*Notes to a video lecture on http://www.unizor.com*

__Electronic Logic__

Let's analyze how diodes can be used to implement operations of mathematical (and computer) logic.

These are operations on variables that can have only two possible values - TRUE (in many cases represented by number 1) and FALSE (represented by 0).

*TRUE and FALSE in Electronics*

First of all, we have to agree on what represents logical TRUE and FALSE or 1 and 0 in electrical circuits.

The standard is that TRUE or 1 is represented by some positive potential on a wire relative to ground, while FALSE or 0 is represented by zero potential relative to ground.

Consider the following circuit

According to our rules about what represents logical TRUE (1) and FALSE (0), the logical value at point

*is FALSE (0) and at point*

**A***it is TRUE (1).*

**B***Binary logical operations*

Disjunction

**OR**(sometimes represented by symbol of addition

**+**or vertical bar

**|**).

The rules are:

**0|0=0, 0|1=1, 1|0=1, 1|1=1**Conjunction

**AND**(might be represented by symbol of multiplication

**·**or ampersand

**&**),

The rules are:

**0&0=0, 0&1=0, 1&0=0, 1&1=1**Exclusive disjunction

**XOR**(might be represented by symbol

**⊕**).

The rules are:

**0****⊕**

*0=0, 0*⊕*1=1, 1*⊕*0=1, 1*⊕*1=0**Unary logical operation*

Negation

**NOT**(sometimes represented by exclamation sign

**!**or symbol

**¬**).

The rules are:

**¬0=1, ¬1=0***Implementation*

Implementation of binary logical operations in electronics involves developing a schema with two input contacts,

*and*

**A***, and one output contact*

**B***. On two input contacts there might be four different combinations of electric potential:*

**C**

**A=0, B=0**

**A=0, B=1**

**A=1, B=0**

**A=1, B=1**For each of these combinations the value of electric potential at output point

*should correspond to the rules of the corresponding binary logical operation implemented in this schema.*

**C**Implementation of unary logical operations in electronics involves developing a schema with one input contacts

*and one output contact*

**A***. On input contact*

**B***there might be two different electric potentials:*

**A**

**A=0**

**A=1**For each of these combinations the value of electric potential at output point

*should correspond to the rules of the corresponding unary logical operation implemented in this schema.*

**B**Examples of implementation of certain logical operations in electronics are presented in subsequent lectures.

## No comments:

Post a Comment