NEC 128 manual System Control, Line Interface

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Technical Description 3-3

System Control

The System Control circuit manages the many separate functions of VisuaLink. This circuit provides control for the Codec and other devices. Various control devices can be used for VisuaLink: VisuaLink infrared remote control, any analog phone, an NEC VoicePoint+ speaker phone, and a Personal Computer (connected via the RS-232 serial ports).

System Control provides three videoconference control modes:

H.281 for multi-location and far-end camera control.

H.243 Multipoint Chairman for multi-location chairman control and browse functions.

T.120 Multipoint Data Sharing & Collaboration compliance for multi-location data conferencing.

Line Interface

This circuit provides the correct electrical and protocol connections for ISDN-1 BRI line interface. VisuaLink 128 supports one NT-1 (Network Terminal Devices) terminated ISDN-1 BRI line connection.

The VisuaLink 384 has an on-board IMUX (Inverse Multiplexer) which supports ISDN BRI bonding calling. This allows users to connect up to three NT1-terminated ISDN BRI line connections to VisuaLink. This makes it possible to combine three signals from three separate BRI lines into one contiguous data channel.

VisuaLink 128/384 General Description

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Contents VisuaLink 128/384 NDA-24229, IssueLiability Disclaimer Contents Specifications Overview IntroductionFeatures Phone-Like Dialing Echo CancellerCamera Control Videoconferencing CompliancePBX Connectivity Field UpgradableApplications Isdn BRI VisuaLink Documentation Introduction VisuaLink 128/384 General Description Roll-About Desktop PC Gateway Application ConfigurationsEasily moved, use in active locations Roll-AboutVideo Cabinet Roll-About ComponentsVisuaLink 128/384 Video MonitorMicrophone Motion Video CameraCable Kit OptionsAlso available with control software Desktop PCVideo Capture Board Desktop PC ComponentsCCD Desktop Camera NT1 Graphics Camera D30 Camera AT841/INT Microphone VisuaLink Director SoftwareLaptop PC option Personal Computer RequirementsVisuaLink & ViewPoint VBX Gateway GatewayVisuaLink Direct Connect Gateway System Control Technical DescriptionVideo & Audio Interfaces Echo CancellerCodec VideoLine Interface System ControlMore on H.320 Videoconferencing Picture ResolutionVideo Frame Rate Audio Video ProcessingData Transmission Rate For ExampleTechnical Description VisuaLink 128/384 General Description Installation Requirements Installation & MaintenanceMaintenance Requirements General Specifications SpecificationsPage General Parameters Parameter VisuaLinkUnit Size Line Interface External Interface ParametersSerial VisuaLink Unit Control Operating Modes & FeaturesCall Dialing Originating Modes Incoming Call Answer ModesLine Connect Modes Line Interface ControlVideo Display/Output Modes Audio Control ModesMulti-Point Conference Control MaintenanceSerial Port Modes VisuaLink 128/384 General Description

128 specifications

The NEC 128 is a remarkable microprocessor that represents a significant leap in technological innovation during its time. Introduced in the early 1980s, this processor was designed to meet the demands of increasingly sophisticated computing tasks, primarily aimed at the burgeoning field of personal computing and embedded systems.

One of the standout features of the NEC 128 is its 16-bit architecture, which was quite advanced for its era. This architecture allows for a greater data throughput, enabling the handling of larger data sets and providing improved performance over its predecessors. The NEC 128 operates on a clock speed that typically ranges from 4 to 8 MHz, making it capable of executing instructions efficiently and swiftly, which was crucial for running more complex applications.

The processor is built using CMOS technology, which offers significant advantages in terms of power consumption compared to earlier bipolar technology. This characteristic made the NEC 128 not only suitable for desktop computing but also an appealing choice for battery-operated devices, enhancing its versatility. The use of CMOS allowed for a reduced heat output, contributing to the reliability and longevity of devices powered by this microprocessor.

Another noteworthy aspect of the NEC 128 is its support for a variety of addressing modes. This flexibility enables programmers to write more efficient and compact code, optimizing the use of memory resources. By supporting both immediate and indirect addressing, the NEC 128 allows for more dynamic programming, which is essential for developing applications that require real-time processing.

The processor's architecture also includes a robust instruction set that facilitates arithmetic operations, logical operations, and control flow management. This comprehensive instruction set is instrumental for developers, as it provides the necessary tools for creating a wide range of applications, from simple utilities to more complex software systems.

In summary, the NEC 128 microprocessor is characterized by its 16-bit architecture, efficient CMOS technology, and a versatile instruction set, making it a compelling choice for its era. Its combination of performance, power efficiency, and flexibility positioned it as a formidable player in the personal computing market and laid the groundwork for future advancements in microprocessor technology. With its various applications and features, the NEC 128 remains a noteworthy chapter in the history of computing.