I'm not an expert, but here's a thread to collect expertise...

We've seen comments about how anything up to 1MHz is fine on a breadboard, maybe a bit more. But WDC's chips are specced up to 14MHz and can go higher, and FPGA designs can go at 50MHz with older 5V parts and over 100MHz with newer 3V parts.

What are the considerations for a working circuit at progressively higher speeds? Here's my take:
- bypass capacitors near all power pins of all chips
- preferably use a ground plane (consider the return current path for each signal, and minimise the area enclosed by the whole path because it is an antenna)
- certainly fat power wiring (possibly in a star topology?)
- signal traces should be direct, and short (place components near each other)
- signals should be well spaced if possible
- signals should be interleaved with grounds (in cables and connectors) or should be close to the nearest ground
- can often consider a power rail as a virtual ground
- avoid sharp bends and overshoots: clip wire ends back to the pins

I can't see that there can be any hard limits as to which clock speeds mandate how much care you need: you only need to take enough care to make the circuit fit for purpose(*). Take too little, and it will let you down. Take too much and the project is harder than it needed to be. Therefore all the above rules are qualitative.

Cheers
Ed

(*) The Apollo Guidance Computer clocked at 2MHz. It absolutely had to work, for PR and for human lives. A one-off hobby machine, not so much.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Thanks for the info and for all those links!

I'd like to add (another) recommendation for http://electronics.stackexchange.com - in this case, perhaps this is a good example, which recommends Johnson's book and contains a lot of detail besides. The 'tags' are useful for finding related Q+As.

Another post there recommends Eric Bogatin's book - some of which can be read as a preview on Amazon, enough in fact to give some idea of what the issues are, why they arise and why they are a problem.

Edit: Douglas Brooks also has a recommended book, and many articles online

Edit: fixup dead links

When I got back into WireWrapping a couple years ago, I remember looking for a WW gun. One similar to the one I'd used over 20 years ago (my dad had one lying around). Most prices of 120V guns were and still are $150+ if one does a simple Google search. I refused to pay that. So I decided to dig up some info now and share the model that I had bought for <$30. I was very happy with what I got and wonder to this day how some of these other mainstream distributors get away with charging so much more for the same product.

For those interested in starting to prototype their projects in Wire Wrap, Search EBay for: Gardner Denver wire wrap
You'll see some guns for cheap...
You'll also have to buy some appropriate gauge sleeves for the size wire you're using, not to mention the wire. I would also recommend a pair of fine tipped wire cutters, and an un-wirewrap tool.

If any of you have started out your projects using soldering/breadboard methods and switch to WW, you will see why more than one of us recommend wirewrapping for high speed prototyping!

Here's another thread worth reading through about WW adapters if you get deep enough into a WW project and you have to use today's SMT technology.

EDIT: I almost forgot to mention the wire strippers. Since it's not to easy to manually strip off insulation from 30AWG wire, they make automatic ones and they're not too expensive. The one I bought a couple years ago off of Ebay is called a Stripmaster, and precisely removes about 1 inch of insulation from 22,24,26,28,30AWG WW wire. It does not 'dig' into the conductor.

Nope, I've never seen PLCC adapter sockets without the PC board adapter...

Why not just tear apart some old WW socket/s to get at the WW pins individually and then mount them on the PLCC socket?

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Let me add this link of a conversation between me and the Commodore 128 hardware designer Bil Herd to this list: http://www.6502.org/users/andre/icaphw/design.html
It talks about DRAM and other timing- and power supply issues.

André

I was reading about breadboard limitations and wanted to give the links that may be a benefit. They think that there is a 50 MHZ limitation.

http://dangerousprototypes.com/2011/12/ ... mitations/

http://dangerousprototypes.com/forum/vi ... 210#p31532

We should compose a list of prototyping methods and their limitation.
Like: Point to point soldering on perfboard, ww, ect...
I an interested what is the max frequency possible when using point to point soldering on perfboard(because i use it mostly).

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Why bother put yourself/or anyone else through that?
You'll hit a brick wall at some point in your project and it is guaranteed to involve more than 1 variable using your soldering technique.
Just in case you/or anyone else hasn't read the wiki for wirewrap, it is some good reading. This is all I have to offer on this topic.

Good Luck

P.S. Don't let that lead get to your head!

See this pdf on power supply design

Hi.

I don't have any proper recommendations, just my own experiences...

I find 74LS to be more reliable than 74HCT on breadboard. I think the HCT tend to have a faster rise/fall time which causes more noise on supply lines which tend to be daisy-chained over many connections when powering chips on breadboard. The vertical contact nature of breadboards make good capacitors between tracks at high frequencies/fast rise times

I've got CPUs (Z80's mainly, but applies to most, I would have thought) running at 10MHz or so on breadboard without much issue, though.

It is possible to do a large computer design on breadboard, though with regular decoupling.
Here are a couple of my breadboarded computers...
http://home.micros.users.btopenworld.com/cpm/index.htm
and
http://home.micros.users.btopenworld.co ... mClone.JPG
The spectrum clone shown above used HCTs and was a pain to get working reliably. You can see in the photo where I connected the power. If I moved the power connections to some other areas of the board then it would crash.

I've also done 6502 computers on breadboard, but admitidely at lower speeds.

CPLD (in adaptors) seems very unreliable on breadboard - they have fast switching and are therefore prone to short spike noise from adjacent tracks.

I've tried a sheet of aluminium under the boards connected to Gnd with no clear difference in reliability.

Regards.


Grant.