They were using a digital readout on a lathe to indicate the cutting tool's position relative to a workpiece. The positions are detected by encoders mounted on the axis. They feature a numeric display and keyboard. DRO systems are used with milling and boring machines, lathes and Surface grinders.
https://www.aikrondro.com/what-you-must-know-about-using-a-digital-readout-on-a-lathe/ ↗