TEJ2O – Grade 10 Computer Engineering – Computer Electronics Notes

Computer electronics notes What is an Integrated Circuit?

• Integrated Circuit (Chip): small plastic or ceramic package for electric conductors
o 2 to a few hundred connections from the outside
o 1000s of types of integrated circuits
o Gate Identification Number: identifies what type of gate this chip is, along with an

indentation to know what orientation it should be.
o Pins: connects the chip to the breadboard holes from which information is passed o Bus (in hardware): moves data from one place to another
o Bus (chip level): a set of pins that perform a common task

§ Labelled alphabetically (Bus A, Bus B, Bus C…)
• Gates: a barrier or switch that controls how electricity should flow through the computer

o AND, OR, NOT, NAND, EOR/XOR

What is Illustrating Flow of electricity?

  • Illustration Methods: shows how low voltage flows through gates and chips

    o Diagrammatic Repre.: schematic drawings o Numeric Repre.: Truth Table
    o Symbolic Repre.: Boolean Algebra

  • Gate Schematic: pictorial representation of a gate, consisting of letters, lines and figures to illustrate the flow of electricity in and out of the gate.

    o Looks like an elongated “D” shape
    o A and B lines represent input of electricity
    o Y line represents output
    o Actual flow of electricity carried out by several transistors inside the gate

  • Chip Schematic: pictorial representation of the organization of a number of gates into a single chip

    o Numbered rectangles on the side of the diagram represent the pins o VCC pin must be connected to a low voltage power source
    o GND pin must be connected to ground

  • Truth Tables: numerical representation of the inputs into a gate, and the outputs from a gate, recorded in binary in a column format.

    o First Column: input (A)
    o Second Column: input (B)
    o Third Column: output (Y)
    o AandBflowsinatthesametime
    o Records all the possible inputs and outputs of the circuit

  • Boolean Algebra (Boolean Equations): provides a very precise way of illustrating the logic of computer chips.

    o George Boole developed this new way of using algebra to represent logic flows of electricity

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o Eg: Y=A*B What are Gates and Chip?

AND Gate

o
o Elongated capital D shape

o A and B on left represent input
o Y represents output
o Each input can be 1 (on) or 0 (off) o Equation: y = AŸB

Truth Table

o YisononlywhenAandBareon. o 74LS08 (AND) Chip

§ Quad two-input AND gate chip
§ Chip has 14 Pins, connected directly to the inner circuitry
§ Pin 7 is a grounding (GND) pin, pin 14 is has positive +5 volts of

A

B

Y

0

0

0

0

1

0

1

0

0

1

1

1

power

Gate Number (AND) gate

Input Pins

Output Pins

Other Pins

1

1,2

3

7 Ground

2

4,5

6

14 +5 Volts

3

9,10

8

4

12,13

11

• OR Gate
o elongated D with curved back and pointed tip

o
o equation:Y=A+B

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o “+” means OR, not add

o IfeitherAorBareon,Ywillalsobeon o 74LS32 Chip

§
§ Gate number and IO pins same as AND chip (74LS08)

• NOT Gate o

o NOT gate looks like a sideways triangle with a circle on the tip o NOT gate only has 1 input (A)

o Equation: Y =
o Y will always be the opposite of A
o Inverter: when the output is opposite of the input
o The line above A indicates that the signal is switched

What are laws in Boolean Algebra? What is emulation?
What is Negated AND?

A

B

Y

0

0

0

0

1

1

1

0

1

1

1

1

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