This paper presents an architecture for running interactive ray tracing applications on portable devices such as cell phones, PDAs, and head mounted displays and discusses the main issues related to the mapping of this graphics algorithm using fixed-point arithmetic. The paper shows that a floating-point arithmetic unit, with its associated power and area consumption, can be avoided by using appropriate fixed-point arithmetic and block floating-point operations. It is also shown that a computation intensive graphics method like ray tracing can be used to generate simple images at interactive rates on portable devices. This can be achieved by employing a reconfigurable SIMD architecture on a chip, which trades parallelism for frequency of operation, thus providing significant benefits in power saving, which is essential in