This brings us along to designs that are rather common even though we don't normally think of them as either common or systems. By this, I refer to SoC's - Systems On A Chip. As the name implies, they are full (or nearly so) computers implemented as single mother-huge silicon chips (relatively speaking). On the die you'll find a CPU or microcontroller, supporting electronics for same, an MMU, and enough interfaces to do whatever you want, be it plug in a USB keyboard and mouse, an Ethernet adapter, or a simple USB-to-serial converter circuit. An excellent example of a SoC is …

So, let's get down to the nitty-gritty.

Let's lay one thing out first: At some point you're going to have to start trusting your toolchain because it simply won't be possible to accomplish some of the necessary tasks yourself. The lowest possible level sseems as good a place as any to start. I mean silicon wafers, the basic component of integrated circuitry. Let's face it, nobody's in a position to turn ordinary sand and handfuls of trace elements into silicon wafers themselves. This is a very complex operation that you can't do in your basement these days. There are lots …