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In the "wired AND and OR" gates pictured can anyone explain what the voltage levels will be for each function?

For AND, I see the output is A*B and for OR, A+B. Is this correct? Also, is measurement of voltage within some lower/upper threshold required to determine result of the output?

Finally, I'm confused what law is used to determine whether the two parallel diodes result in an added or multiplied input values. Can anyone provide this?

PS - I'm trying to build more logical functions out of XOR and AND is required. I don't think it's possible (not universal gate) but a suggestion to use wired AND was provided as a solution.

AND:

and

OR:

or

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    \$\begingroup\$ notaorb - Hi, Please remember the site rule which says that when a post includes content (e.g. text, image, photo etc.) copied or adapted from elsewhere, that content must be correctly referenced. For online content, the source webpage or PDF etc. should be linked as a minimum (references for books / articles should include title, author(s), publisher, edition, page numbers etc. - a typical citation). Therefore please can you edit your question to include the original source webpage/PDF links for those images, and remember to include that in future. Thanks. \$\endgroup\$
    – SamGibson ♦
    Commented Sep 19, 2023 at 1:56
  • \$\begingroup\$ Your confusion comes from the usage of the operators. For boolean operations, AND (conjunction) is often shown as the dot, and OR (disjunction) is often shown as the plus. However, this does not mean that voltages are multiplied (with what unit as result?) or added. \$\endgroup\$
    – the busybee
    Commented Sep 19, 2023 at 5:59

2 Answers 2

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For AND: Only if both inputs are high the output is 5V. Otherwise the output is 0.7V.

For OR: Only if both inputs are Low the output is 0V. Otherwise the output is 4.3V.

These gates does not have gain so no threshold can be achieved. Example, if AND gate inputs are A=5V and B=3V the output is 3.7V, i.e. output does not reach 5V rail. The threshold can be achieved with next circuit only (connected to output).

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Your two circuits are identical, but of opposite polarity.

In the AND gate, if either (or both) inputs are Low, the output will be pulled Low. If neither input is Low, the resistor will pull the outpu High.

In the OR gate, if either (or both) inputs are High, the output will be pulled High. If neither input is High, the resistor will pull the output Low.

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