Hardware

In the fetch–decode–execute (FDE) cycle, the program counter holds the next instruction address, the memory address register sends it, memory returns the instruction through the memory data register, and the current instruction register holds it for decoding and execution. The accumulator stores intermediate results.

Higher clock speed, more cores and larger cache can improve performance, but software parallelism, heat and other bottlenecks limit gains. Embedded systems are dedicated computers inside larger devices.

Output devices include displays, projectors, printers, speakers and actuators. A sensor measures a physical quantity such as temperature, pressure, light or moisture; an analogue signal may need analogue-to-digital conversion before processing. Actuators turn digital decisions into physical action.

Magnetic storage offers high capacity at low cost but has moving parts. Optical media are portable and useful for distribution or archive but slower and lower capacity. Solid-state storage has no moving parts, so it is fast, quiet and robust but can cost more per unit and has limited write endurance.

Virtual memory uses secondary storage when RAM is insufficient; it prevents immediate failure but is much slower and can cause thrashing.

MAC addresses are hardware identifiers used locally; IP addresses identify network locations and may be IPv4 or IPv6, static or dynamic. A device can have both. A router commonly assigns private addresses through DHCP and uses network address translation for internet access.