Gate array is an approach to fast design and manufacture of integrated circuits. A gate array circuit, also known as an Uncommitted Logic Array (ULA) is a prefabricated circuit with no particular function in which transistors, standard logic gates, and other active devices are placed at regular predefined positions and manufactured on a wafer, usually called master slice. Creation of a circuit with a specified function is accomplished by adding metal interconnects to the chips on the master slice late in the manufacturing process, allowing the function of the chip to be customised as desired.
Gate array master slices may be prefabricated and stockpiled in large quanitities regardless of customer orders. The fabrication according to customer specifications may be finished in a fraction of time compared with the fully custom design. The gate array approach avoids having to assemble the required logic from large numbers of discrete components which might otherwise be the only other cost effective solution for small runs and prototypes
This design style is the easiest for design and fastest for processing of the order. Due to mass production of the gate array circuit's, it is also considerably cheaper than having a purpose-designed chip fabricated. Drawbacks are low density and performance. However this style is a viable approach for small-batch orders, as well as for prototyping.
An evolution of this approach is field-programmable gate arrays.