(ah yes, I forgot mouser - I haven't used them but they have a UK operation.)

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

In addition to this advantage, the Pi is inexpensive and has more I/O than today's PCs, which typically lack a parallel port.
(But really, it would be better to promote what you think is a good way to do things, rather than rubbishing someone else's choice.)
Cheers, Ed

Exactly. I've never made a 6502 board from real hardware, but I have made a version of a 6502 computer in an FPGA, all the way down to the 6502 core itself. For my work, I use a lot of ARM devices, that literally only need 3V3 power to turn into a functioning 'computer', but I may add an external Ethernet port and SD card and write all the software to make them work. These are all completely different challenges, but each of them teaches something worthwhile about computer design.

Good debate! I agree with those who claim that the Rasp Pi might not be challenging for many but keep in mind it's an entry point, a lowered barrier to technology. Most people use technology and consume on a scale that I'm scared to even think of what the world will be like in 50 years. Yet, they don't understand how things work. I call it the 'alienation from technology'. We use it but don't understand it. The consequences will be (are) catastrophic: 80% of the products sold in the UK end up in the land fill in 6 month. From this point of view, Arduino and the Rasp Pi are great, they attract people who don't have the time, money and energy to learn about computing and turn them into makers. Or at least, they get an idea of how things work. I started learning programming when I bought my Arduino. I remember how exciting it was to be able to turn a LED on!
On the other hand, indeed these new devices are very easy to use but 'hide' what's under the bonnet. That's why I think it would be a great idea to have a DIY SBC kit. That could be the next logical step: after learning programming an SBC or a MUC, build a computer and master it! The Apatco one is great but not portable. It would be nice to have something like that but permanent. Such SBC could also serve as a basis for expanding the computer and learning about programming.

Kudos! FPGAs are fantastic. If only I had the time to learn more about them, I have one but need to learn more... Somehow my simulations never work (Xilinx), whatever I design.

Good stuff, thank you!

Maybe not, but if you have access to a vacuum pump, it isn't very difficult to make triode valves (or vacuum tubes as our american friends like to call them.), as I actually did whilst taking A level Physics. I'd hate to have to make enougth of them to build a working computer but I wouldn't be surprised to find there is someone out there who is prepared to do it! Sounds to me like the ultimate in home-brew computing.

I have to agree that assembling your own computer from individual components is far more satisfying and educational than assembling a PC from pre-assembled modules. It is also far more frustrating as well!

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Shift to the left,
Shift to the right,
Mask in, Mask Out,
BYTE! BYTE! BYTE!

Here's a nice video of Claude Paillard hand making vacuum tubes: http://www.youtube.com/watch?v=EzyXMEpq4qw

And here's a relay computer: http://www.youtube.com/watch?v=n3wPBcmSb2U

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

Years ago I read an article about sputtering your own transistors.
I don't recall what was used, but pretty sure it wasn't Silicon.
I think it was in the amateur scientist in Scientific American.

Isn't germanium easier to deal when making primitive transistors?

If you want to go hardcore, you can build your own valves, as mentioned and make all of the resistors, coils and capacitors(paper and oil), and then build the computer. Or mechanical, like Babbage's Difference engine...
But i guess you would spend like 10 years, and you would get something that is more of a peace of art that a device. I think the lowest that it is sane to go is down to ttl/cmos gates or relays(but that already is more art than machine).

Don't really remember, but believe he tried several things. Though I can't remember
specifics, my recollection is that it was much more mundane stuff like copper oxide or
calcium carbide or something like that.

If it were me, I think I'd try magnetic reed relays.*

I always wanted to to build a calculator out of tinker toys.
(never could figure out a reasonable way to make a gate)

*my cousin and I built a four bit binary adder when we were in
junior high. we felt very clever using counter windings to form an
XOR gate

I remembered, before i even tried to solder a transistor, in some of the final grades of elementary, i found this old board with relays on top which made some sort of array, back then i didn't really know how to make a full adder, but i knew that such a device existed that could add binary numbers. So i went and i started soldering them with no clue how exactly should i connect them, but after a while i found a way to wire them up to act as a full adder . I think it was 3 bit.
And later i got another array of relays(each relay had 3 separate switches), and then i connected them so that when one relay was activated, it would activate the next, deactivate the previous, and keep itself active. So when started it would run in a loop, and i added led diodes so i got a running light that suck lots of power, and made a lot of noise(my mom actually complained about that). After that adventure i finally decided to give a try to the mythical transistors and their magical properties.

Years later i was planning to build a small relay computer, i actually estimated how much relays i would need, but i never had the money to buy them. So that didn't get very far. Maybe one day when ill have more money i could to try to implement that minimal cpu of mine which is giving me headaches because it won't fit in the xc9572, so i still need to fit it somehow(i was thinking of using a third cpld for instruction decoding, that might solve the problem).

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x86?  We ain't got no x86.  We don't NEED no stinking x86!