Electrotechnics digital circuit self study notes 1.24

1.24

Chapter 20 Gate circuits and combinational logic circuits

Four number systems are most commonly used in digital circuits , Every number system has cardinality and bit weight .

1. Decimal system ：0-9, base （ base number ） by 10.
2. Binary system ：0、1, The base number is 2.
3. octal ：0-7, The base number is 8.
4. Hexadecimal ：0-9,A-F, The base number is 16.

Number conversion ：

1. Ten - Two ： Integral part ： except 2 Surplus method , The fractional part ： ride 2 Rounding .

2. Ten - 8、 ... and ： First convert to binary number , Every time 3 The bits are grouped , If the front is not enough 0.

3. Ten - sixteen ： First convert to binary number , Every time 4 The bits are grouped , If the front is not enough 0.

Arithmetic binary operation ： Add, subtract, multiply ; carry , Borrow position .

Pulse signal ： In digital circuits , The signal （ Voltage and current ） It's pulsed （ Jump signal , The duration is short ）.
Parameters ： Pulse amplitude （ Maximum ）、 Pulse rise / Descent time （ From amplitude 10%-90%/90%-10% Time required ）、 Pulse width （ Rising edge 50%- Falling edge 50% Time required , Also called pulse duration ）、 Pulse period （ On - On / Next - Under the 10%-10%）、 Pulse frequency （1/T）.
In digital circuits , It is usually based on the presence or absence of pulse signals , Number , Width and frequency to work , Therefore, it has strong anti-interference ability （ Interference generally only affects the amplitude ）.
Positive pulse 、 Negative pulse , Compare the post jump and initial values .

Expand knowledge

1. base ： The number of digits used in the number system . for example , The cardinality of binary is 2; The base of the decimal system is 10.
2. Position right ： On a certain position in the number system 1 The size of the value represented （ Value of location ）.