Hardware components of the PC
Computer Buses
The ISA bus

Industry Standard Architecture (ISA), (pronounced eye-sa) is the name of a very common interface bus design. The ISA bus is a 16-bit wide data bus, allowing the transfer of computer data 16 bits wide to flow between an ISA card and the system bus at a time. The ISA bus system is a standard feature in the vast majority of motherboards.

ISA adapter cards, like all adapter cards, are designed with a unique physical connecting edge that simply push-fits into matching ISA expansion slots on the motherboard of a PC.