Parallel computing, increasingly used for computationally intensive problems, requires considerable expertise and time, limiting then widespread use. This article presents a data-parallel programming tool to simplify the task of developing parallel programs based on data-parallel type. It has been originally developed for the Hellos operating system running on a network of Transputers, and then ported to the IBM SP/2 system executing two parallel programming environments. With its interface to the C language, it is portable to the parallel environments having the support for the basic message passing primitives send and receive. The use of the tool is illustrated and explained through the example of finding column-sums of a matrix. Finally, the performance of the tool is discussed focusing on the speed-up curves of the parallel programs developed with the tool to solve a numerical and an image processing problem.