Why NAND gates are preferred over NOR gates?

NAND and NOR gates are universal logic gates, which means any Boolean expression can be implemented without using any other gate. Using only NOR gates or only NAND gates all other Boolean expressions can be created unlike other gates. However, NAND gates are more preferred over NOR gates for various reasons. 

• NAND gates are easier to implement than NOR gates. 
• NAND gates can be constructed using fewer transistors than NOR gates, which makes them more efficient and cost-effective. For example, in TTL ICs using multiple-emitter transistors, a NAND gate requires only two transistors, while a NOR gate requires three. Similarly, in CMOS technology, a NAND gate can be built with four transistors, while a NOR gate requires six. 
• NAND gates have better performance than NOR gates in terms of speed and power consumption. 
• NAND gates have lower propagation delay and lower fan-out than NOR gates, which means they can operate faster and drive more loads. 
• NAND gates also have lower power dissipation than NOR gates, which means they consume less energy and generate less heat. 
• NAND gates have more applications than NOR gates in digital circuits. NAND gates can be used to create memory devices, such as flip-flops and latches, as well as logic functions, such as AND, OR, NOT, XOR, and XNOR. NOR gates can also be used to create these functions, but they require more components and connections than NAND gates. 
• NAND gates can be used to detect if a single input to a digital system has gone low, which is useful for alarm circuits. 

In conclusion, NAND gates are preferred over NOR gates because they are simpler, faster, cheaper, and more versatile than NOR gates. They are the building blocks of many digital devices and systems.