[MS] Just for fun: A survey of write protect notches on floppy disks and other media - devamazonaws.blogspot.com

As you may have noticed, sometimes I waste time gathering useless information. Today we're going to look at write protect notches for floppy disks and other media.

The 8-inch floppy was unusual in that the drive was mounted vertically. You inserted the floppy with the label facing left. The write protect notch was at the top of the leading edge. If you put the floppy on a table with the label in the upper left, the leading edge would be the bottom edge, and the write protect notch would be on the left part of that bottom edge. The presence of a notch made the floppy write-protected, so you started with a write-enabled floppy, and if you wanted to protect it, you punched a notch at just the right spot.

If you placed a 5¼-inch floppy on a table with the label in the upper left, the leading edge would be the bottom edge, and the write-protect notch was on the right edge, near the top. When inserting the floppy into the drive, it would be on the left side near your hand. The presence of a notch made the floppy write-enabled. To protect it, you covered the notch with a sticker. So it was really a write-enable notch, not a write-protect notch.

The 3½-inch floppy had a write-protect hole in the upper right corner when you put the floppy on a table with the label in the upper left, leading edge at the bottom. An open hole made the floppy write-enabled; a closed hold made it write-protected. A sliding door on the underside of the floppy let you decide whether the hole was open or closed. So again, it was technically a write-enable hole, not a write-protect hole.

The Iomega Bernoulli Box was a proprietary system that used cartridges for storage. If you put the cartridge flat on a table, the natural orientation was for the label to be at the bottom, with the leading edge at the top. There was a sliding switch on the bottom left corner to control whether the media was write-protected, but no hole. Instead, the switch had a ⊘ symbol on one side (not 🚫), indicating that moving the slider to that side would write-protect the cartridge.

The last media I used regularly from this era was the cassette tape. The write-protect notch was a recess in the upper left corner covered by a tab, and if the tab was broken, then the cassette was write-protected.

I'm amused that different media had different opinions as to whether the presence of a hole/notch/recess meant that the media was write-enabled or write-protected.

Format	Position when on table	Hole means
8-inch floppy	Bottom edge, left side	Read-only
5¼-inch floppy	Right edge, top side	Writable
3½-inch floppy	Top right corner	Writable
Bernoulli cartridge	Bottom left corner	No hole!
Cassette tape	Top edge, left side	Read-only

Post Updated on March 3, 2026 at 03:00PM
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