Ask HN: Who's still keeping a DOS machine up because the business depends on it?

I'm researching how businesses still rely on legacy DOS systems: dBase/Clipper/CLARION/Paradox or other DOS RAD environments on period hardware, CNC mills/spectrometers/microscopes controlled by ISA cards (bespoke or GPIB), and parallel port dongles. I want to hear your experiences, not to sell anything, but to explore an idea for keeping these running on modern hardware.