Industry Standard Architecture – a bus standard for PCs introduced in 1984 that extended the XT bus architecture to 16 bits. It is designed to connect peripheral cards to the motherboard. It is also referred to as the AT bus.
A common bus architecture on the motherboard of older personal computers. Newer computers generally use the PCI (Peripheral Component Interconnect) bus instead. Opto 22 adapter cards are available for both ISA and PCI bus connections.