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Comment by msarnoff | Hacker News Reader

Wow, never thought I'd see this posted here! (I'm the creator of this project.) I thought about building my own CPU from relays and/or discrete logic (I met the creators of the Magic-1 and BMOW a couple years ago at a Maker Faire), but it would have taken way too much time and money, so I stuck with an off-the-shelf chip.

My development process isn't that well documented online, but soon I hope to start a blog where I explain how the whole thing works; address decoding, bank switching, assembly programming, etc. And then I'll write some games, add a Forth environment, hook it up to the internet, who knows. All my source code, schematics, and tools will be online sometime in 2011 if anyone's interested.

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Forth was my first thought when I read the article -- it seems like a perfect fit for a project like this.

Can I get a pointer to why?

The 6809 actually has two stack pointers, S and U. S is the hardware stack (used for calls/returns) and U is basically another index register with dedicated push/pull instructions. A Forth implementation typically uses two stacks (the return stack and the parameter stack), this maps very well to the 6809's register set.

Here's the first of a great series of articles from 1993 about implementing Forth on 8/16-bit computers: http://www.bradrodriguez.com/papers/moving1.htm

I read on your webpage that you go to HSC. I LOVE that place.

Amazing job. This is exactly what I'd like to do in a couple years. I will definitely use this as my inspiration / guide.

A couple of really good books I'd recommend (for the intel 8086) would be the "The 8086 Project book" and the radio shack "Understanding Digital Computers".

Those books are a great start to this kind of hobby.

My library used to have the 8086 project book. When I was young I used to drool over the projects in it for hours but I never had the resources or the knowledge to build anything. I might have to check it out again now that I have both.

For those of you in the Valley, you can find the book that started me on this project at the Santa Clara library. It's the first edition of "Microprocessor System Design Fundamentals" by Kenneth J. Breeding.

It's not a great book, but it's one of very few publications (apart from the databooks) that explain the 6809 architecture.

Is that a HP1650A I spy?

Yes it is. Got it on Craigslist, ridiculously cheap, with a full set of pods and manuals. Making a boot floppy, on the other hand, was a bit of a challenge. Thanks to WeirdStuff Warehouse for still selling 720K floppies!

Being a sucker for retro I went for the green screen 1630A myself. Plus the 1650As go for hundreds of pounds here in the UK.

I like your twitter image .. I used the same one (but from my 1630A) :D (http://twitter.com/andrew_rose)

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