Decoders are combinational circuits that convert binary data into 2N output lines. The binary data is sent via N input lines. On the output lines, the binary data is encoded in a 2N-bit code.
2 to 4 line decoder:
Three inputs (A0, A1, and E) and four outputs make up the two to four line decoder (Y0, Y1, Y2, and Y3). When the enable ‘E’ is set to 1, one of these four outputs will be 1 for each combination of inputs. The block diagram and truth table for the 2 to 4 line decoder are presents below.
Block Diagram
Truth table
The Boolean functions for each output from the Truth table can written as follows:
The terms Y0, Y0, Y2, and Y3 are logically express as follows:
Y3=E.A1.A0
Y2=E.A1.A0′
Y1=E.A1′.A0
Y0=E.A1′.A0′
Circuit Diagram
The following is the logical circuit for the above expressions:
3 to 8 line Decoder
Binary to Octal Decoder is another name for the 3 to 8 line decoder. A 3 to 8 line decoder has eight outputs, including Y0, Y1, Y2, Y3, Y4, Y5, Y6, and Y7, as well as three outputs, A0, A1, and A2. In this circuit, the enable input ‘E’ is utilize. When enable ‘E’ is set to 1, one of these four outputs will be 1, just like a two-to-four-line decoder. The block diagram and truth table for the 2 to 4 line decoder are presented below.
Block Diagram
Truth Table
A logical formulation for the terms D0, D1, D2, D3, D4, D5, D6, and D7 is as follows:
D0=A0′.A1′.A2′
D1=A0.A1′.A2′
D2=A0′.A1.A2′
D3=A0.A1.A2′
D4=A0′.A1′.A2
D5=A0.A1′.A2
D6=A0′.A1.A2
D7=A0.A1.A2
Circuit Diagram
The following is a logical circuit:
Application
- It use in the conversion of codes. This is analogue to digital conversion in the analogue decoder.
- It can also used to distribute data.
- In a high-performance memory system, this decode can utilized to lessen the burden of system decoding.
- As address decoders, the decoders are used in CPU memory location identification.
- It can also used to transform instructions into CPU control signals in electrical circuits.
- They’re mostly employed in data transport and logical circuits.
- They can also use to make simple digital logics such as half adders and full adders, as well as other digital designs.
- The microprocessor selects several I/O devices.
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