Search results
Results from the WOW.Com Content Network
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.
Connection was made via a crossbar switch. A SP1 2-wire variant was also available that provided Centrex services. A version of the SP-1 ESS that could provide both 2 & 4 wire services was also built. The first instance was installed in Vegreville Alberta in 1976 or 1977. SP1 4-Wire (Toll)
Plug-in extension kits are available for customers with this type of installation. The two wires from the exchange are denoted the B leg at −48 V relative to ground when the line is not in use and the A leg which is near ground potential when the line is not in use. The A leg goes to pin 5 and the B leg to pin 2 in the master socket ...
The 1AESS central office switch was a plug compatible, higher capacity upgrade from 1ESS with a faster 1A processor that incorporated the existing instruction set for programming compatibility, and used smaller remreed switches, fewer relays, and featured disk storage. [2] It was in service from 1976 to 2017.
ASME Y14.44-2008 [1] and IEEE 315-1975 [2] define how to reference and annotate components of electronic devices. It breaks down a system into units, and then any number of sub-assemblies. The unit is the highest level of demarcation in a system and is always a numeral.
A telephone switch is the switching equipment of an exchange. A wire center is the area served by a particular switch or central office. A concentrator is a device that concentrates traffic, be it remote or co-located with the switch. An off-hook condition represents a circuit that is in use, e.g., when a telephone call is in progress.
For instances where the full-duplex nature of SPI is not used, an extension uses both data pins in a half-duplex configuration to send two bits per clock cycle. Typically a command byte is sent requesting a response in dual mode, after which the MOSI line becomes SIO0 (serial I/O 0) and carries even bits, while the MISO line becomes SIO1 and ...
Self-ligating brackets are defined as "a dental brace, which generally utilizes a permanently installed, moveable component to entrap the archwire". Self-ligating brackets have also been designed which do not require a movable component to hold the wire in place. [1] Self-ligating braces may be classified into two categories: Passive and Active ...