The current availability of large scientific computers and the alternatives of direct array processors and distributed processors is reviewed. A concise and thorough examination of the relevant aspects of the CRAY-1's hardware which produce the very high computational speeds is presented with reference to the vectorizer. Consideration is given to the CRAY-1 Fortran compiler which is the most important user-orientated software on the system. Attention is paid particularly to invoking vectorization using the compiler. Finally, the results of a study of matrix multiplication and sorting routines on different computers, representing a range of engineering computers, is given as a basis for comparing their performance. It is concluded that the future for large computers seems assured as they fulfil the special requirements of the engineering community.