Xbox was the first console to incorporate a hard disk drive, used primarily for storing game saves compressed in ZIP archives and content downloaded from Xbox Live. This eliminated the need for separate memory cards (although some older consoles, such as the TurboCD, Sega CD and Sega Saturn had featured built-in battery backup memory prior to this). Most of the games also use the hard drive as a disk cache, for faster game loading times. Some games support "Custom soundtracks," another particularly unusual feature allowed by the hard drive. An Xbox owner can rip music from standard audio CDs to the hard drive so players can play their custom soundtrack, in addition to the original soundtrack of Xbox games that support such a feature.
Although the Xbox is based on commodity PC hardware and runs a stripped-down version of the Windows 2000 kernel using APIs based largely on DirectX 8.1, it incorporates changes optimized for gaming uses as well as restrictions designed to prevent uses not approved by Microsoft. A similar approach (PC hardware, stripped-down Windows) was used by the Tandy VIS entertainment system. The Xbox does not use Windows CE due to Microsoft internal politics at the time, as well as limited support in Windows CE for DirectX.
The Xbox itself is much, much larger and heavier than its contemporaries. This is largely due to a bulky tray-loading DVD-ROM drive and the standard-size 3.5 inch hard drive. Because of this, the Xbox has found itself a target of mild derision, as gamers poke fun at it for things like a warning in the Xbox manual that a falling Xbox "could cause serious injury" to a small child or pet. However, the Xbox has also pioneered safety features, such as breakaway cables for the controllers to prevent the console from being yanked from the shelf.
The original game controller design, which was particularly large, was similarly often criticized since it was ill-suited to those with small hands and caused cramping in the hands of some users. In response to these criticisms, a smaller controller was introduced for the Japanese Xbox launch. This Japanese controller (which was briefly imported by even mainstream video game store chains, such as GameStop) was subsequently released in other markets as the "Xbox Controller S", and currently all Xbox consoles come with a "Controller S", while the original controller (known as Controller "0", "The Duke", or "The Hamburger") was quietly discontinued.
Several internal hardware revisions have been made in an ongoing battle to discourage modding (hackers continually updated modchip designs in attempt to defeat them), cut manufacturing costs, and to provide a more reliable DVD-ROM drive (some of the early units' drives gave Disc Reading Errors due to the unreliability of the Thomson DVD-ROM drives that were used). Later generation of Xbox units that used the Thomson TGM-600 DVD-ROM drives and the Philips VAD6011 DVD-ROM drives were still vulnerable to failure that rendered the consoles either unable to read newer discs or caused them to halt the console with an error code usually indicating a PIO/DMA identification failure, respectively. These units would not be covered under the extended warranty.