Overview
A CPU, RAM, storage, and peripherals are separate physical chips — a bus is the shared electrical
System Interconnects
Every wire diagram of a computer hides the same question: how do the CPU, RAM, and peripherals
I/O & Interrupts
Peripherals are slow compared to a CPU: a disk read can take milliseconds, which is millions of CPU
I2C, SPI & UART
Below the level of PCIe and USB, most chip-to-chip communication on a circuit board — a sensor
USB
USB (Universal Serial Bus) is the dominant peripheral connection standard for everything from mice
Interrupt controllers
The hardware between a device asserting a line and a CPU taking an interrupt: PIC, APIC, MSI, and Arm's GIC.