COA Tutorial

Computer Organization and Architecture Tutorial Basic Terminologies Related to COA Digital Number System Computer Organization and Architecture Data Formats Fixed and Floating-Point Number IEEE Standard 754 Floating Point Numbers Control Unit Organization Data Path, ALU and Control Unit Micro-Operations CPU Registers Addressing Modes COA: Interrupt and its types Instruction Cycle: Computer Organization and Architecture Instruction Pipelining and Pipeline Hazards Pipelining: Computer Organization and Architecture Machine Instructions 8085 instructions set 8085 Pin Configuration Addressing mode in 8085 microprocessor Advantages and Disadvantages of Flash Memory BCD to 7 Segment Decoder Biconnectivity in a Graph Bipartite Graph CarryLook Ahead Adder Control Signals in 8155 Microprocessor Convert a number from base 2 to base 6 Ethernet Frame Format Local Broadcast Address and loopback address Microprocessor classification Use Case Diagram for the online bank system 8086 Microprocessor Pin Configurations 8255 Microprocessor Operating Modes Flag Register of 8086 Microprocessor Data Transfer and Manipulation 8085 Arithmetic Instructions Assembly Language Register What is Cache Associativity? Auxiliary Memory in COA Associative Memory in Computer Architecture SCSI Bus in Computer Architecture What are Registers in Microprocessor What is Associative Memory 1 Persistent CSMA What is Floating-Point Representation in Computer Architecture? What is a Serial Port in a Computer? What is Cluster Computing What is Batch Processing in Computer Advantages of Client Server Architecture Spooling Meaning in Computer System Magnetic Core Memory Magnetic Ink Card Reader Decision Making Tools and Techniques Digital Electronics using Semiconductor Memory What is Internal Chip Organization in Computer Architecture? What is Hardwired Control Unit? Definition of Diodes in Electronics Advantages of FSK Web Server Architecture How the OS interfaces between the user, apps, hardware? Discuss the I/O Interface in Computer Architecture Difference between Internal Fragmentation and External Fragmentation MDR in Computer Architecture

BCD to 7 Segment Decoder

What is BCD?

BCD is called Binary Coded Decimal. As you know there are a lot of forms in which we can represent the number like Binary, decimal, hexadecimal, and octal etc.

In Binary format, we can represent any number with the help of just two numbers which are 0 and 1. It is also called base 2 format.

For example, to represent 12 in Binary we will write 1100, and to write 13 we will write 1101.

In decimal format we can represent any number with the help of 10 digits (0 to 9) and it is called the base 10 format. In the real world, we use the decimal format to represent any number, while the Binary number format is used by computers and electronic devices.

In BCD, we can represent the Binary equivalent of each digit of the decimal digit (0 to 9). To represent maximum value 9 we need 4 bits of Binary, so in BCD we used 4 digits to represent the equivalent decimal number.

Suppose four digits are A, B, C, and D where A is MSB (Most Significant Bit), and D is LSB (Least Significant Bit). Let’s see the BCD equivalent of each decimal digit:

Decimal DigitABCD
00000
10001
20010
30011
40100
50101
60110
70111
81000
91001

Seven segment display

Seven segment is a special kind of electronics circuit that uses 7 LEDs to represent the digits from 0 to 9. As we know, Binary 1 means logic high or ON and Binary 0 means logic low or OFF. This same phenomena applies on 7 segment displays where different combinations of these 7 LEDs ON and OFF make the decimal number.

BCD to 7 Segment Decoder

From the above image we can see the arrangement of 7 LEDs represented as a,b,c,d,e,f, and g.

These LEDs work in two modes:

1. Common Cathode Mode: In this mode, the cathode of all 7 LEDs is connected together and to blink any led, we have to set logic ‘1’ to its input pin.

2. Common Anode Mode: In this mode, the anode of all 7 LEDs is connected together and to blink any led, we will have to set logic ‘0’ to its input pin.

Generally, we use common cathode mode.

For making 0:
We will set the led a,b,c,d,e,f at logic ‘1’ and led g at logic ‘0’.

For making 1:
We will set led b,c at logic ‘1’ and the rest LEDs at logic ‘0’.

For making 2:
We will set led a,b,g,e,d at logic ‘1’ and res LEDs to logic ‘0’.

For making 3:
We will set led a,b,c,d,g at logic ‘1’ and led e,f, at logic ‘0’.

For making 4:
We will set led b,c,f,g at logic ‘1’ and rest led at logic ‘0’.

For making 5:
We will set led a,c,d,f,g at logic ‘1’ and rest led at logic ‘0’.

For making 6:
We will set led a,c,d,e,f,g at logic ‘1’ and rest led at logic ‘0’.

For making 7:
We will set led a,b, and c at logic ‘1’ and the rest led at logic ‘0’.

For making 8:
We will set led a,b,c,d,e,g at logic ‘1’ and rest led at logic ‘0’.

For making 9:
We will set led a,b,c,d,f,g at logic ‘1’ and rest led at logic ‘0’.

Decoder: decoder is an electronic circuit that can change one form into another form.
The decoder has some input pins and some output pins to get the desired output.

BCD to 7 segment decoder has 4 input pins to take input as BCD number and generate the output as 7 segment value which has 7 digits, so it has 7 output pins.

Using k Map will get the equivalent simplified combination of BCD digits to decide when each digit of LED is going to be set.

To set a:        A + C + BD + BD

To set b:        B + CD + CD

To set c:        B + C + D

To set d:        A + BD + BC + CD + BCD

To set e:        BD + CD

To set f:        A + BC + BD + CD

To set g:         A + BC + BC + CD

The 7-segment display and the decoder are generally used in calculators or in some digital watches.