VHDL AND SYNTHESIS TOOLS PROVIDE A GENERIC DESIGN ENTRY PLATFORM INTOFPGAS, PLDS AND ASICS

Field programmable gate arrays, programmable logic devices and applica tion specific devices such as masked programmable gate arrays have now reached such a degree of complexity that it is impossible for a desig ner to effect a design in silicon without the support of computer aide d design tools. Much of the software available is target device specif ic, in other words the designer must use tools that are specifically t ailored toward the architecture and technology into which the design w ill finally be realized. The development of VHDL as a general design e ntry tool was sponsored by the US Department of Defence (DoD) to overc ome the problem of a design becoming target dependent. In this way a d esign may be created in VHDL and the target technology chosen after th e fact. The design may then be synthesized into a target technology by the application of synthesis tools. However, if that technology becam e obsolescent or impossible to procure a new target technology may be chosen and the synthesis tool re-applied to migrate the same design in to the new device, thus forgoing the task of a complete logic redesign . This paper was written by Chris Jay as a consultant to Exemplar Logi c, a California based supplier of synthesis tools to FPGA, PLD and ASI C manufacturers. The design example of a FIFO SRAM controller was comp leted and synthesized into a Xilinx FPGA device. Resulting simulation in the target technology confirmed functionality of the specific appli cation.