Floppy Disk Drive; Table 1-2: Floppy Disk Specifications - DTK Apex 386/33 User Manual

Floppy Disk Drive

With a floppy disk drive you can format and use single, double-sided
or high-density floppy disks.
One double-sided 5.25" floppy disk can store up to 360KB of data.
One double-sided high density 5.25" floppy disk can store up to 1.2MB
of data. One standard 3.5" floppy disk can store up to 720KB of data.
One high density 3.5" floppy disk can store up to 1.44MB of data.

Table 1-2: Floppy Disk Specifications

Note:
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Chapter 1: System Overview
Only high-density floppy disks can be formatted to high
capacities of either 1.2M for 5.25" or 1.44M for 3.5" floppy
disks. You may lose data if you use a low-density floppy disk
formatted for high density.
You can't use a high-density disk in a low-density disk drive.