My friend's dad has a CNC machine that requires floppy disks to load the design patterns. He's worried that a mechanical failure of the disk drive will eventually be the end of it, rather than the machine itself being obsolete. It's been going strong for almost 40 years now.

As long as it’s not connected to a network and is actually maintained, there’s nothing specifically wrong with Windows 98. Also just make sure the USB ports are shut.

It's amazing even for the cheaper CnC machines in other industries running on Dos or Win95, 98, XP. I use to have to maintain the hardware of these older PCs as the initial outlay to replace the machines was fairly high compared to stress and much lower cost of finding old hardware.

In the end with the modem equivalent CnC machines on the lower end we would only see minimal upgrades to the functions of the machines, versus the updates to the software. Let's me honest that would become obsolete yet again within a few years.

It's the circle of life?

My work used to use (until a project I worked on* to bypass it) a document formatter that lived in a set of chips on an ISA card

ISA slots went rare with Pentium 1/586; were extinct not much later

We had a beige box and a backup beige box. When parts failed the replacements were incredibly expensive (enough it was worth 12*60 pdays of fixing)

(* On resumes, I was totally critical to that project; in reality it was build led, and I was in design)