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[Previous] [Up] [Top] [Contents] [Back]Chapter 3 Functional Description
The COM9026 is used to implement the ARCNET interface. This device has a microprocessor interface with low-overhead software requirements. It establishes the network configuration, and automatically re-configures the network as new nodes are added or deleted from the network. The 8-position DIP switch on the CC121 module is used to select the ARCNET node ID.
The CC121 module supports three ARCNET medium interfaces, that all have specific advantages for different environments. The RG-58 coax cable is the most often used medium, and uses a standard BNC connector on the front panel. Onboard cable termination has been implemented and can be selected with a jumper.
The lowest cost network medium is a telephone twisted pair cable, and uses the P2 connector for connection to the network.
Dual-Port Memory
The data buffer, used by both the microprocessor and protocol controller to transfer data packets, has been implemented as a dual-port RAM. This memory configuration dramatically improves the memory access time, because the VMEbus master can transfer data packets to/from this memory using high-speed 16-bit transfers.
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