Define ISA

In the context of plug and play, ISA is the Industry Standard Architecture bus. It is the 8-bit/16-bit expansion bus introduced in the IBM PC/XT/AT, running at about 8 MHz, to which add-on cards (sound card, modem, network card) are connected. Resources such as IRQ lines, DMA channels and I/O addresses of ISA cards were traditionally set by jumpers, which led to conflicts; the PnP ISA specification added automatic configuration to this bus.

(In a general architecture context ISA also means Instruction Set Architecture, the set of instructions, registers and addressing modes visible to the programmer.)