Question Regarding IC pin numbering and logic gates

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Discussion Overview

The discussion revolves around the assignment of IC pin numbers to inputs and outputs of logic gates in the context of a homework problem involving integrated circuits. Participants explore the identification of pin configurations and the wiring of logic gates on a breadboard.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • The original poster expresses confusion about how to assign IC pin numbers and the meaning of various labels (A, B, Cin, S, count) in the context of their homework assignment.
  • One participant suggests looking up logic symbol images and determining the pin configurations of specific IC chips that contain the required logic gates.
  • Another participant mentions the existence of logic gate packages, such as the 7400 series, and advises checking data sheets for pin numbers and configurations.
  • There is a note that unused inputs on logic gates should not be left unconnected, and that sometimes the choice of which gate to use within a package can depend on external wiring considerations.
  • The original poster later reports successfully completing the task of building a one-bit full adder, indicating progress in understanding the topic.

Areas of Agreement / Disagreement

Participants generally agree on the need to refer to specific IC data sheets for pin configurations and the importance of understanding the function of each gate. However, there is no consensus on the specific meanings of the labels A, B, Cin, S, and count, as these are context-dependent.

Contextual Notes

The discussion does not resolve the specific meanings of the labels used in the homework problem, and there may be assumptions about prior knowledge of integrated circuits and logic gates that are not explicitly stated.

Who May Find This Useful

Students working on homework related to integrated circuits and logic gates, as well as those seeking clarification on wiring and pin assignments for logic gate configurations.

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Homework Statement


http://i.imgur.com/k8nq4HZ.jpg
So I need to assign IC pin numbers to the input and output of the logic gates.

Homework Equations



None

The Attempt at a Solution



I only have limited knowledge on integrated circuits as a whole, so I'm pretty confused altogether. I know that I can hook up inputs and outputs onto my IC, and then produce a result, but how do I know which pin numbers to use?

Edit: I learned a bit more about integrated circuits and logic gates over the internet, so I understand that each integrated circuit has a built in system of logic gates, and the pins represent either input, output, ground, or voltage source. However, I am still confused about what to do for this, I know that I'll probably be using multiple integrated circuits and using wires to replicate the situation in the picture, but I'm confused about a few things.
On a breadboard, what exactly is A, B, Cin, S, and count?
Also, is this assignment as simple as I think it is? Just wiring together integrated circuits according to the diagram?
 
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Your picture shows a series of logic gates. look up logic symbol images, to see the differences. If you have a specific IC chip in hand that you know has these specific logic gates, then you have to determine which pairs of pins correspond to what types of gates.

While it has been a while since I played with logic chips, the ones I remember were of a type- one chip was all AND gates, another was OR gates, and so on. if this is the case, you will need a set of chips, then get each ones' pin-out configuration, and that will point you toward the wiring of them.

As for the letters; while I do cannot know what specifically they refer to in your situation, by the setup, A and B are choices (maybe switches, push buttons, etc) that determine if Cin reaches count or S is enabled.

Reading the logic shown from left to right and top down should enable you to determine what outcome you get for a given input. for example: If you choose ONLY A or ONLY B or ONLY Cin, you get S. any combination of two or three of the options negates that possibility - that comes from the two XOR (exclusive OR) gates at the top. Similarly you can determine what specific set (or sets) of selections allow for count to occur.

Hope this helps, and does not state what you already know. *grin*
 
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Logic gates are available in many different forms. Have you been told what family of devices to use or what technology?

For decades you could/can buy logic gates in "packages" of 2 to 8 gates all of the same type on one chip. A common family is the 7400 series...

http://en.wikipedia.org/wiki/List_of_7400_series_integrated_circuits

See the table.

For example a 7402 contains four NOR gates, each having two inputs and one output.

If you look at the data sheet for it will give you the pin numbers for the inputs and outputs.

Remember that the inputs of unused (spare) gates should not be left unconnected.

PS: In general it doesn't matter which of the gates within a package you use. However sometimes you choose one instead of another in order to make the external wiring easier/shorter. For example when connecting the output of one gate to the input of another (of the same type) it helps if they are in the same package and/or the pins are adjacent.
 
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Thank you for all your help, combined with my questions to the professor and the knowledge I found on the internet, I successfully completed my task of building a one-bit full adder in the lab. Tons of wires running around everywhere, but I got it done.
Thanks again.
 
Well done. That's quite a complex "first circuit" to build. I think mine was a lot simpler.
 

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