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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.
- 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
- 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.
- 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.
- 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
- 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
- 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
- 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.
- 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.
Disk Drive Connection Procedure
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