The AS17xx is Astec's proprietary semicustom bipolar array. This semicustom IC is a collection of individual transistors and resistors in a fixed configuration. The custom circuit is manufactured by creating a single metal mask to connect the components. This allows the designer to deal with only one mask for the IC layout instead of the actual 10 mask process. The semicustom array is useful for a wide range of functions, both analog and digital. In its simplest configuration, the AS17xx has 76 active devices available, but can be expanded to give up to four times this number in its largest configuration. This expandability of the array is a unique feature, allowing a whole range of semicustom circuits to be manufactured.