Progress on the ALU board

With six copper layers to play with, routing the ALU board has gone from challenging (if not nightmarish) to relatively easy. When routing vertical traces I no longer have to consider how I'm going to get VDD to the various pads, and routing nets to the connectors is mostly a matter of keeping routing lanes free of vias to avoid having to weave around them.

Here's a snapshot:

The six-layer stackup is:

Layer	Color	Usage
1	Red	Top: SMD pads, simple routing
2	Hatched Red	Ground plane — not shown
3	Dotted Green	Unused, probably inter-board nets
14	Light blue	Mostly vertical routing
15	Hatched Blue	VDD (power) plane — not shown
16	Blue	Bottom: Mostly horizontal routing

All of the VDD and GND nets have been routed. Ratsnest shows only 58 airwires remaining, though that will rise when I finish assigning inter-board nets to connector pins.

At this rate I could have both the ALU and ID boards completely laid out in a week or three. That assumes that I decide to keep using FDV301 and BSS83 FETs as high-side push-pull drivers and not switch to DMN26 parts.