Isn't a solid Vdd plane just as effective as a solid Vss plane for signal path returns? I don't know why the little engineer in my head is whispering this, but I'm not scared to advertise his ignorance if he's wrong.

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Got a kilobyte lying fallow in your 65xx's memory map? Sprinkle some VTL02C on it and see how it grows on you!

Mike B. (about me) (learning how to github)

Certainly I've seen and used the term 'virtual ground' before.

I can't feel that two ground planes is a great idea - it's going to make the power routing more difficult, at least.

And, while it's true that the ground plane is a greater distance from the top side and the bottom side, both of those distances are rather small! So it feels like a possible case of over-optimisation.

But the real answer would be in doing it both ways and measuring very carefully, and then, even if one case were slightly worse than the other, judging whether that worse case is actually important. Engineering is about judgements, a lot of the time. It's very rarely about minimising things at all costs.

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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?

Alright, quick update. My PCBs and Parts arrived. Tomorrow i will be soldering the whole thing and then report back.

i really hope this works at 25MHz. if it doesn't i'm gonna have a problem when trying to do a VGA Card due to it not being able to synchronize with the CPU.
i do have like 80kB of Dual Port RAM lying around, but the chips are massive and slow (55ns) so i wouldn't be able to do 320x200 @ 256 colors (which needs ~64kB of RAM) without the board getting very massive.
oh well i'll see how it goes. my 65C02 SBC surprised me in the past as well, being able to run 20MHz without issue.

Ah yes, this reminds me of the great expression of well-being to tinkerers everywhere: "May the parts be with you." ;-p

Good luck on your build!

well that luck didn't last very long.

today work was a lot more stressful than expected, so i only had the last 1.5h of the day to work on the SBC, i only got this far:

and most of that time was battling with the SRAM IC (SOJ package).
I honestly have no idea how i'm supposed to solder those. the pads are too small so i cannot even touch them with the soldering iron to put any solder on them (next revision will have new footprints with longer pads), and putting solder on each lead won't work either as it doesn't just flow down towards the pad.
i tried the flooding technique i read somewhere on here (where you hold the board vertical and drag the solder downwards with gravity) and while that it somewhat work, a lot of leads were still not connected and i had some solder stuck between 2 pads where it was really really difficult to remove from. (maybe i didn't use enough solder? not sure)
I only have a regular soldering station with a few tips. i do also have a hot air gun, but nothing to hold the IC in place while blasting it with air (plus i have no soldering paste)

so what's the trick with these? i would really like to continue using these SOJ SRAM IC in the future due to their speed and capacity, so i'm hoping there is a way to do it more easily.
and would larger/longer pads actually help (though i won't be ordering new PCBs just yet, i still want to get this one up and running).

some close up images (i only have my phone with 8x zoom, so they're pretty blurry):

_________________
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?

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

I agree with the BDD's comment about needing larger pads so the soldering tip has a landing zone to make good contact with pads. Standard SMT library is for machine soldering so the pads are too small, you need to make a custom library for hand soldering. Many times I've observed PCB assemblers do drag soldering, but I'm too chicken to try it myself, so I still solder one pin at a time. Like BDD, I solder the corner pins first, apply liquid flux over pads and pins, then solder one pin at a time with fine solder tip. Picture shows both the SMT pad size and the fine, curved solder tip I used to solder SMT components.
Bill

I found that thin solder (0.38mm) really helps with these. I set my iron tip on top of the leg to heat it up, and insert the solder between the pad and the leg. It works really well. I use the standard KiCad footprint.

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BB816 Computer YouTube series

Welp my bad luck continues as I have apparently killed the soldering iron at work trying to do the solder flooding technique.

Now instead of showing the temperature the station just lights up all the displays elements until I disconnect the iron from the station, how does that even make sense?

(The manual doesn't mention anything like this either)

Oh well, I'll have to order a replacement iron before anyone at work notices (because then I'd very very likely lose my soldering privileges, and I don't have the space for my own iron at home yet)

Before it died it did have some real issues keeping all the solder molten, its 80W but I wonder if the GND and Vcc planes sucked away too much heat for it to keep up, so it just died...? I'm not sure.

Either way before I got a new iron I won't be able to continue on this.

_________________
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?

But it's only 2 years old and wasn't used much within that time (I use it the most)... so it still seems strange.
How long do decent soldering irons usually last compared the station itself?

Your VCC/GND thermal relief spokes maybe too wide if the solder is not melting easily around the VCC and GND connections. The trace width of spoke should be 0.010" or less.

I bought my Metcal soldering station used 20 years ago. Used it frequently and have replaced the tips 4 times during the 20 years.
Bill

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