A cable is either a thick rope or a bundle of insulated wires through which electricity passes and is often used to connect a piece of equipment to a power source or to another piece of equipment. A bus is a digital pathway that connects devices and resources. A computer has two main types of bus, called system bus and peripheral bus. While a system bus is an internal path between the computer’s Central Processing Unit (CPU) and its memory, it is connected with a bus cable that the user may never see. The peripheral bus connects the computer to a peripheral device, and if the user purchases a peripheral to attach, the connection will be made through a bus cable, either one that is supplied with the peripheral or one that the user must purchase.
The types of devices that might be connected to a computer via a bus cable include printers, scanners, displays, networks, recording systems, and external disks. The peripheral buses through which they’re attached can be parallel buses or serial buses. AT/ISA (Industry Standard Architecture) bus was an early type of parallel bus that was available as early as 1984. It was phased out with the development of PCI (Peripheral Component Interconnect) bus, the most often used Input-Output (I/O) bus. PCI and AGP (Accelerated Graphics Port) are the parallel buses currently in use, and SCSI connectors are a type of bus cable used with parallel buses.
Serial buses are generally connected to peripherals via USB (Universal Serial Bus) or FireWire®. The USB standard was first introduced in 1996, and the fact that Apple® included it on the iMac® in 1998 increased its popularity. USB is a popular bus cable because of its plug-and-play capability, and USB 2.0 is even faster than the initial standard. FireWire® is an Apple® term for IEEE 1394 port, but it is also known as i.LINK® and Lynx. FireWire® 400 was introduced in 1995 and FireWire® 800 in 2002. A FireWire® port is often provided along with USB 2.0 ports and is popular for external hard drives and speakers.