In Figure E6-3, which is the schematic symbol for a NAND gate?

A NAND gate is an AND gate followed by a NOT gate (inverter). Its schematic symbol looks like the standard D-shaped AND gate, but with a small circle (the inversion bubble) at its output. In Figure E6-3, symbol 2 represents this D-shaped body with a circle at the output, making it the NAND gate. Symbol 1 is a standard AND gate without the circle. Remembering that 'NAND' stands for 'NOT AND' helps to visually piece together the symbol: the D-shape represents AND, and the bubble represents NOT.