Why is binary data representation and signaling the preferred method of computer?

Answer 1

The short answer is that it's cheaper. Base 2 (binary) is the most primitive form of numeric notation there is and it is extremely simple to implement using a bewildering array of mediums. For example, a switch is either on or off; a capacitor has a sufficient charge or it does not; polarised particles are either positively or negatively charged; a punch card has a hole at a given position or it does not; a DVD either has a flat or a land; a barcode element either reflects light or it absorbs light; and so on.

While it is certainly possible to implement a digital computer using a numeric base other than base 2, the complexity (and the cost!) of interpreting those bases increases exponentially. Polarised digital states (yes/no, true/false, on/off, black/white, positive/negative) are extremely simple to detect and represent because there are only 2 possible states and 1 threshold per digit. More importantly, switching from any one state to any other state is a constant time operation.

Consider the capacitor: it either has sufficient charge or it does not, but it must be refreshed at regular intervals in order to maintain state (if we don't refresh often enough, a full charge will drain away in just a few milliseconds resulting in a misread digit). But if the specific level of charge actually indicated a digit in the range 0 to 9 we'd not only need much larger capacitors to cover the range with comfortable margins of error between refreshes, we'd also need extremely precise transistors to both read and refresh the charge. The more digits we represent per capacitor, the more complex it becomes.

Answer 2

Computers are designed to work under a binary form because it operates faster than an analog system. It also is a much simpler design verses having three or more levels of varying signals.