Converting numbers between binary and another base

Abstract

Dedicated convert hardware is disclosed for performing bidirectional conversions of numbers between binary and another base b (illustratively decimal) for use in a data processing system. The dedicated convert hardware comprises a special purpose multiply-and-add unit and a convert register. The output of the multiply-and-add unit is coupled to the input of the convert register, and the output of the convert register is recycled to the inputs of the multiply-and-add unit. The multiply-and-add unit is hardwired to multiply the input by b and concurrently add the value at a separate digit input. Means are also provided for initializing the convert register with zero or with any desired number. The convert hardware is operated to convert a number from radix-b to binary by first initializing the convert register to zero and then iteratively clocking the multiply-and-add unit output into the convert register while presenting to the digit input of the multiply-and-add unit successively high- to low-order digits of the radix-b number. The convert hardware is operated to convert a binary number to radix-b by first initializing the convert register with the fractional part of a product N*b.sup.-m, where N is the binary number and m is an integer greater than zero, and then repetitively clocking the output of the multiply-and-add unit into the convert register while the digit input of the multiply-and-add unit is held at zero. The integer part of each successive multiplication constitutes the successive radix-b digits.