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Diskless WorkstationA Diskless workstation is a personal computer without any means of non-volatile storage (hence 'diskless'). Not to be confused with Dumb Terminals or cut-down PC's acting as Remote Terminals, a Diskless Workstation is intended to run in a fully 'stand-alone' mode after the initial boot phase. It thus runs a full modern operating system from it's own local RAM. In order to boot such a PC, the Operating System (OS) 'image' has to be provided from some external store - typically across a network link (from a 'Server'), although other means of providing the OS image, such as from removable storage (such as a USB Pen drive) would also qualify, as would directly running a bootable CD containing an OS (such as Knoppix). Needless to say, at least some parts of the OS have to be loaded directly into the PC's memory, part of which is configured as a RAM Disk. Bootstrapping such a PC usually involves a 2 step process, in which a RAM Disk is created, DOS is loaded and then the OS image is fetched and loaded into the RAM disk. A simple Network booted system can be constructed by launching DOS from locally attached floppy disk and using NetBUEI protocols to access a network 'share' containing the OS Image. The 'professional' version is performed via TCP/IP (and a cut down version of DHCP known as BOOTP protocol). This was origionally only available from a special 'BOOT ROM' chip option fitted to the Network card, however BOOTP protocols are now embeded directly into the BIOS of many modern Motherboards and Network Cards). Any applications that the user might wish to use also have to be pre-installed (so that they loaded alongside the OS image). After loading the OS, control has to be passed from the 'bootstrap' program to the OS itself. This is all but impossible with modern Microsoft Operating Systems (such as NT, 2000) so historically Diskless PC's have been limited to UNIX or LINUX based systems (although Windows 98SE has been used with some success, and, in theory at least, Windows XP is supposed to be compatible with Network Booting). Advantages The major advantage of a Diskless PC is that any system changes made during operation (due to user action, worms, virus, etc) are wiped out when the power is removed. This allows use in public access areas (such as Libraries) or in schools etc. where users might wish to experiment or attempt to 'hack' the system. This makes the concept very popular with major corporations (who wish to retain 100% control over their employees use of computers). However such corporations tend to implement Remote Terminals (using Microsoft Windows Terminal Server or other such software), since much lower specification hardware can be used for the client (which essentially acts as a simple 'window' into the central server which is actually running the users operating system as a 'session'). Diskless PC's have also been successfully used in Seti farms where the lack of a hard disk leads to major savings in power comsumption and noise. Disadvantages The fact that nothing is stored locally can also be a major disadvantage. All work in progress has to be saved to some external store, such as a network share or USB Pen drive, etc. This can cause problems later, when a user returns and can not find his work.
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