• The pins 2 and 3 of the 7490 serve as a reset for the output. It will reset the output to zero, provided both of them are high or have current running through them. We connected them both to ground thus the output will reset back to zero after it reaches 9.

• If there was current running through both of the pins then the output would be zero.

c. What is the function of pins 6 and 7?

• Pins 6 and 7 of the 7490 function like pins 2 and 3, as a reset for the output, but instead of it being 0 the reset is to 9. The output will reset to nine if there is current running through both pins. We connected pins 6 and 7 to the ground like pins 2 and 3, this would prevent the output from being only nine and let the 7490 continue to count.

d. What happens when any of these pins (6 or 7) are raised to logic "1"?

• The output will reset to 9 if there is current running through both pins.

e. What is the purpose of connecting pin 1 to pin 12?

• We connected pin 1 to pin 12 of the 7490 to determine when the second input would have current running through it. Pin 12 was an output pin and would have current in periodic intervals, thus the second input of the 7490 would be high periodically or only if the output of pin 12 is high.

• The output pins of the 7490 are 8, 9, 11 and 12. We connected them to the input pins 13, 14, 12 and 15 of the 7442 respectively.

Part B - Operating the 7442 BCD-to-decimal decoder.

a. What are the input pins of the 7442?

• The input pins are 13, 14, 12 and 15

b. How did you connect them to the 7490?

• We connected the input pins 12, 13, 14 and 15 of the 7442, to the output pins 11, 8, 9 and 12 of the 7490 respectively. This would determine when or which output pin would be high, and thus which LED would light.

c. Describe the behavior of the LEDs connected to the outputs of the 7442?

• The LED connected to the output pins of the 7442 would light up and turn off depending where or to what output pin they were connected to. The lights could be made to appear as if they were turning on at random. Only one light remained on while the others were turned off. Which LED would light up could be controlled, by fiddling with the input pins of the 7442.

Part C - Operating the 7447 seven-segment decoder.

a. What are the input pins of the 7447?

• The input pins are 1,2,6 and 7

b. How did you connect them to the 7490?

• We connected them to the output pins of the 7490. Pin 1 was connected to output pin 9, pin 2 to output pin 8, pin 6 to output pin 11, and pin 7 to output pin 12.

c. Describe the behavior of the LEDs connected to the outputs of the 7447?

• The LEDs as opposed to those connected to the output pins of the 7442 would light up in such a way that a number was displayed, on the seven segment LED. The number displayed by the lights would in turn be counting up or incrementing, and then reset when it reached 9 or 5 depending whether or not it was wired to do this.

Part D - General Observations.

If you were to describe the experiment to your 12-year old younger brother or sister, or to your mother, how would your description read?

• The 7490 chip counts from 0 to 9, it sends the numbers to the 7442 in the form of electrical impulses where the numbers are represented by a series of 1’s and 0’s. 1 meaning there is current passing through the wires or connections and 0 meaning that there is none. The 7442’s job is to take these messages or packets of electrical signals and determine which LED or light will turn on. The same message or electrical signal is sent to another chip the 7447, which is connected to a seven segment LED. The seven segment LED is similar to the way that the LCD of your calculator, in the sense that they display a number the same way. And given the decoded signal from the 7447 the seven segment LED will show a number and count, pretty much the same way the lights connected to the 7442 turn on.