Nuts & Volts - February 2004

Personal Robotics

even BASIC Stamp user, the different communications methods, combined with its full set of hardware features offered on the IsoPod make it the ideal universal peripheral. You could easily use it as an R/C servo engine, quadrature reader, sensor reader, and spoon-feed the data to and from your microcontroller or microcomputer of choice. There are many users who have gone this route, then find themselves handing more and more processing power to the IsoPod.

The IsoMax programming language supplied with the IsoPod is really quite unique as well. IsoMax is actually a superset of FORTH, an arcane and venerable language often associated with users who have almost a religious reverence for it. While covering FORTH is beyond the scope of this article, IsoMax incorporates enough sufficiently novel concepts that it is worth mentioning.

The lack of FORTH's popularity,

in my opinion, is that it is really a language construction set. When you define a function, you actually end up factoring it into common elements, and re-using them over and over again. In doing this, you are writing what I call MYFORTH, and every-body's MYFORTH is different. Back when everyone was trying to classify and sort the different languages out there, FORTH was left looking a bit chaotic. This has lead to finding documentation difficult. You will not drive to your local mall, grab a coffee, and decide which FORTH text you are going to buy. Fortunately, there is enough documentation on New Micros' website to get you going.

To begin, the most novel thing about IsoMax is the fact that it actually lives in the IsoPod itself. All you need is a serial port, terminal software, and a power supply. I often start a project by simulating the hardware on my desktop, and getting the bulk

of my program code going before it even sees the real hardware it will be working with.

The other truly unique thing about IsoMax is that it is multitasking, and even the multitasker is implemented in a unique way. The multitasker is actually time-synchronous. What this means is that you establish a frequency at which all of your processes — called virtual machines — get run, and the multitasker runs them one by one, in the order you want them to be run. In essence, you break the flow of time into granules. In every granule of time, everything gets done.

Another neat thing about the multitasker is that while your programs are running, you can actually still communicate with the processor during the foreground task slice. You can set or read registers, change the contents of variables, even write new words that get compiled.