MODUK DEF STAN 21-24: PART 4 PDF

Introduction 

NES 1024, 1026, and 1028 cover the technical requirements for interfacing to current warship combat systems using the CSH or TWSH. For equipment that will interface to these systems the standards are Category 1, mandatory, but for systems and equipment relating only to new platforms the standards should be considered as Category 2. 

This NES defines a standard interface between computers and intelligent peripherals which implement the protocols of a digital communications system such as a data highway, local area network or point-to-point system. The standard embraces both an electrical and a software interface. 

This standard makes it possible to interface a given computer to different communications systems. Once the standard interface is supported by a computer, the hardware and software development involved in changing the communications system is much reduced.

Similarly, once a communications unit has been designed for a given communications system, that design is readily applicable to all those computers that support the standard interface. Although hardware compatibility is unlikely, only the reengineering of a proven design will be necessary.

Figure 1 shows examples of the NES 1024 concept. It shows a terminal unit (constituting the intelligent peripheral) connected to a host computer consisting of a central processing unit and a memory. The interface between the terminal unit and the host computer is of the direct memory access type (DMA).