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Saturday, April 20, 2019

Atanua| 74ls85 4-BIT MAGNITUDE COMPARATOR

Today's blog is about the 74ls85 TTL. To build a circuit with this chip you will need two 4 pack dip switches and three led's. A datasheet is below. This TTL will compare the combined value for the 4-bit input of A inputs vs the B 4-bit inputs. The output will send a high to only one of the led's, AB depending on the condition. 



Comparison of words greater than 4-bit can be accomplished by cascading 'ls85 as described in the data sheet. The 74ls85 compares two separate 4-bit words, or numbers, coming from two different sources, such as counter, shift register, etc., including hard-wiring one number on the chip. One 4-bit word is placed on the inputs A0 thru A3, with the Least Significant Bit on A0. The other word is placed on inputs B0 thru B3 A 7 segment display can be implemented in the circuit by joining the inputs to a decoder that leads to the display. This will show numeric values.


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