Industry Standard Architecture (ISA) is a bus standard for IBM compatibles that extends the XT bus architecture to 16 bits. It is designed to connect peripheral cards to the motherboard. The protocols also allows for bus mastering although only the first 16 MB of main memory is available for direct access. In reference to the XT bus architecture it is sometimes referred to as "AT bus architecture".
- Extended Industry Standard Architecture (which is a compatible extension)
- Micro Channel Architecture (which was IBM's failed attempt at introducing an incompatible but improved bus)
- Peripheral Component Interconnect (a popular incompatible improved bus)
- XT bus architecture (the predecessor)