I've just completed what I consider my first "serious" project, a hexapod robot with main processor and coprocessor, board home-etched using Eagle design, handcrafted 4-bit aynchronous serial data bus, and it's really cool, trust me. 8^) So, wrapping this up, I'm already thinking about my next project.

My imagination was sparked by this photo:
http://en.wikipedia.org/wiki/File:YUNTEN.gif

I'm wondering if building a computer from scratch would be fun. I'd like to build one that I could actually do something with -- an 8-bit machine with a tiny BASIC or tiny FORTH interpreter in ROM for example -- not a 4-bit school lab kit.

I've seen some design ideas online around the 74x181 ALU and wondering -- has anyone traveled this (probably perilous) road? Would anyone like to team up?

If it helps to shape your answers, I'm a 30-year software veteran, not an electronics guy, and am learning this fascinating stuff in my free time. But I've come a long way from the single blinking LED in the last six months and am hungry for something new and hard to do!

Joe

 

I'm wondering if building a computer from scratch would be fun. I'd like to build one that I could actually do something with --



hi i like your idea.
yes you can build your own computer but from a scratch that's better actually computer motherboard is made up of IC's hub's and IC's are made up of Transistors..............
then why not from extremely scratch
start with transistors
best of luck

 

need guidance in direction for new project
its good
first think about the project
collect all the information about it
draw a rough design
collect the component of your design
assemble the ckt.
that's it
your project is made
best of luck
keep thinking & making

 

Where's robot?? That's much cooler than the picture you posted a link to.

Present robot plz.

 

When I was taking my CIE course, part of the course was to build a 4-bit micro using an ALU and registers. An 8-bitter would need twice the chips, but use the same clock pulses. Is it do-able? Yeah. Would I want to do it again? Considering the limitations, I am not too sure.

If you'd like, I may be able to dig up the book and copy the schematics for the project -- this was the early 80's, so personal computers were a pretty new thing (no PDFs, scanners, etc.).

--Rich

 

I'm new to this forum, so I was looking last night at the presentation in the "projects" pages. I have a few photos of my robot to share, and will try to get them posted soon. I even have a short video -- hoping to get it on youtube soon.

 

I'd not choose to build using transistors as mkbutan suggests. I'd want to (at a minimum) use SSI and MSI packages. The 74x181 looks interesting, because it integrates ~70 logic gates into a convenient package.

I've also wondered about building around an existing CPU, like a Z80 or 6502 or something, but that would mean less "invention" but more stuff available for free -- like supporting software. I'm wavering, for example, if I really want to create my own assembler to program this thing....

 

If you were going to build from component level, I'd take a look at the DEC PDP8 instruction set.

As these machines were built from discrete components, it's quite minimal (just eight instructions) but well oranised and plenty of software available.

(The later PDP8i was the Integrated Circuit version, using early, simple logic ICs)
Lots of info here: http://en.wikipedia.org/wiki/PDP-8

 

Eight instructions? Wow. That's amazing. I learned a tiny bit of assembler on the Z80 when I was in high school -- pumping up basic programs with assembly for speed -- and the Z80 had MANY more than eight instructions. So that fact alone is amazing to me.

The wikipedia article was interesting for sure.