately, I usually end up jumping in with both feet, and then floundering. heh

As I think about it, though, I was revising my ideas. Wouldn't a Z8000 be more practical?
 
Hi
I've seen various levels done. Resently I've seen a few that created
there own processor. In one case it was using programmable logic
arrays. Most were using piles of TTL parts.
One could model it after a known processor or step out of the
norm and create ones own architecture.
I've always wanted to do a bit serial processor. Most operations
are just handling flags. I was think of having a separate arithmatic
unit to handle thing like adds/subtract/multiply/divide. The main
processor would only be dealing with flags and such.
One can still limit one self to known proessors such as the 68K but
this seem dull to me when one can play with all kinds of thinking.
Dwight
 
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