Really? The H742 power supply: https://gunkies.org/wiki/H742_Power_Supply (well, technically, the associated 'bricks', such as the H744, etc) from about 1972 were switching supplies, so I'm suprised that the much later VAXen (any of them) used linear supplies. Of course, the H744/etc switching supplies didn't use a lot of the techniques used in modern switching supplies to make them small and light (e.g. stepping up the frequency to allow use of a small transformer); the H742 still has a whacking great transformer in it. But they were switching supplies (as we discussed here a while back at some length), not linear. Noel