The technological resources and know how required for modern drive development and production mean that as of 2007, over 98% of the worlds HDDs are manufactured by just a handful of large firms: Seagate (which now owns Maxtor), Western Digital, Samsung, and Hitachi. Dozens of former HDD manufacturers have gone out of business, merged, or closed their HDD divisions; as capacities and demand for products increased, profits became hard to find, and the market underwent significant consolidation. All hard drives share a basic structure and are composed of the same physical features. However, not all hard drives perform the same way as the quality of the parts of the hard drive will affect its performance. The first notable casualty of the business in the PC era was Computer Memories Inc. or CMI; after an incident with faulty 20 MB AT disks, CMIs reputation never recovered, and they exited the HDD business. Another notable failure was MiniScribe, who went bankrupt after it was found that they had engaged in accounting fraud and inflated sales numbers for several years. Many other smaller companies also did not survive the shakeout, and had disappeared in early 90s. Their claim to fame was creating a new 3″ form factor drive for use in laptops. Quantum and Integral also invested in the 3″ form factor; but eventually ceased support as this form factor failed to catch on. Also, external hard disk drive is used in replacement with internal hard drive. Few features of external disk drive are as follows: The internal structure of external hard disk drives is similar to normal hard disk drives; in fact, they include a normal hard disk drive which is mounted on a disk enclosure. In a 2007 PC Magazine article comparing the top 10 external hard drives, they found the cost per gigabyte value varied between 0.30 0.50 USD. More external hard drives retain the platters and moving heads of traditional hard drives they are much less tolerant of physical shocks than flash based technology. Larger models often include full sized 3.5 PATA or SATA desktop hard drives, are available in the same size ranges, and generally carry a similar cost. More pricey models, especially small USB powered pocket hard drives, generally cost considerably more per gigabyte and are limited to the sizes available for smaller drives intended for laptop and embedded devices. Modern external hard drives are compatible with all operating systems supporting the relevant interface standards they operate with, such as USB MSC. These standards are supported by all major modern server and desktop operating systems and many embedded devices.