Number One Electronic Switching System

<p>The Number One Electronic Switching System (1ESS) was the first large-scale <a href="/facts/Stored_program_control/FXtRRPlr">stored program control</a> (SPC) <a href="/facts/Telephone_exchange/PaRpGm8I">telephone exchange</a> or <a href="/facts/Electronic_switching_system/rqHUmBML">electronic switching system</a> in the <a href="/facts/Bell_System/GspEoeEF">Bell System</a>. It was manufactured by  <a href="/facts/Western_Electric/j15TJJcx">Western Electric</a> and first placed into service in <a href="/facts/Succasunna/r8VG8n7a">Succasunna</a>, <a href="/facts/New_Jersey/pI5k19S7">New Jersey</a>, in May 1965. The <a href="/facts/Switching_fabric/TwfTsu3e">switching fabric</a> was composed of a <a href="/facts/Reed_relay/unwMsTps">reed relay</a> matrix controlled by <a href="/facts/Wire_spring_relay/vPz5IVUb">wire spring relays</a> which in turn were controlled by a <a href="/facts/CPU/Jxp1bqMV">central processing unit</a> (CPU).
</p><p>The 1AESS central office switch was a <a href="/facts/Plug_compatible/TKayPudG">plug compatible</a>, higher capacity upgrade from 1ESS with a faster 1A processor that incorporated the existing instruction set for programming compatibility, and used smaller <a href="/facts/Remreed/unwMsTps">remreed</a> switches, fewer <a href="/facts/Relay/NQcb9usW">relays</a>, and featured <a href="/facts/Disk_storage/hnsXRb5X">disk storage</a>. It was in service from 1976 to 2017.
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Number One Electronic Switching System open-in-new

Number One Electronic Switching System