I installed a 5 1/4" chinon FR-506 double density drive (from an old 386 machine) into my old Pentium. There was only one plugin on the drive. I also took a double-speed CD ROM drive from the 386 and installed it in the Pentium.Windows 95 recognized the CDROM but not the 5 1/4". I have a huge library of 5 1/4" diskettes and thought for fun I could use the drive in the Pentium. I have used Control Panel and tried the ADD NEW HARDWARE but it didn't work. I see jumpers on the drive but I don't know what settings for them. Chinon doesn't support the drive.
Does anyone have any suggestions? Thanks.

and you did enter pc bios and tell it you had a 5.25" floppy drive right? and you did tell it your drive was 1.2 mb right? It is a 1.2 mb drive isn't it?

depending on how the drive jumpers are configured, you either need a floppy cable with or without a twist in it

one or the other will work if the drive is set as the only drive (a)
to use this drive in a system with a existing drive as a B: you will either need to use a cable with a twist or reconfigure the drive as a B: unit on a cable without a twist

and you did enter pc bios and tell it you had a 5.25" floppy drive right? and you did tell it your drive was 1.2 mb right? It is a 1.2 mb drive isn't it?Yes I entered the BIOS but selected 360K not the 1.2mb. After I did that and saved it, the machine then came up with a FLOPPY ERROR and informed me to go back in the BIOS again.

Then you apparently do not have a 360kb drive, it's defective, or as damien suggested, you have a cable or jumper problem.