Removable Storage Media


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In order to be able to securely transport computer data everywhere, removable media has been created, which are mass storage devices designed to be removed from a computer without shutting it down. There are two categories of removable media: those that require a dedicated device and those that do not. For the first category we can cite as peripherals: the diskette, the optical disk (CD, DVD, and Blu-Ray) and the memory card whereas for the second category we find all the peripherals connecting in USB: the USB key and the external disk (HDD and SSD). In this article we will detail each media, making a brief history: their capacity, advantage, and disadvantage as well as their mode of operation and their use. For that, let’s start with the first category, namely those requiring a dedicated device and the first one that existed in this category is the floppy disk.


We will start by studying the very first removable storage device: the floppy disk. It is dubbed the floppy because of its opposition to the hard drive and requires a floppy disk drive to be read.


The first time we hear about floppy is in 1967. Indeed IBM wants to develop a simple and inexpensive system to launch microcode (firmware) in its latest model System / 370. This small computer (8 m³) or rather computer had as a problem its volatile memory (it was necessary to reload all the firmware at each reboot) and required for this a magnetic tape drive, but these bands were very long and the loading time was endless. IBM wanted to be able to easily send these updates at a lower cost. The first floppy disk measured 8 inches (20 centimeters), it could hold 80 KB and equipped the 370 as early as 1971. With the emergence of microcomputers (personal computers) in the 1970s, the 8-inch floppy disk was used as a device. high-speed storage compared to the hard drives of the time. However, this device was very expensive, especially for diskette drives that were more expensive than the computer itself. The maximum size for 8-inch floppy disks was 800 KB in 1973, but the floppy disk’s flaws were its price and also its size, which did not allow for use in desktops.

That’s why it was decided in 1979 to launch the development of a smaller floppy disk, measuring 5.25 inches (13 centimeters) and had a capacity of 110 KB. The floppy disk drive was significantly less expensive. expensive than the 8-inch drive, and it was also the first double-sided floppy disk in 1978, doubling the capacity of the drive (360 KB). It can be noted that the floppy disk drives were able to read on one side only: it was, therefore, necessary to return the floppy disk in the drive to consult the other side of the device and thus be able to access the entire capacity. Its maximum capacity was reached in 1984 with a 1.2 MB floppy, while the current capacity of hard drives was 20 to 40 MB in 1984. 5.25-inch floppies allowed writing and reading and there was a security system to configure them read-only. During the 1970s and 1980s, this floppy disk had the monopoly of storage for personal computers because the hard drives were still too expensive and unreliable. However this floppy disk was still quite large and its storage capacity quite low, which motivated the search for a new version in the late 80s.

Now let’s talk about the floppy disk that everyone knows, the 3.5-inch disk invented by Sony in 1984. This floppy disk was a huge commercial success, thanks in particular to the many computer sales Atari and Commodore that used it: it exceeded in 1985 the 5.25-inch disk. Originally its capacity was 360 KB but eventually, a maximum of 2.81 MB was reached. At that time many computers needed floppy disks to get started and these were produced until March 2011, their replacement being the Zip diskette.

What sets the Zip disk apart from other “normal” diskettes is that there is no disk-like on conventional floppies: it was composed of flash memory, and despite its initial capacity of 100 MB (at most 750), these diskettes have had little success especially because of their price and especially with the arrival of CD-RW (reusable).

Operating method

A floppy disk is a thin, reinforced plastic disk in the center on which a magnetic substrate is applied. The disc is wrapped in a rigid plastic shell. There is internally a cleaning device and externally the reading devices, the protection against writing and the keys. To read the floppy disk you need to have a floppy disk drive and put the device in the right direction. The advantages of this device are the low price, easy transport (the 3.5 inch fits in a pocket) and its lifetime. However, its low storage capacity, its slowness and the risk of data corruption when exposed to magnetic fields or dust that can damage the heads of the drives cause the floppy disk to be abandoned in 2005 for software distribution.

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