Bits and Bit Technologies

What is a Bit?

BIT - BInary digiT

A bit is an ‘entity’ having two distinct, distinguishable, discrete states. Generically designated as $\circ$ and $|$.

A bit can be realized by any physical object that has two stable states that can be distinguished confidently.

• Think of a transistor’s on and off state — when passing current, the bit is $|$, when no current, the bit is $\circ$
• Additionally, think of a CAN bus, there is no off or on state, but rather a low and high voltage to differentiate. One line runs usually at 2.5v and the other usually around 5v, differences between both wires can be interpreted as $|$ or $\circ$ because they are predictable and stable.

Semiconductors

Start with silicon,

• MOSFET - Metal-Oxide-Semiconductor Field-Effect Transistor ^e5350b
  • controls the current between the source and the drain using the electric field generated b the gate voltage as the control variable
  • we use the cut-off region ($\circ$) and saturation region ($|$) digitally
  • we don’t use the linear region because it’s not stable, leads to distortion, and can lead to incorrect bits.

Ferromagnetism

• Work by magnetizing a thin film of ferromagnetic material on both sides of a disk
• Sequential changes in the direction of magnetization (at a granularity of millions of magnetic domains, forming a magnetic dipole and generating a magnetic field) represent bits

Byte

One Byte (B) is defined as an aggregation of 8 bits.

Nibble

One Nibble is defined as an aggregation of 4 bits, or $\frac{1}{2}$ of a Byte.