Process Eng

I have a pair of old laptops I’m reviving – Compaq Armada SB 5233DMT with Windows 98SE. One is working fine and the other does not see the CD-ROM drive. Compaq’s BIOS on the hard drive is a peculiar design which I thought was part of the problem so I mirrored the good drive to the questionable drive to make all things equal. I’ve swapped the CD-ROM drives – they both work fine in the “good” laptop and they spin up in the “problem” laptop but the drive is not visible anywhere – Explorer does not show a drive letter and Device Manager does not list a CD-ROM device. Can anyone solve this riddle for me? I don’t want to believe that there is a failed chip on the motherboard. Any suggestions? Any good troubleshooting utilities? Thanks Roy