[snip]

Installed the A11 version of the BIOS. But it didn't change anything. The Sony CDROM drive was still listed as "unknown". Some combination of Windows and the controller is jacked up. I have another old CDROM drive: Samsung SC-140b. It works in the PC but only in PIO mode. Windows initially detected it and set the primary controller mode Multi-Word DMA Mode 2. But once I put in a CD the PC locked up. I'm glad I have an external USB DVD drive. I give up on work with this old technology. Thank you everyone for your comments. Out!