IBM cabling system (ICS)
The basis for IBM to meet the requirements for a universal cabling system was the IBM cabling system ( IVS). This cabling system, which was developed specifically for Token Ring, is called ACS (Advanced Connectivity System) in its further development. The predecessor system, the IVS, consists of several data cable types and a uniform data connector.
The IBM data cable types will be used to replace all mutually incompatible cabling, such as coaxial cabling using RG-62 cable for the IBM 3270 world, Twinax cabling for the S/36 world, twisted conductors (IBM 4700) and multiple twisted conductors (IBM 8100). IBM computer systems use completely different cabling, for example, the 3270/3600/4300 world uses star coaxial cabling based on RG-62 cable with 93 ohm characteristic impedance. The 3250/5080 world, on the other hand, uses RG-6 cable with 75 ohmimpedance, the IBM PC network relies on wideband coax with RG-11 cable with 75 ohm impedance, the /36, /38, and AS/400 series use twinaxial cable with 105 ohm impedance, and the IBM banking system uses two- wire ring cable with 55 ohm characteristic impedance.
Where possible and practical, IBM uses twisted copper pairs with double shielding in its cabling. The second shielding also carries the ground potential. This symmetrical transmission medium is characterized by low electromagnetic interference, low crosstalk and a relatively high possible transmission capacity of up to 125 Mbps. For bridging greater distances or in areas with very strong electrical interference fields, IBM suggests the use of fiber optics. At the same time, this achieves that data security is significantly increased, since fiber optic cables do not radiate and are therefore relatively tap- proof.
The distribution components of the IVS are installed in man-sized distribution frames 19 inches wide or multiples thereof. They contain perforated plates that can be fitted with IVS data connectors from the front and rear.