Some time ago, I thought it would be useful to understand exactly what is the difference between CD-ROMs recorded in the old High Sierra format versus the ISO 9660 standard. This was in part spurred by the fact that I have a number of CD-ROMs/images that use the High Sierra format (Microsoft Programmer’s Library, some IBM Developer Connection issues, OS/2 Warp 4, and more) that both macOS and Windows 10 refuse to mount. The other part of my motivation was the usual insatiable curiosity.
I had no idea about the existence of this different format.
Doubtless ditching CD-ROM High Sierra Support was a Microsoft attempt to remove kruft along with hiding the ability to mount a floppy drive. I don’t know about built in but USB floppy drives still work. I have no idea about external CD-ROM format support. Of things to remove these seemed like an odd choice.