IBM Corp has committed itself to data transmission at 100Mbps over shielded twisted pair cabling. It has unveiled a suite of new products and gained endorsements for the technology from 10 large industry players in an effort to get it accepted as a standard. The SDDI technology is being considered by the American National Standards […]
IBM Corp has committed itself to data transmission at 100Mbps over shielded twisted pair cabling. It has unveiled a suite of new products and gained endorsements for the technology from 10 large industry players in an effort to get it accepted as a standard. The SDDI technology is being considered by the American National Standards Institute as the standard for this type of transmission, but to add credibility to the bid, the combined forces of Advanced Micro Devices Inc, Chipcom Corp, Madge Networks Inc, Motorola Inc, National Semiconductor Corp, Network Peripherals Inc, Sumitomo Electric Corp, Synoptics Communications Inc, SysKonnect Inc and Technictrol Inc have thrown their weight behind it. However, whether the bid is successful remains to be seen. ANSI’s initial view was that rather than having two standards for Shielded and Unshielded Twisted Pair, one technology encompassing both types of cable should be found. The hitch is that transmitting data at 100Mbps over unshielded twisted pair is far more problematic than over shielded cable: complex encoding schemes are required, for the simple reason that the untwisted variety becomes an annoyingly efficient radio transmitter without them. The 11 are arguing that to lump both together is to unnecessarily complicate shielded requirements, and that there should be a different specification for each. A parallel bid – from the Unshielded Twisted-Pair Forum which has the backing of Apple Computer Inc, AT&T Co, British Telecommunications Plc, Crescendo Communications Inc, Fibronics Inc, Hewlett-Packard Co and Tandem Computers Inc’s Ungermann-Bass – is trying to establish a standard. Whatever ANSI’s decision, IBM has nailed its colours to the mast with its new products, billed as a low-cost way to enter the high-speed market. The 8240 is a concentrator supporting both FDDI and SDDI; it comes with a choice of two modules – one for each type of cable – and can connect up to 24 devices to a 100Mbps network. The base unit is UKP10,030, the optical fibre module costs UKP4,577 while the shielded twisted pair equivalent is UKP3,017. The FDDI Fibre Base Adaptor/A is UKP3,000 and it connects PS/2s to the 8240, while the FDDI Fibre Extender Adaptor/A enables PS/2s to connect directly to the optical fibre backbone, or to more than one concentrator simultaneously to create alternative paths for information. The Extender is UKP1,500. The two comparable products for shielded twisted pair – the FDDI Copper Base Adaptor/A and the Copper Extender Adaptor/A – are priced at UKP2,650 and UKP1,130 respectively.