NANDs

NAND gates are a class of digital logic gates in which the output is the negation of the logical AND of the inputs. For a 2-input NAND gate, the output is low only when both inputs are high; otherwise it is high. The truth table is simple: if either input is 0, output is 1; if both inputs are 1, output is 0. NAND gates are functionally complete, meaning any Boolean function can be implemented using only NAND elements. This makes them a common building block in integrated circuits. In practice, 2-input CMOS or TTL NAND gates are widely used, and more complex functions are built by combining multiple NANDs. Simple identities allow implementing AND, OR, and NOT by arranging gates in pairs or with tied inputs. NAND gates are valued for their regular structure, compatibility with standard fabrication processes, and ease of scaling to different fan-in configurations. They are fundamental in the design of CPUs, memory controllers, and digital signal processing circuits.

NAND flash memory is a non-volatile storage technology that uses arrays of memory cells organized in a NAND-style chain to store data as electrical charge. It is named for the arrangement of cells that resembles a NAND gate when viewed at the chip level. NAND flash provides high storage density and relatively low cost per bit, making it common in solid-state drives, USB flash drives, and memory cards. Access is typically page-based, with erasure happening in blocks and programming in pages. Characteristics include limited program/erase cycles and data retention constraints, addressed with wear leveling and error correction codes. NAND comes in several die generations (SLC, MLC, TLC, QLC) that trade endurance for higher capacity. Its evolution continues to emphasize higher densities, improved reliability, and lower power consumption.