Floppy Disk Hack: Scissors Double Storage

This article explains the famous floppy disk hack where cutting a notch in a 5.25-inch diskette with a pair of scissors doubled its usable storage capacity. You will learn exactly how the write-protect notch worked, why cutting it doubled capacity, and how to do it safely on the rare occasions you might still need to.

The Notch Trick

In the early 1980s, 5.25-inch floppy disks were sold in two flavors: single-sided (usually 160–180 KB) and double-sided (usually 320–360 KB). The only physical difference between them was the presence of a small square notch on the top-right edge of the jacket. Double-sided disks had the notch; single-sided disks did not.

That notch was the write-protect mechanism. When the notch was open, the drive’s sensor could see light through it, and the disk was writable. When the notch was covered with tape, the sensor was blocked, and the disk became read-only. The trick: a single-sided disk already had magnetic material on both sides; the drive was simply told to only use one side. By cutting a notch into a single-sided disk, you tricked the drive into thinking it was a double-sided disk, allowing it to read and write the second side. This effectively doubled your storage.

Why It Worked

The floppy disk itself was a round piece of flexible magnetic film inside a square cardboard jacket. Both sides of that film were coated with magnetic oxide. The drive had two read/write heads, one for each side. The drive determined which side to use based on the disk’s label and the notch. A single-sided disk was formatted with only one side in use, but the second side was physically identical and fully usable.

Cutting the notch was a hardware hack that changed the disk’s identity. The drive’s sensor saw the hole, assumed it was a double-sided disk, and enabled both heads. The result was that you could format and use the second side, doubling your storage from 180 KB to 360 KB (or from 160 KB to 320 KB, depending on the disk standard).

How to Do It

If you have an old 5.25-inch disk and a drive that still works, here are the steps:

1. Check the disk’s label to confirm it’s single-sided (look for “SS” or “Single Sided”).
2. Place the disk on a flat surface with the label facing up and the write-protect notch (if any) on the top-right.
3. If there is no notch, use a pair of scissors or a hole punch to cut a small square notch in the top-right edge, about 5 mm deep and 10 mm wide. The exact size doesn’t matter as long as it lets light through.
4. Remove any debris from the cut.
5. Insert the disk into the drive and format it as double-sided (e.g., with the FORMAT A: /U command in MS-DOS).

Important: This hack only works on 5.25-inch disks. 3.5-inch disks have a sliding shutter, not a notch, and the media is often truly single-sided (the other side is blank). Cutting a 3.5-inch disk will not double its capacity.

Risks and Caveats

The hack was not without risks. The second side of a single-sided disk was not always tested by the manufacturer, so it might have defects. Also, the drive’s head alignment for the second side could be off, leading to read/write errors. Many users found that the second side worked fine, but some disks were unreliable.

Another risk: cutting the notch could damage the disk if you cut too deep or if the cardboard jacket was cracked. Always cut carefully and check that the disk still spins freely.

Finally, the hack was only useful with drives that supported double-sided disks. If your drive was single-sided, the hack wouldn’t help.

Why It Became Obsolete

By the mid-1980s, double-sided disks became the standard, and single-sided disks were rare. The cost difference was minimal, so the hack lost its economic appeal. Later, 3.5-inch disks with a capacity of 1.44 MB made the hack irrelevant. Today, floppy disks are obsolete, but the hack remains a classic example of clever hardware modification.

Frequently Asked Questions

Can I do this with 3.5-inch disks?

No. 3.5-inch disks use a sliding metal shutter for write protection, not a notch. More importantly, the magnetic media inside is often single-sided; the other side is blank. Cutting the shutter won’t make the blank side usable.

Did the hack work on all 5.25-inch disks?

It worked on most, but not all. Some single-sided disks had a different magnetic coating on the second side, or the second side was not polished. In practice, the success rate was high, but not 100%.

What was the actual capacity after the hack?

It doubled the capacity. A single-sided 5.25-inch disk typically held 160 KB (in some formats) or 180 KB (in others). After the hack, it became 320 KB or 360 KB, respectively.

Did you need special scissors?

No, any sharp scissors or a hole punch worked. The key was to make a clean cut that didn’t damage the disk.

Is this hack still useful today?

Only if you have vintage hardware and a need to maximize storage on old disks. For modern use, it’s a historical curiosity.

Could the hack damage the drive?

No, the hack was safe for the drive. The drive simply saw a notch and enabled both heads. The only risk was to the disk itself.

Related

• Smart Bulbs and Wi-Fi Extenders: Do You Need One?
• Home Theater Power Managers: Do You Need One?
• Recreate Recovery Partition Mac: Full Guide