ISA Full Form is Industry Standard Architecture. ISA is a standard computer interconnection system or bus that was developed in 198. It was originally a 8 bit system but later it experienced subsequent development and advancement when in 1984 and in 1988, the system developed as a 16 bit and 32 bit system respectively. It is generally associated with IBM PC/AT motherboard. The programme was developed by a team of experts led by Mark Dean at IBM.
Only 16 MB of the main memory is available for direct access. It allowed bus mastering by connecting the motherboard (which had dedicated IRQs) to the peripheral cards. ISA allows 16 bits to flow at a time, between slot cards and its associated devices, and the motherboard. The two variables (8 & 16 bit) of the bus runs at different speeds. Whereas 8 bit bus runs at 4.77 MHz, 16 bit bus runs at 6 or 8 MHz .
IBM successfully released full circuit schematics and notable specifications for ISA. It was also used in some non-IBM platforms and devices. But, ISA posed various troubles. Users had to configure several parameters when they needed to install a new device. This trouble influenced the introduction of ISA-PnP, an efficient plug-n-play system. PCI is the successor of ISA. But, ISA is still used for specialized and specified industrial purposes.