Definition
A system bus is the communication pathway that ties a processor together with memory and peripherals, carrying the data, addresses, and control signals that let those parts work as one machine. Every controller board, from a desktop motherboard to the small SoC running an ASIC miner, is organised around one or more buses.
The three logical buses
A classic bus is described as three cooperating parts. The data bus carries the actual values being read or written. The address bus selects which memory location or device register the transfer targets, and its width sets how much memory the processor can reach. The control bus carries the timing and command signals, such as read, write, and clock, that keep every component in step. Together they let the CPU place an address, assert a read, and receive data back over a single coordinated path.
Parallel versus serial
Older buses were parallel, moving many bits at once across separate wires. As speeds rose, the timing skew and crosstalk between those wires became the limit, so modern systems increasingly favour high-speed serial buses that send one bit at a time but clock far faster. Internal buses connect the processor to memory, while external or peripheral buses such as PCI Express and the various serial buses extend out to cards and chips. Inside a miner you will find this same idea at small scale: the SoC reaches flash, sensors, and power-management chips through dedicated serial buses rather than one wide parallel highway.
For the device-side serial buses that branch off the main system, see SPI, which carries firmware and sensor traffic on most control boards.
In Simple Terms
A system bus is the communication pathway that ties a processor together with memory and peripherals, carrying the data, addresses, and control signals that let…