It all started on Reddit with an image of a rather unusual disc. If you haven't seen it up close, Max shared it in one of his fabulous visual dumps.

But we still have many questions. Where did these 12-inch optical discs come from? Why are they so big? What was stored on them? The adventure takes us to the mid-80s and throws us into the waters of WORM technology, specially designed for archiving large amounts of data…

The time machine takes us to some point between 1984 and 1985, when MS-DOS 3.0 was in its infancy, and 20-megabyte hard drives were carried on the shoulder. On the other side of the world, the Japanese company Maxell (Makuseru Kabushiki-gaisha) began commercializing its 12-inch optical discs under the OC301 family. Believe it or not, we can still find some of these discs online, and there's always one that goes viral on social media. What was so special about them?

Getting to know 12-inch optical discs

12-Inch Optical Discs: How Gigabytes Were Stored in the '80s
12-inch optical discs

The viral photo shows us a Maxell OC301-2, an "optical disc cartridge" double-sided, with a reported capacity of 2.62 GB.

12-Inch Optical Discs: How Gigabytes Were Stored in the '80s
The reported capacity is 2.62 GB

The available information suggests that these discs were processed in Hitachi-Filenet units, but I haven't found any images of them so far. What we do know is that they are WORM discs, or Write-Once-Read-Many. In other words, once you wrote something on their surface, the storage was permanent, with no possibility of modifying or deleting previous data.

12-Inch Optical Discs: How Gigabytes Were Stored in the '80s
Compared to a floppy
12-Inch Optical Discs: How Gigabytes Were Stored in the '80s
The disc outside its cartridge, next to a DVD

Logically, WORM discs/cartridges went through several evolutionary jumps. For example, Maxell released the OC321-2, with a maximum capacity of 7 gigabytes (3.5 GB per side). Sony never ignored this market, and from the beginning offered its own 12-inch solutions, among which the Sony WDD-931 write unit stands out.

12-Inch Optical Discs: How Gigabytes Were Stored in the '80s
The Maxell OC321-2 raised capacity to 7 gigabytes. Each cartridge weighs 1.2 kilograms.
12-Inch Optical Discs: How Gigabytes Were Stored in the '80s
Sony had its own 12-inch discs and recorders. In the image, the Sony WDD-931 unit.

And outside the corporate world, the public had access to WORM units like the IBM 3363, which used more compact 200-megabyte discs/cartridges. As you can imagine, the unit cost a fortune (over $2,000 in the '80s), but the price per cartridge was much lower compared to a hard drive.

12-Inch Optical Discs: How Gigabytes Were Stored in the '80s
The IBM 3363 unit, and its 200 MB optical disc

From libraries to health centers and government agencies, 12-inch optical discs with WORM technology had their time and place, but were slowly replaced by superior options in every way, with greater speed, greater capacity, and the possibility of altering data. Today they are a rarity, but they definitely deserve a place in any collection.

Sources: Reddit, Engadget Japan, Weird Old Tech.