I had installed a floppy drive from one coputer to another...ME to XP o/s...my computer does not see or have Drive A...I had used the floppy cable the was connected to the mobo ...it even has a picture of a floppy disk on the cable Thanks.
Check the bios as stated. Also, make sure all the pins line up correctly (if there are pins showing, the cable isn't on correctly). Make sure the cable is installed in the proper direction (if the drive light stays on constantly, the cable is on there backwards). If the cable has multiple connectors, use the ones on either end (the one in the middle is for a secondary floppy device). Remember to connect the power, I know its obvious but sometimes its the simple things that get you.