The NexStar User's Guide II - Excerpt from Chapter 10
As discussed in Chapter 3, Celestron's computerized telescopes utilize multiple processors (computers) to provide the complex control necessary for their seemingly effortless GoTo and tracking performance. Inside the mount there are two processors: one for each axis. The processors in the mount are responsible for controlling the rate of motion for each motor as well as executing backlash compensation and a few other movement related functions. As such, these are commonly referred to as the "motor control" or MC. The hand control, commonly referred to as the HC, houses a single processor. The processor in the hand control is responsible for GoTo and calculating tracking rates for each axis, storing and accessing the objects database, the user interface that we deal with to run the scope, and various other tasks. Additionally, there is a processor inside the StarSense camera.
Each of these processors requires a series of instructions commonly referred to as a program, application or code. For general purpose computers, such programs are typically called "software" but for special purpose computers such as these, the common name is "firmware". This firmware must be stored where the processor can access it when the telescope is powered up: special memory in the HC, MC or camera. Since the HC, MC and camera do not have the power or user interface to allow direct download from some outside source, special tools are needed to load firmware into them when the need arises. These update tools are programs which run on a standard desktop or laptop computer. We will discuss their operation in this chapter.