Abstract: An input list of N numbers is clocked through a first sort stage having S1 locations entered into an interstage memory as S2 groups of S1 numbers each. The S1 numbers in each group are in numerical order. The first number in each group forms an initial group of S2 numbers which necessarily includes the smallest number of the N input numbers. This initial group is loaded into a second sort stack having S2 locations which arranges the initial S2 numbers in numerical order. The smallest number forms the first number in the output list. A replacement number from the interstage memory is numerically sorted into the second stack each time the smallest remaining number is clocked out. This replacement number is the next number from the same group as the most recently clocked out number. Each new smallest remaining number must either be the second number in the second stack or the replacement number.

Abstract: An input list of N numbers is clocked through a first sort stack which provides S2 groups of S1 numbers each arranged in ascending numerical order. The numbers are stored in a buffer where the first location within each group always contains the smallest number in that group. These S2 first numbers are loaded into a second sort stack which arranges them in ascending numerical order. The first location in the second stack contains the smallest number in the entire list of N numbers. This smallest number is clocked out of the second stack to form the first number in the output list. A replacement number is numerically sorted into the second stack from the S2 groups each time the smallest remaining number is clocked out. This replacement number is the next smallest number from the same group as the most recently clocked out number. Each time the smallest remaining number is clocked out, the remaining numbers in the second stack are rearranged to accommodate the replacement number for maintaining numerical order.