An iterative method for improving decimal calculations on computers Jose-Luis Sanchez * , Higinio Mora, Jeronimo Mora, Fco. Javier Ferrandez, Antonio Jimeno Department of Computing Technology, University of Alicante, Spain Abstract Since radix-10 arithmetic has been gaining renewed importance over the last few years, high performance decimal systems and techniques are highly demanded. In this paper, a modification of the CORDIC method for decimal arithmetic is pro- posed so as to improve calculations. The algorithm works with BCD operands and no conversion to binary is needed. A significant reduction in the number of iter- ations in comparison to the original decimal CORDIC method is achieved. The experiments showing the advantages of the new method are described. Also, the results with regard to delay obtained by means of an FPGA implementation of the method are shown. Key words: Decimal arithmetic, CORDIC, hardware design 1 Introduction In the past, and among several cultures, different number representation sys- tems were adopted [1]. Nowadays, numbers are commonly expressed by hu- man beings using decimal representation; as a consequence, in the early days of computing, most of the first computers worked with decimal operands [2]. Due to the greater simplicity of binary arithmetic unit and the compactness of binary numbers, decimal arithmetic fell into disuse and for many years it has been difficult to find new proposals of radix 10-based computers. This fact has finally led to a preponderance of binary systems over decimal ones. In spite of * Corresponding author. Email addresses: sanchez@dtic.ua.es (Jose-Luis Sanchez), hmora@dtic.ua.es (Higinio Mora), jeronimo@dtic.ua.es (Jeronimo Mora), fjferran@dtic.ua.es (Fco. Javier Ferrandez), jimeno@dtic.ua.es (Antonio Jimeno). Preprint submitted to Elsevier 27 October 2008