The present invention discloses a modified computer architecture (50, 71, 72) which enables an applications program (50) to be run simultaneously on a plurality of computers (M1, ...Mn). Shared memory at each computer is updated with amendments and/or overwrites so that all memory read requests are satisfied locally. During initial program loading (75), or similar, instructions which result in memory being re-written or manipulated are identified (92). Additional instructions are inserted (103) to cause the equivalent memory locations at all computers to be updated.