Introductory concept Flashcards Preview

Digital Logic > Introductory concept > Flashcards

Flashcards in Introductory concept Deck (52)
Loading flashcards...
1

logic levels

The voltage level used to represent 1s and 0s are called logic levels.

2

Digital Waveform

Series of pulses.

3

Pulse

It consists of leading(rise time: :10% to 90% amplitude) n trailing edge(fall time : 90% to 10% amplitude). Pulse width is between 50%s od both edges. They can be +ve going or -ve going.

4

Duty Cycle

(Pulse width/time period)*100%

5

The clock

in digital systems, each waveform is synchronized with a basic timing waveform CLOCK. Periodic it is.
Its time period is the time for one bit. and doesn't carry information. During one period, information waveform is either high(1) or low(0).

6

Timing diagrams

A graph of digital waveforms to give the time relationship between them.

7

USB

Universal Serial Bus

8

Data Transfer

1. Serial Transfer
2.Parallel Transfer.

9

Serial Transfer

Pro:
Requires only One line.
Con:
Requires time proportional to the data amt.

10

Parallel transfer.

Pro:
requires one time interval only.
Con:
Requires multiple lines.

11

Logic Gate

A circuit which performs specified logic function (and, or).
ALU consists of many such logic gates.

12

Inverter

The logic circuit of not function. inverting the input.

13

Comparator

The comparison function. A logic gate that performs magnitude comparison. a box with 2 input lines (magnitude a and b ) and 3 output lines ( a>b, a

14

Adder

An adder
adds two binary numbers (on inputs A and B with a carry input Cin) and generates a sum and a carry output (Cout).

15

Subtractor. ( logic circuit)

A subtracter requires three inputs: 2 numbers and a borrow input. 2 outputs :difference, borrow output.
(An adder can do this as its special case of addition)

16

Multiplier

multiplied 2 at a time so 2 input, 1 output product(partial). The circuit can consist of adders in conjugation +some stuff.

17

Division, divider.

Division can be performed with a series of subtractions, comparisons, and shifts, and thus it
can also be done using an adder in conjunction with other circuits.
Two inputs.
output: quotient and the remainder.

18

Code conversion function.

conversion between binary and other codes such as the binary coded decimal (BCD) and the Gray code.

19

Code

A code is a set of bits arranged in a unique pattern and used to represent specified information

20

Encoder

one certain type of encoder converts each of the
decimal digits, 0 - 9, to a binary code. A HIGH level on the input ( 10 input lines for 10 chars) produces logic levels that represent the proper binary code on the
output lines.

21

Decoder

example, displays with seven segments( when all segments lit they show 8 ). Input of binary and appropriate output lines are activated and light the proper segments to display the decimal
digit corresponding to the binary code.

22

The Data Selection Function

Consists of Multiplexer (mux) and demultiplexer (demux).Multiplexing and demultiplexing are used when data from several sources are to be
transmitted over one line to a distant location and redistributed to several destinations.

23

Mux n demux

a logic circuit that switches digital data from several input lines onto a single output line in a specified time sequence is mux and demux is its opposite.

24

time-division multiplexing

during the first time interval, input A data go to output D. During the second time interval, input B data go to output E. During the third time interval, input C
data go to output F.
After this, the sequence repeats. Because the time is divided up among several sources and destinations where each has its turn to send and receive data, this process is called time-division multiplexing (TDM)

25

who uses what for memory in a computer?
to retain binary data for a period of time.

Rom n ram n small caches: Semiconductor.
Registers: Semiconductor flip flops.
Hard drives: Optomagnetic disk

26

Flip Flop

Bistable ( two stable states), store one bit. high output means stored 1.

27

Register

Made of multiple flip flops to store multiple bits.
Shift registers: Shift the bits.
that can be parallelly ( ppl sitting in roller coaster) or serially ( ppl entering bus).

28

Counters

Their basic purpose is to count events represented by changing levels or pulses. To count, the counter must “remember” the present number, hence storage req and flip flops used.

29

A process control system.

Recall the system for bottling vitamin tablets.

30

What is a programable logic device?

A programable logic device has an undefined function at the time of manufacture.