Taken from the developer of RChipSim's website...
Reads51 is an integrated applications software
development system, which runs on an IBM PC or
compatible host. Reads51 contains a C compiler,
relative assembler, linker/locator, editor, chip
simulator, assembly language debugger, and
host-to-board communications in a user-friendly,
It seems like you simulate circuits and programs inside the environment.
I dont know of any applications for linux that will do the same, since the application is made for a certain chip.
You are probebly going to have to emulate this app.