In 1983, Sony introduced 90 mm micro diskettes, better known as 3.5-inch (89 mm) floppy disks, which it had developed at a time when there were 4" floppy disks, and many variations from different companies, to replace the then on-going 5.25" floppy disks. Sony had great success and the format became dominant. 3.5" floppy disks gradually became obsolete as they were replaced by current media formats.