1. Introduction Molecules: made up of atoms of individual elements.
Atoms: made up of a nucleus surrounded by orbiting electrons.
Nucleus: made up of protons and neutrons.
Protons: have a positive charge which attract orbiting electrons, which have a negative charge.

2. Introduction
Electric current is when electrons flow from one atom to the next.
Voltage is electrical potential energy.
Ohm’s Law is a fundamental equation in electronics: V = R  I; voltage across a component is equal to the current through it multiplied by its resistance.

3. Atomic Structure
Neutron: particle in nucleus of atom having no charge (neutral).
Electron: negatively charged particle orbiting nucleus of atom.
Orbital path: paths of electrons orbiting atom’s nucleus.
Atomic number: number of protons in nucleus of atom.

4. Introduction
Kirchhoff’s Current Law (KCL): explains why current entering a node must equal current leaving node; current cannot be created or destroyed.
Kirchhoff’s Voltage Law (KVL): voltage supplied from one or more sources must be the same amount as voltage dropped across one or more circuit elements.

5. Kirchhoff’s Voltage and Current Laws
Figure 2.4: Two resistors in series.
Figure 2.9: Two resistors in parallel.

6. Breadboarding
Breadboard: device with hidden interconnections on which to build prototype circuit.
Trace: copper line on circuit board connecting one component to another; path for current to flow on circuit board.

7. Breadboarding
Simulation: entering a schematic (drawing) of a circuit to test into a computer program which calculates voltages and currents throughout the circuit without physically building the circuit.
Prototype: circuit built functionally the same as a circuit to test.

8. Introduction
Digital electronics is based on the combination and switching of logic levels.
Physically, logic levels are represented by voltages.
Logic levels are usually specified as 0 or 1 (bits).
Each logic level corresponds to a digit in the binary (base 2) number system.

9. Introduction Time-varying digital waveforms:
Periodic waveforms: repeat a pattern of logic 1s and 0s.
Aperiodic waveforms: do not repeat.
Pulse waveforms: produce a momentary variation from a constant logic level.

10. Digital Versus Analog Electronics
Analog: physical, continuous quantity; analog voltage or current can have any value within a defined range.
Digital: physical quantity by a series of binary numbers; can have only specific discrete values.

11. Digital Logic Levels
Logic level: voltage level that represents a defined digital state in an electronic circuit.
Logic LOW (logic 0): lower of two voltages in a digital system with two logic levels.
Logic HIGH (logic 1): higher of two voltages in digital system with two logic levels.

12. Binary Inputs
Most significant bit (MSB): leftmost bit in binary number; largest positional multiplier.
Least significant bit (LSB): rightmost bit of binary number; smallest positional multiplier.
Truth table: list of output levels of a circuit corresponding to all different input combinations.

13. Decimal-to-Binary Conversion
Sum of Powers of 2: convert decimal number to binary by adding up powers of 2 by inspection, adding bits to fill up total value of number.
Repeated Division by 2: any decimal number divided by 2 will leave a remainder of 0 or 1.

14. Hexadecimal Numbers
Hexadecimal number system: base-16 number system written with sixteen digits, 0–9, and A–F, with power-of-16 positional multipliers.
Hexadecimal (hex) numbers: primarily used as shorthand form of binary notation.

15. Counting in Hexadecimal
Table 3.4: Hex Digits and Their Binary and Decimal Equivalents.

16. Digital Waveforms
Digital waveform: series of logic 1s and 0s plotted as a function of time.
Timing diagram: digital waveform, typically with multiple signals on one plot.

17. Periodic Waveforms
Periodic waveforms repeat same pattern of HIGHs and LOWs over specified period of time.
Clock: special case of a symetrical, periodic waveform with a specified frequency.
Time LOW (tl): time during one period that waveform is in LOW state.

18. Periodic Waveforms
Time HIGH (th): time during one period that waveform is in HIGH state.
Period (T): time required for periodic waveform to repeat.
Frequency (f): number of times per second that periodic waveform repeats.
Duty cycle (DC): fraction of total period that digital waveform is in HIGH state.

19. Pulse Waveforms
Pulse: variation of voltage from one logic level to opposite level and back again.
Rising edge: part of a pulse where logic level is in transition from LOW to HIGH.
Falling edge (trailing): part of pulse where logic level is in transition from HIGH to LOW.

20. Basic Logic Functions Figure 4.1: Inverter Symbols
Figure 4.2: 2-Input AND Gate Symbol

21. Basic Logic Functions
Figure 4.6: 2-Input OR Gate Symbol
Figure 4.7: OR Function Represented by Switches in Parallel

22. Basic Logic Functions
Active Level: logic level defined as “ON” state for particular circuit input or output (either HIGH or LOW).
Active LOW: active-LOW terminal considered “ON” when in logic LOW state.
Active HIGH: active-HIGH terminal considered “ON” when in logic HIGH state.

23. Derived Logic Functions
Figure 4.12: 2-Input NAND Gate Symbol.

24. Derived Logic Functions
Figure 4.13: 2-Input NOR Gate Symbols.

25. Derived Logic Functions
Figure 4.18: Exclusive OR (XOR) Gate Symbols
Figure 4.19: Exclusive NOR (XNOR) Gate

26. DeMorgan’s Theorems and Gate Equivalence
Figure 4.21: NAND Gate and DeMorgan Equivalent (positive and negative NAND)

27. Logic Switches and LED Indicators
LED (Light-Emitting Diode): electronic device that conducts current in one direction only and illuminates when it is conducting.
Figure 4.31: Light-Emitting Diode (LED)

28. Enable and Inhibit Properties of Logic Gates
Digital Signal (or Pulse Waveform): series of 0s and 1s plotted over time.
Enable: logic gate is enabled if it allows a digital signal to pass from an input to the output in either true or complement form.
Inhibit (or Disable): logic gate is inhibited if it prevents a digital signal from passing from an input to the output.