10BASE2: Difference between revisions

During the mid to late 1980s, this was the dominant {{val|10 |ul=Mbit/s}} Ethernet standard.

The name ''10BASE2'' is derived from several characteristics of the physical medium. The ''10'' comes from the transmission speed of 10 [[Megabit per second|Mbit/s]]. The ''BASE'' stands for [[baseband]] signaling, and the ''2'' for a maximum segment length approaching 200 m (the actual maximum length is 185 m).

10 Mbit/s Ethernet uses [[Manchester code|Manchester coding]]. A binary zero is indicated by a low-to-high transition in the middle of the bit period and a binary one is indicated by a high-to-low transition in the middle of the bit period. Manchester coding allows the clock to be recovered from the signal. However, the additional transitions associated with it double the signal bandwidth.

As is the case with most other high-speed [[Transmission line|buses]], Ethernet segments have to be [[Electrical termination|terminated]] with a [[resistor]] at each end. Each end of the cable has a {{val|50 [[ohm (unit)|ohm]] (ul=Ω)}} resistor attached. Typically this resistor is built into a male [[BNC connector|BNC]] and attached to the last device on the bus. This is most commonly connected directly to the T-connector on a workstation.{{efn|A few devices such as Digital's DEMPR and DESPR have a built-in terminator and so can only be used at one physical end of the cable run.}} If termination is missing, or if there is a break in the cable, the [[alternating current|AC]] signal on the bus is reflected, rather than dissipated, when it reaches the end. This reflected signal is indistinguishable from a collision, so no communication can take place.