subscribers. BSkyB spent upward of £20 million advertising the new service. In 2004, Sky began to waive the service fee to customers who were subscribers of their premium sport and/or movie channels, and from 2007, the charge was dropped for all subscribers. Sky+ is also built into Sky+ HD digiboxes. A number of hackers have attempted to upgrade the Sky+ receiver, primarily through the installation of larger hard drives to increase recording capacity; instruction manuals and tool kits to do this are widely available. Installing a larger hard drive in the unit is no harder than in a normal PC, but the Sky+ receiver is sensitive to the type of disk installed. Disks with low power requirements and fast spin up times are most likely to be compatible. Hard drives (consumer electronics drives) designed specifically by manufacturers for use with PVRs provide a considerably lower noise level and produce significantly less heat, reducing the need for internal fans to operate as frequently and again cutting down on noise generation. Software is also freely available which facilitates the migration of recorded material from the hard drive to a replacement. However, as of December 2010, this software is incapable of migrating recorded material from a standard definition Sky+ Box to a Sky+ HD box. It is thought that this is due to the planner databases used for Sky+ and Sky+ HD being incompatible. See also Sky (company) Sky+ HD References External links Sky Plus at sky.com Digital video recorders Direct broadcast satellite services Audiovisual introductions in 2001 Sky Group