Comments on Some Of The Papers

• EDSAC Debug introduces several things including: multiple strategy execution that switches between simulation for tracing and direct execution for speed; and displaced execution that simulates an instruction by copying it from its original location. EDSAC Debug also describes a fairly modern debugger; the paper is from 1951!
• ST-80 introduces the idea of dynamically cross-compiling groups of instructions from the simulated target machine to run directly on the host machine. Mimic extends this idea to work on a real (non-virtual) instruction set and shows how several important optimizations can be performed using runtime information.
• g88 shows how a simple and portable interpreter can simulate a processor with modest slowdown.
• g88 also introduces fast sophisticated address translation used to implement multiple-domain and system-mode simulation. One of the SimICS papers shows a construction for optimizing and abstracting address translation. SimOS shows how to do use the host's MMU to perform address translation even faster.
• CRISP introduces the idea of dynamic compilation of machine instructions to microcode.
• Kx10 shows how to simulate a 36-bit DEC-10 on machines that have 32-bit words.
• Mime introduces the notion of checkpointing and rollback of simulator state, used to simulate and trace the effects of e.g. speculative execution.
• OM describes tool-building tools for tracing.
• Talisman introduces fast approximate timing simulation that can estimate program running time with high accuracy (within a few percent; turning off e.g. dynamic RAM refresh simulation reduces accuracy dramatically), while adding only several tens of instructions to the cost of each simulated instruction.
• Mshade (a component of SimOS) and T2 use dynamic cross-compilationr to implement system mode code. There is often less benefit over interpretation because system code tends to have checking overheads that narrows the gap between translation and interpretation.
• WWT applies the idea of exploiting hardware features to use distributed shared virtual memory for user-mode multiprocessor simulation and tracing. Tapeworm II extends the idea to use general memory reference exceptions for general user and system-mode tracing.