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I have been learning about digital electronics and playing with some simple integrated circuits like the 7400 series. The 7400 chip, for example, has four NAND gates and I understand some of the uses of this chip. I can see from, for example, Texas Instrument's website that these simple type of chips are still sold.

It seems that most electronics today is very small like laptops and smart phones. So my first question is:

What is the use of simple integrated circuits like the 7400 chip today besides as chips used for learning? Where are they needed?

Where can these chips be found in products that are produced today?

The second question is related (and I don't think it makes sense to start an entirely new question on this, but correct me if I am wrong):

Are basic logic chips, like the 7400, still being produced large scale today?

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  • \$\begingroup\$ LED seven segment displays ARE NOT used in laptops and phones but they are used prolifically in other areas. Voting to close this question as soliciting opinions. \$\endgroup\$
    – Andy aka
    Commented May 19, 2016 at 14:28
  • \$\begingroup\$ A NAND gate is a NAND gate is a NAND gate - the technology changes with time but the principles stay the same. Complex circuits (found in integrated circuits) are made up from lots of simple circuits which are often repeated thousands of times. You learn to handle the complex by starting with the simple. Sometimes you just need a simple circuit such as a few gates to 'glue' the complex circuits together so they can communicate with each other. \$\endgroup\$ Commented May 19, 2016 at 14:38

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For you second question, parts such as TI's 7400 NAND show as still in active production. They wouldn't be being manufactured if people weren't using them in large volumes.

There are many places where they might be used, whenever a circuit designer has a need for them. I know that may seem unsatisfactory, but there are billions of products out there and millions of different designs and applications. It would be pointless to speculate what might have them.

I will leave you with one example that I know of - some vent fans in bathrooms/toilets. This might seem like an odd place for something like that, but in fact they are used to form a simple oscillator circuit with a capacitor feeding the input of a chain of NAND gates. This can then be used for timing of auto-off (ever wondered why the fans stay on for a few minutes after you turn off the switch?).

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I use them when I need to.

Need to gate a digital signal from an external source as well as perhaps perform a level shift in one IC? An AND gate with a logic family like 74HCT will do the job.

Need to control whether a digital signal is original polarity or inverted dynamically? Throw down an XOR gate - again, the potential to level shift is in there for free pretty much.

As Tom Carpenter points out, oscillators are another common use, as well as modulating / demodulating signals for longer distance transmission (IR circuits, even a cheap low-distance alternative to true RS485).

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