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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?

Good catch about the power/ground traces. They absolutely need to be wide traces and forming a grid, especially the ground. The board is unlikely to work in current implementation. If the boards are already in fabrication, you'll need to solder additional ground wires from CPU to RAM, EPROM, and decoding logic. That'll at least get the board to power up and then you can use the board to troubleshoot rest of the circuit. Fortunately, the RAM and EPROM are slow parts. Use the slow old CMOS 65C02 if you have it. WDC's W65C02 is much too fast and noisy for this board design. Good luck,
Bill

plasmo - it’s not to late. Is it better to just have a solid inner GND and VCC plane, making it 4 layers? It’ll cost more but that’s not an issue. I’d rather do it right, that why I’m here… to learn :)

Yes, 4-layer pc board is the safest approach. It is also easier to route because power/ground are pre-routed in the inner layers.
Bill

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

It was BDD who convinced me to use 4-layer boards as well. And I am very thankful that he did! Honestly I probably couldn't design a 2-layer board correctly at this point, because I'm very reliant on the inner VCC and GND planes. Routing is so easy and I have confidence in it's reliability. Because of the enormous cost of larger 4-layer boards, I refuse to go above the 10cm x 10cm mark, ever. If it doesn't fit, then I need a second board or I didn't need that feature to begin with. Just my way of thinking, that's all, I try to be super frugal.

As per that sticky topic on high speed design: I just went through it myself 2 days ago. The whole thing. And there is good information there, but honestly it's so congested and hard to comb through. There are SO MANY links and tutorials and videos and information there, but getting a straight answer through it is a bit hard. On top of that, we all seem to have different opinions on specifics. If we are recommending outside links, I would recommend EVERYTHING from Garth Wilson's 6502 Primer pages. Literally gold.

Chad

4-layer pc board is like apple pie and motherhood, especially if it is affordable and nowaday it is. I am moving toward 4-layer boards as well, but looking at 57 board designs I did in 2019, 58 designs in 2020, and 25 designs in 2021, I can only find four 4-layer designs, all done in later half of 2021 when 4-layer pcb became affordable. The other 136 2-layer designs worked just fine, except one 68020 motherboard with 16-meg dynamic RAM that generated excessive refresh noise which was promptly fixed with a 4-layer design.
Bill

I'm not opposed to four-layer, but there are both pros and cons to be weighed.

Yes, routing is somewhat easier, because about 10 or 15% of your traces go away. Not that big a deal, IMO, although admittedly the traces that go away (ie, Vcc and Ground) are the ones that are more difficult for a novice to do properly -- I mean "properly" if good AC performance is required. But this excludes many novice projects.

I'm not opposed to using a second board, either. But once again there are both pros and cons.

I see Bill (plasmo) has posted while I was typing, and I echo his point that a two-layer board is usually entirely viable.

-- Jeff

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In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
https://laughtonelectronics.com/Arcana/ ... mmary.html

I'm just sharing my personal thoughts on the matter. Indeed there are pros and cons, but at my stage, if it doesn't fit on one board with auto-router, then I'm probably allowing feature creep to set in. Heck my third board coming soon has PS/2 Keyboard, a SNES controller port (which is hunkin' huge), and tons of plug-and-play ports.

And of course this is coming from the guy who refuses to spend $40 on a EPROM programmer, no more than $8 on a board, yet will spend over $100 on chips! Take it with a grain of salt.



Bill, I didn't know you were so... prolific!

Chad

It is prototyping with PC board, JLCPCB and Seeed Studio make it possible with fast turn and cheap boards. DHL shipping is the real winner, however.
Bill

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

Hi again :)

I've been reeding the "Techniques for reliable high-speed digital circuits" sticky. There is a ton in there and I'm trying to grasp at least some of it. I also learn a lot by doing and getting feedback, so this is my current PCB setup. I split each layer out. Have I made any glaring mistakes?

_________________
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?

I'll set the GND plane clearance to 0.254mm so it goes between all the pads.