greg pfister has stated that clusters were not invented by any specific vendor but by customers who could not fit all their work on one computer, or needed a backup. pfister estimates the date as some time in the 1960s. the formal engineering basis of cluster computing as a means of doing parallel work of any sort was arguably invented by gene amdahl of ibm, who in 1967 published what has come to be regarded as the seminal paper on parallel processing: amdahl's law.