SSC-DASH (Server Side C-DASH) has been developed as a web-based HW/SW codesign tool for designing processors. SSC-DASH obtains a processor definition file via web browser and generates a HW (synthesizable Verilog-HDL description) and SWDE (Software Development Environment) for the generated processor. The SWDE includes ISS (Instruction SetSimulator), assembler, disassembler and compiler. For the verification of the defined processor, processor developers have to download the generated SWDE, every time, even where changes are small. To improve the usability of this system a web-based interface for the generated SWDE is implemented using Ajax. Using Ajax, download of the SWDE becomes unnecessary and makes it possible to verify the processor on the server quickly and easily. This greatly improves the usability of the SWDE. In this paper, we describe implementation of web-based ISS using Ajax.