SP-1 (Stored Program 1) was the name of a computerized telephone exchange (a so-called switching office) manufactured by Northern Electric (later Northern Telecom and now Nortel Networks beginning in 1972) in Canada. It was introduced in 1971 (as stated in a Northern Telecom print ad that is included (page 55) in a history of Nortel, written by Peter C. Newman who was commissioned by Nortel to write it. Copyright is 1995. No ISBN.)
As indicated by the name "Stored Program", the SP-1 introduced computer control to the telephone switching market. (AT&T's #1ESS preceded the SP-1 by several years.)
A central computer controlled the operation of the switch. Switch behavior was determined by the operation of a computer program.
With its use of computer hardware and software control, the SP-1 marked an evolutionary step in telephony design. It was an intermediate form between the previous generation of electromechanical systems and the next generation of fully digital systems. Like the previous generation of systems, the SP-1 was an analog switch that used a special form of mechanical relay (Minibar crossbar switch) to provide the voice connections. The voice signal remained in the analog domain throughout the exchange, with the crossbar switches providing a metallic path to connect the end points of a call together. However the SP1 replaced the previous generation's complex relay-based controllers (markers) with a modern Harvard architecture electronic computer, with separate data and program memories. SSI DTL logic was used throughout. Two types of memory was used - ferrite sheet memory for the CPU and Piggyback Twistor memory for the storage of program and routing information. A number of variations on the base switch were available. A "two wire" version for local service, a four wire version for toll service. Two/four wire versions were also available as was a TOPS variant that was used to provide Operator services. The first four wire switch (four wire-tops, i.e., it provided toll switching and operator services) was placed in service in Thunder Bay circa 1972. The operator service consoles (CRTs) used an Intel 4004 processor.
The next generation of systems evolved from the SP1 design to replace the analog switch with a digital technology. SP-1 proved the feasibility of software-controlled systems for telephony. It set the stage for the introduction of fully digital systems with the development of the DMS (Digital Multiplex Systems) by Nortel in the 1970s. (Nortel's SL-1 (PBX) was Nortel's first fully digital switching system, and it was introduced in service in 1975.)
switch, this, article, does, cite, sources, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, december, 2009, learn, when, remove, this,. This article does not cite any sources Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources SP 1 switch news newspapers books scholar JSTOR December 2009 Learn how and when to remove this template message SP 1 Stored Program 1 was the name of a computerized telephone exchange a so called switching office manufactured by Northern Electric later Northern Telecom and now Nortel Networks beginning in 1972 in Canada It was introduced in 1971 as stated in a Northern Telecom print ad that is included page 55 in a history of Nortel written by Peter C Newman who was commissioned by Nortel to write it Copyright is 1995 No ISBN As indicated by the name Stored Program the SP 1 introduced computer control to the telephone switching market AT amp T s 1ESS preceded the SP 1 by several years A central computer controlled the operation of the switch Switch behavior was determined by the operation of a computer program With its use of computer hardware and software control the SP 1 marked an evolutionary step in telephony design It was an intermediate form between the previous generation of electromechanical systems and the next generation of fully digital systems Like the previous generation of systems the SP 1 was an analog switch that used a special form of mechanical relay Minibar crossbar switch to provide the voice connections The voice signal remained in the analog domain throughout the exchange with the crossbar switches providing a metallic path to connect the end points of a call together However the SP1 replaced the previous generation s complex relay based controllers markers with a modern Harvard architecture electronic computer with separate data and program memories SSI DTL logic was used throughout Two types of memory was used ferrite sheet memory for the CPU and Piggyback Twistor memory for the storage of program and routing information A number of variations on the base switch were available A two wire version for local service a four wire version for toll service Two four wire versions were also available as was a TOPS variant that was used to provide Operator services The first four wire switch four wire tops i e it provided toll switching and operator services was placed in service in Thunder Bay circa 1972 The operator service consoles CRTs used an Intel 4004 processor The next generation of systems evolved from the SP1 design to replace the analog switch with a digital technology SP 1 proved the feasibility of software controlled systems for telephony It set the stage for the introduction of fully digital systems with the development of the DMS Digital Multiplex Systems by Nortel in the 1970s Nortel s SL 1 PBX was Nortel s first fully digital switching system and it was introduced in service in 1975 See also editDMS 100 Electronic Switching System 1ESS switch TXE Stored Program Control exchange SP 1 Technical Bulletin nbsp This article related to telephony is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title SP 1 switch amp oldid 1185188917, wikipedia, wiki, book, books, library,
