I fully appreciate the benefit of power and ground plane usage. All my commercial wire-wrap boards, both those that I've bought and those that I've sold have had 'em. I've used boards with and without low-impedance power and ground planes. I know what the differences are.

However, before there were affordable multilayer boards, people built very good circuit boards with two layers. Even ECL circuits operating at >200 MHz were built using that technology.

Migrating from two-layer to multilayer technology is not trivial. Yes, it's easy to design circuits with power on the top and gnd on the bottom, or vice versa, with signal layers in the middle. That doesn't always lead to the best circuits, though.

Expecting Mike, who's never designed a board before, to design a proper 4-layer board is a long reach, if you ask me. He's limited by not just budget but by knowledge as well.

As for reliability, wire-wrap and stitch-weld were both found to be more reliable than PCB's back in the early days of the space program. Some of those non-PCB circuits are still working just fine out there in space, where nobody can easily get there to troubleshoot and fix 'em.

Wire-wrap allows for higher density than two-layer boards, with shorter signal paths than 4-layer PCB's would allow. That results in better signal quality and reduced HF power-gnd noise. The fact that wires intersect randomly has an averaging effect on crosstalk, which is minimized. Lots of mistakes, e.g. bundling of wires, use of pre-cut wires, etc, have often given wire-wrap a bad reputation. It's possible to screw up nearly anything, and it's been proven again and again.

A basic 8031 circuit, with address latches and data buffers plus EEPROM and RAM would take a board of about 3x4 inches (the max that bEagle can handle. It would autoroute that in two layers in about 15 seconds, and pretty well. Given many hours, it would still not do any better on a 4-layer board. A perfectly functional two-layer board would cost about $2 here where boards are overpriced as can be, and about $0.20 in China. A useable 4-layer board would take much longer to design, because of the quirks of PCB packages' poured ground and power plane requirements, and might or might not work out properly. Often they leave islands of unconnected pour, just because of the inexperience of the board designer. I dont think it's reasonable to expect a complete neohpyte to "whip-up" a 4-layer board when he's not even ready to design a complete circuit yet.

Most of the original 805x boards I bought back in the '70's and '80's worked just fine, despite the fact they were 2-layer boards. Of those, most are still in service, running machines and doing what they were intended to do.

Yes, multilayer boards make high-frequency work easier, as they allow the precise control of signal path lengths to within a millimeter or so. That's not often necessary with circuits that operate at <50 MHz, though.

RE