Every detail is covered: from power to memory, from the CPU to working with USB. You’ll find all the details about working with both wired and wireless Ethernet, SD cards, and the UART interface. The GPIO chapter is invaluable, covering power budgeting, access, and even small but important details like the correct usage of sudo when working with GPIO pins. You’ll also find details about the 1-Wire driver, the I2C bus. and the SPI bus. If you need to know anything about your Raspberry Pi’s hardware, you will find it here, in Raspberry Pi Hardware Reference.