MPX-16 census

I've never heard of anybody making more than double-sided PCBs at home (I would love to be proved wrong!). But just about any PCB manufacturing company could do it. The advantages of more layes are : You can route more tracks in the same area. A trivial example of this is that you can normally only route one track between 2 adjacent IC pins of a DIL pacakge on a particular layer. More layers -> more traces can be fitted in. More importantly you can have particular layes for power and ground planes. That is, one layer will be almost all copper, with 'holes' round pins you don't want to be connected to ground, and connected to those pins you do wany grounded. Doing this will have a much lower impedance (it's the inducatance that really matters, not the resistance, BTW) than normal traces. You can also shield traced inside the board between ground planes. And you can design traces as striplines over the ground plane (and thus know their characteristic impedance) for high frequency work. I doubt any 8088-based design needs you to go that far, but the dedicated power and ground planes would probably be almost essential. At a guess, it was a 6 layer board. Certainly 4 layers (signal traces on the outside, intenral power and ground planes), I think there are hidden signal traces too. -tony