[Coco] MC6847 VGA (FPGA) Project underway...

[Zippster]

No problem with comments… :)

- Ed

> On Oct 11, 2015, at 6:06 PM, RETRO Innovations <go4retro at go4retro.com> wrote:
> 
> On 10/11/2015 3:49 PM, Zippster wrote:
>> Sneak peek of the layout for American CoCo2 motherboards…
>> Still needs some work, but pretty close.
> 
> You didn't ask for comments, and obviously I'm not laying out the board, so take all of these with a nice big crystal of NaCl:
> 
> * No way to hide IC2/3/4 under the 6847 header footprint?

Way too tight for fanout and signal routing.

> * I'd put the switches on the let, flip the VRs under the board and
>   move them closer to the FPGA.  That would elim the dog ear.

I considered that, but there’s plenty of room in the case, and the minor
increase in board cost from the dog ear doesn’t bother me.

> * Looks like rotating the FPGA 45 degrees would help with layout.

Maybe, that’s just the way I laid it out starting with pin planning.

> * Looks like the 6847 footprints could be .1" of so closer together.
> * I assume 0805 footprints to maintain ability to hand solder?

I can hand solder as small as 0402s but the 0805s and 0603s are just
more pleasant to work with.

> In general, it looks like the underside of the PCB is underutilized, even considering what is below the PCB.
> 

That’s intentional, I wanted significant ground plane.  Remember this is a two-layer board, if it were
four layer I’d have packed a lot more on the bottom.

> 
> 
> 
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