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HISTORY: First HDD Form Factor Introductions

From 39-inch to 0.85-inch

The table below has been first published by Disk/Trend and then has been updated by StorageNewsletter.com.

In 1956, the first HDD, the IBM RAMAC, was using 50 coated aluminum disks – or 100 surfaces – one inch thick and 24 inches (610mm) in diameter, for a mere 5MB raw capacity or 4.4 million characters.

But there was also in 1965 a Model 2 Disc Files Series 4000 from Bryant Computer Products, a division of EX-CELL-O Corp., with even larger diameter (39 inches), remembers one of our readers, Vinson Kelley, former Burroughs employee, who said that he is fairly certain that he also saw a 30-inch HDD in his company.

Model 2 Disc Files Series 4000 (Bryant Computer Products
    14 (43MB) or 24 disks (103MB), up to 3,551 pounds,
         900 or 1,200rpm, 50ms to 205ms access time

Since then, the manufacturers always try to reduce the size of the disks and to increase the areal density, and consequently diminish the form-factors of their HDDs to reduce the price of the components and the overall cost of the drives. Record is an incredible 0.85-inch unit launched by Toshiba in 2004, a technology jewel without customers.

But there was some limit. HDD under 1.8-inch form factors didn’t have success as their capacities were too low and the price per gigabyte too high. Flash NAND technology eliminates completely these tiny HDDs.

Now there are only disk drives in 2.5-inch and 3.5-inch form factors. Toshiba was the last manufacturer of 1.8-inch HDDs.

                             One of the largest HDD
  24-inch, 5MB, launched by IBM on September 14, 1956

                          The smallest HDD
0.85-inch, 2/4GB, launched by Toshiba in January 8, 2004

                      Comparison of form factors
                 (8.5, 5.25, 3.5, 2.5, 1.8 and 1″ HDD)
 (Source: superuser)

 39-inch  1965  Bryant
 24-inch  1956  IBM
 1963  IBM
 10.5-inch  1981  Fujitsu
 9.5-inch  1988  Hitachi
 8.8-inch  1984  Hitachi
 6.5-inch  1993  Hitachi
 5.25-inch  1980  Seagate
 3.5-inch  1983  Rodime
 3.0-inch  1996  JTS
 2.5-inch  1988  PrairieTek
 1.8-inch  1991  Intégral Peripherals
 1.5-inch  1991  Ecol.2
 1.3-inch  1996  PicoDisk
 1.0-inch  1998  IBM
 0.85-inch  2004  Toshiba