Locking the desktop in the filing cabinet

There are two main approaches to running PC applications in a corporate environment: desktop and thin client. In desktop systems, processing takes place on a machine local to the user. Data and applications may be stored centrally, but an autonomous PC placed a keyboard cable's length away from its user does the work. Thin-client systems have a dumb local box that shuttles keyboard, mouse and video signals between the user and a central server.

Desktop blades are a halfway house between the two approaches. Every user has a dedicated PC, kept and managed in a server centre, with a small box on the physical desk that connects to screen, keyboard and so on. The desktop blade PC has its own hard disk and operating system -- typically Windows XP, although in principle it can be any PC OS -- and is connected to the normal network resources such as file and print servers, Internet access and so on through normal networking.

The original blade desktops used special analogue techniques to send the video from the PCs up to a couple of hundred metres along twisted pairs to the user. This meant a minimal amount of modification to the PCs and the software they ran -- from an electrical and software viewpoint, they were just computers with very long leads -- but imposed significant physical restrictions on the scope of the installation. For some specialist applications, where security considerations limit the physical location of the userbase, this is no disadvantage, but it has limited the applicability of the idea in general. The latest generation of blade desktops uses more conventional remote access techniques akin to VNC or other remote control products: this puts input and output into IP packets which can then be switched and routed alongside any other network traffic.

The advantages of a desktop blade configuration are the security and manageability of a thin-client system, coupled with the individual performance guarantees and ability to run a wide variety of software that come with one PC per user. The user -- or anyone else without access to the data centre -- is prevented from walking away with the PC; it's also easy to set things up so that viruses or unauthorised software can't be introduced onto the network, because there is no local storage as standard. However, current blade desktops can be set up to provide USB connectivity to users, which needs careful management regardless of where the processor lives.