I don't know what this electronic circuit does

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jacklll
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Member advised to use the formatting template for all homework help requests
I have a homework question that asks me to draw up a truth table for the attached circuit.

As you can see I did this (I think correctly). There is also an attached question asking what function the circuit serves - I am not sure what function this is

Half-subtractor circuit schematic with inputs X and Y, an XOR gate output D, and an inverter on Y feeding an AND gate output Bout, above a truth table with columns X, Y, Sum D and Carry B.
Any pointers appreciated.
 
Attachments
  • Half-subtractor circuit schematic with inputs X and Y feeding an XOR gate output D and an inverter-plus-AND gate output Bout, above a truth table of X, Y, Sum D and Carry B.
    6oummfx.png
    21.3 KB · Views: 547
  • Half-subtractor circuit schematic with inputs X and Y, an XOR gate output D, and an inverter on Y feeding an AND gate output Bout, above a truth table with columns X, Y, Sum D and Carry B.
    MOS0tys.png
    14.5 KB · Views: 968
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Discussion

Hi jackill. :welcome:

Why did you call one output "sum" and the other "carry"?
 
Along the same lines as NascentOxygen's post, What do you think "D" and "B" could stand for?
 
Oops - I originally thought this was a half adder but later figured that wasn't correct. I forgot to change the boxes before I uploaded the image.
 
LOL, I tried to cheat and use Google Images to match on the circuit posted. This was the return... o0)

About 3 results (0.77 seconds)
Screenshot of a Google Images search page with a small thumbnail of a circuit schematic and a result count line reading About 3 results.

Image size:
800 × 450
No other sizes of this image found.
Best guess for this image: screenshot
 
Attachments
  • Screenshot of a Google Images search page with a small thumbnail of a circuit schematic and a result count line reading About 3 results.
    ZUVi5E4U8u-u8g5wYGRJocjPniOdvmL6vf09akCcrpxbS3RLdLh6Fo_E18pp093CHxmy=s151.jpg
    1.7 KB · Views: 840
jacklll said:
Oops - I originally thought this was a half adder but later figured that wasn't correct. I forgot to change the boxes before I uploaded the image.

I guess there is a difference between what this circuit does, and what you thought the circuit did.
 
berkeman said:
LOL, I tried to cheat and use Google Images to match on the circuit posted. This was the return... o0)

About 3 results (0.77 seconds)
View attachment 225514
Image size:
800 × 450
No other sizes of this image found.
Best guess for this image: screenshot
Narrow down the image to just the circuit:
Logic circuit schematic with inputs X and Y feeding an XOR gate with output D, and a NAND gate combining X and Y with an inverted input to produce output Bout.

Then search again :wink:
 
Attachments
  • Logic circuit schematic with inputs X and Y feeding an XOR gate with output D, and a NAND gate combining X and Y with an inverted input to produce output Bout.
    Circuit.JPG
    2.1 KB · Views: 529
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jacklll said:
Oops - I originally thought this was a half adder but later figured that wasn't correct. I forgot to change the boxes before I uploaded the image.
Hint: You weren't too far out of the ball park.
 
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Likes   Reactions: berkeman
Reference table of digital logic gate symbols listing AND, OR, NOT, NAND, NOR and XOR, each with its symbol, Boolean notation and truth table.


what your not seeing is an exclusive xnor gate
 
Attachments
  • Reference table of digital logic gate symbols listing AND, OR, NOT, NAND, NOR and XOR, each with its symbol, Boolean notation and truth table.
    a172a616d71c340624f7515b8b4e6d3a.jpg
    32.6 KB · Views: 521
  • Like
Likes   Reactions: berkeman
OK guys, the deadline is up and I couldn't figure it out using your hints :(

Really appreciate the efforts though and I will format my question better next time as per the forum rules.
 
jacklll said:
OK guys, the deadline is up and I couldn't figure it out using your hints :(
See the hint in post #7 above. :smile:
 
jacklll said:
OK guys, the deadline is up and I couldn't figure it out using your hints.

My previous post contained an (intended) obscure hint:

George Jones said:
there is a difference

I figured it out form your truth table, and from

Janus said:
Along the same lines as NascentOxygen's post, What do you think "D" and "B" could stand for?
 

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