[en] The Stanford Linear Accelerator Center is a single purpose laboratory operated by Stanford University for the Department of Energy. Its mission is to do research in High Energy (particle) physics. This research involves the use of large and complex electronic detectors. Each of these detectors is a multi-million dollar device. A part of each detector is a computer for process control and data logging. Most detectors at SLAC now use VAX 11/780s for this purpose. Most detectors record digital data via this process control computer. Consequently, physics today is not bounded by the cost of analog to digital conversion as it was in the past, and the physicist is able to run larger experiments than were feasible a decade ago. Today a medium sized experiment will produce several hundred full reels of 6250 BPI tape whereas a large experiment is a couple of thousand reels. The raw data must first be transformed into physics events using data transformation programs. The physicists then use subsets of the data to understand what went on. The subset may be anywhere from a few megabytes to 5 or 6 gigabytes of data (30 or 40 full reels of tape). This searching would be best solved interactively (if computers and I/0 devices were fast enough). Instead what we find are very dynamic batch programs that are generally changed every run. The result is that on any day there are probably around 50 to 100 physicists interacting with a half dozen different experiments who are causing us to mount around 750 to 1000 tapes a day. This has been the style of computing for the last decade. Our going to VM is part of our effort to change this style of computing and to make physics computing more effective