UK start-up M-Net Ltd has launched a printer sharer which uses electricity cables in substitution for the more usual local area network wires. The printer sharer sends data from personal computers to printers, via electricity cabling, converting the computer signal into a serial 125KHz radio frequency which is superimposed over the electricity signals running at 50Hz. M-Net reckons the computer is entirely protected from mains electricity as the printer sharer only extracts the signal from the mains, and does not directly use the mains voltage. John Allen, designer of the machine, called the Intelligent Printer Sharer, reckons any worries that mains electricity would get into computers is complete fantasy and likens using the device – in electricity terms – to plugging a VDU or printer into a computer. To prevent data leakage, a filter is fitted to the fuse box. This should stop the data escaping out of the building, or alien information coming into it. The device fits into a personal computer’s Centronix parallel printer slot and must then be plugged into the electricity socket. At the other end another printer sharer is fitted to the printer and also plugged in to the electricity socket. Data is then sent between the two in small packets, to compensate for interference from electrical noise. The data transmission rate is 12,500 bits per second. Any number of printers can be simultaneously driven from the same machine or a polling protocol can direct the data to the first available printer. A total of 30 personal computers can be supported by the printer. Users can specify which printer or printers they wish to use up to a number of eight, which is the maximum that the network can support. M-Net was set up 18 months ago to exploit the technology which was first developed several years ago. The Portsmouth-based company is around 50% financed by Barclays Bank, the balance being privately funded.
