There are normally two schools of thought on design for software. Top-down design focuses on the user interaction side of things, determines what those user interactions should be, and works from that point down into the detailed design. Bottom-up design works in the opposite direction, focusing on the functionality that is needed, and working up to the user interface.
There is a third kind of design philosophy, where you have one set of people designing from the top down, and a different group going from the bottom up, and where the two pieces kind of meet in the middle, you spend time figuring out how to make them match. This usually works if both sides have the same vision of what the thing is supposed to do, and you allow plenty of time (and some skilled programmers) to design the "sandwich" layers.
It's further complicated by the fact that the user interface isn't the only controlling input. There are other independent devices that provide input that directly affects the operation of the system. And the hardware has some severe limitations-- for instance, the main user graphic is a visual screen which represents a 3-D perspective "wireframe" view which is supposed to be updated in realtime-- and they didn't bother putting a graphics coprocessor on the board. So they are using the main processor to handle the realtime processing of the 3D view, as well as handling all the rest of the application software.
The best part of this is that the processor was originally chosen partly because it has a "graphics coprocessor" built in, but the folks that actually specified the processor semed to miss the fact that it was designed for a 1/4VGA screen.
And this is their second from-scratch hardware design for the same product.
So really there are four separate directions that are all being designed, trying to lead into one cohesive whole. It's not so much a process as it is an oozing together.
And speaking of oozing...
It looks like I may indeed have some sort of flu or other intestinal upset. Not a happy camper, I. No bike tonight, and most likely crawling into bed at an early hour. Hopefuly not a lot of crawling out of bed as well.
I did manage to find an art supply store (Dick Blick) down here too. Maybe this weekend I can get some things to keep me a little more devoted to my craft.