Interchangeable frames, namely, mobile racks and computer backplanes for hard discs; housings for data processing equipment, computers, magnetic and optical data storage apparatus; data storage systems, namely, systems for storage and backup of electronic data either locally or via a telecommunications network for data processing equipment and computers; cabinet systems comprised of telescopic rails, screens and mounting devices, housings and drawers for computer keyboards and screens for holding modular rack housings and accessories; cables for data, sound and video transmission, namely, glass fibre connector cables; power supplies, namely, combinational circuit parts, components, connectors and adaptors, power supply units, transformers and uninterruptible power supplies for computer systems and computer peripheral devices; temperature regulators and sensors, fans and heat sinks for computers and computer peripheral devices; accumulators, in particular rechargeable nickel batteries; data processing equipment, namely, computer peripherals, computer components and motherboards; computer screen filters, computer monitors and input apparatus, in particular keyboards and mice; lamps based on cold light cathode technology; housings for audio equipment, namely, for stereos, speakers, amplifiers, equalizers and crossovers; magnetic and optical data storage apparatus, in particular hard disc drives, CD/DVD drives, floppy disc drives, exchangeable disc drives; electronic reversing switches for input and output apparatus, namely, KVM keyboard/video/mouse reversing switches; network storage systems, namely, systems for storage and backup of electronic data via a telecommunications network for recording and reproduction of digital data