3 ms·
Part of that is because each bit stored was so large that you could feel whether it was zero or one by moving a magnet above the disc. That’s exaggerated, but
by Someone 3y ago
Part of that is because each bit stored was so large that you could feel whether it was zero or one by moving a magnet above the disc.
That’s exaggerated, but the first 8” floppy held only about 80 kilobytes (https://www.ibm.com/ibm/history/ibm100/us/en/icons/floppy/breakthroughs https://www.ibm.com/ibm/history/ibm100/us/en/icons/floppy/br...), with tracks that were over half a mm wide (32 tracks/inch), and about 62 bits/mm. It also was read-only.
Reading https://archive.org/details/ibmrd2505ZE/page/n5/mode/1up https://archive.org/details/ibmrd2505ZE/page/n5/mode/1up, that soon become about 250kB. That’s also what DEC’s first ones stored, according to https://en.wikipedia.org/wiki/List_of_floppy_disk_formats https://en.wikipedia.org/wiki/List_of_floppy_disk_formats.
- yomlica8 3y agoI remember reading that there was a lot of data storage "left on the table" with floppy drive tech before it was finally abandoned. They apparently stored bits uniformly across the disk instead of more densely at the edges where distance between the points was greater. Considering how there was a real missing niche for a denser floppy media for a number of years (that allowed things like zip drives to become somewhat common) I found this idea pretty surprising.
- IIsi50MHz 3y agoAlthough single-speed motors were most common, some drives had variable speed motors. In combination with an appropriate disc controller, the rotation could be sped up or slowed down so that bit locations arrived at the read/write head at a uniform rate. Thus you could pack bits as closely on the outer tracks as on the innermost.