This is actually the reason we had "turbo" buttons on PCs back then. It wasn't to overclock. Instead, it was to underclock to some backward-compatible CPU speed

This is actually the reason we had "turbo" buttons on PCs back then. It wasn't to overclock. Instead, it was to underclock to some backward-compatible CPU speed that would allow legacy software like that to hopefully work OK. However, I'm not sure how many different compatibility models were being targeted.