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Floppy Disk Drive Connection Procedure

This procedure provides instructions for making the power and interface connections to a floppy disk drive. This procedure deals with the connection of a single drive in either a single or dual floppy configuration. This procedure does not deal with the physical installation of the drive; for instructions on installing the drive, refer to this procedure.

Procedure Overview:

• Difficulty Level: 2 (Low).
• Risk Factor: 2 (Low).
• Hardware Required: None.
• Software Required: None.
• Time to Perform: 5 minutes or less in most cases.
• Preparation / Warnings:
  • If you have not already done so, please read the section on general installation and assembly tips. Pay particular attention to the notes about connecting cables.
  • I assume that you are using industry standard drives and an industry standard floppy cable, which should have a "twist" in seven of the wires in the middle of it. See here for more on the cable. If you are using non-standard equipment you will probably need to set jumpers. I do not deal with this here because it is unnecessary 99.9% of the time.
  • 3.5" floppy disk drives use the smaller mini-plug usually provided on modern power supplies. Adapters are available for a couple of bucks for use in older systems.
  • Obviously, the floppy disk drive must be installed in the system case before you begin.

Procedure Steps:

1. Attach Power Cable: Attach one of the power-supply power connectors to the drive. It may take a little bit of force to get one of the standard, large four-wire connectors into a 5.25" drive; you may have to wiggle the connector a bit to get it in. The connector is keyed, so it can only go in one way. 3.5" drives use a smaller mini-plug, which is also keyed but easier to attach.
2. Attach Interface Cable: Attach the interface cable to the drive. How this is done specifically depends on what sort of drive you are using and whether this is the first or second drive in the system. Follow these general instructions (refer here for a full explanation of how the floppy cable works):
   • The standard floppy cable has a twist in the middle of it. Connect the drive that you want to be A: after the twist; the drive before the twist is B:. For standard drives, do not change any jumpers. Just use the positioning on the cable. If you are installing a new drive as A: and moving the existing drive to B:, just change which connectors on the cable are attached to which drive. Note that if the drives have been swapped in the system BIOS, these rules about A: and B: will be reversed.
   • Most 3.5" drives have a set of pins for their interface to the cable, and most 5.25" drives use a card-edge connector, sort of like the connector on an expansion card. Most floppy cables have a pair of connectors, one of each type, both before and after the "twist". Use only one or the other in each pair. Some cables only have the pin header connector and you will have to change the cable if you need the card-edge connector type.
   • The single connector by itself at the opposite end of the cable goes to the motherboard or floppy controller.
   • Always make sure to line up pin 1 of each floppy connector with pin 1 of the motherboard, by attaching the cable so that the red wire on one edge of the ribbon cable connects to pin 1 of each device. On some drives it can be hard to figure out which end of the header is pin 1, which is why I recommend that you examine the drive before physically installing it.
   • Many 3.5" floppy drives today are not keyed to prevent upside down connection of the floppy drive cable. This means that it is possible to connect the cable upside-down, and then of course the drive will not work. In most cases this will not cause permanent damage. If when you boot up the PC the floppy drive activity LED comes on and stays on, this is a dead giveaway that you have done this. Reverse the connector.
3. Double-Check Connections: Check over the connections you just made to ensure that they are correct. Make sure you haven't accidentally knocked anything loose.

Next: Hard Disk Drive Connection Procedure

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