Up for sale are a lot of (6) 3.5 inch HD hard covered floppy discs. they are a High Density (HD) floppy disk with a capacity of 1.44 MB.
Introduced as a standard data storage medium, these vintage magnetic storage medium were highly popular from the mid-1980s through the late 1990s. These discs remain a classic icon of retro technology.
What you see on each disk includes:
The central metal hub: Used by the computer's floppy drive to spin the magnetic disk inside.
The sliding metal shutter: Protects the delicate magnetic storage tape beneath it when the disk is not inside a drive.
The code stamped on the back of each disc is a manufacturer date code and batch number.
These alphanumeric strings break down into specific production details. Generally, a code formatted like this translates to:
The manufacturing plant: The initial letters or numbers often indicate the specific factory or assembly line.
The date of production: A combination of the numbers represents the year, month, and day the plastic shell and magnetic disk were assembled.
The codes point to the white disks being made made in 1987 and the black disks were made in 1995.
Key Characteristics & Mechanics Visible:
The Metal Shutter: The rectangular metal slider at the top protects the delicate magnetic disk inside from dust and fingerprints. When inserted into a computer's floppy drive, a mechanical lever slides this piece over to allow the drive's internal heads to read or write data. The stylized "HD" logo engraved into the plastic casing right next to the metal slider indicates the disks are High Density.
High Density" (HD) refers to a major upgrade in how tightly data can be packed onto the disk's internal magnetic surface compared to its predecessor, "Double Density" (DD). Because the data is packed much closer together, a standard 3.5-inch HD disk holds 1.44 MB of data, which is exactly double the capacity of a DD disk (720 KB). The transition from Double Density to High Density involves a few key differences:
Magnetic Material HD Disks: Use a much higher-grade magnetic coating (typically cobalt-doped iron oxide). This specialized material allows the magnetic particles to retain their charge even when squished incredibly High Density (HD) floppy disk with a capacity of 1.44 MB. a lower-coercivity magnetic material. If you try to write data at high density onto a DD disk, the magnetic fields are too weak, and the data will quickly corrupt or bleed together.
Drive Technology:
To read and write the smaller, more tightly packed data tracks on an HD disk, floppy drives had to be upgraded with more precise read/write heads and stronger magnetic write currents.
The manufacturer of this disk is Sony, though it may have been sold under a different brand name like Maxell, Verbatim, or Memorex. Sony pioneered the 3.5-inch floppy disk format and had massive manufacturing plants that produced disks both for their own retail brand and as an Original Equipment Manufacturer (OEM) for competitors. You can identify Sony's specific manufacturing footprint by two distinct physical traits on the plastic shell: The Font and Style of the Date Code. The unique, narrow, dot-matrix style engraving of the codes is signature to Sony factories in the 1980s and 1990s. The Injection Mold Circle: The small, circular indentation located just to the right of the date code is a direct artifact of the plastic injection molding machinery Sony used to press their floppy shells.
Sony supplied many other companies with unbranded discs.