On Wed, 05 Nov 2003 00:23:43 -0800, Sandeep Chikkerur wrote:

> Hi,
>
> What is the difference between a
>
> - CYCLE ACCURATE SIMULATOR &
> - INSTRUCTION ACCURATE SIMUALTOR.
>
> (e.g. ZSP400, ZSP500 Simulators have both the options)
>
> Which is advantageous ?

The terms don't have a universal definition AFIK, but to guess, I'd say:

A cycle-accurate simulator will both run your program *and* tell you how
many cycles it took to execute, perhaps taking things like the number of
configured wait states for external memory accesses and so-on into account.

An instruction-accurate simulator probably just runs your program as fast
as it can: the computations will be according to the instruction set, but
it won't tell you how long each instruction or your whole program will
take. This simulation might run significantly faster than the
cycle-accurate one, perhaps even using a JIT compiler or interpreter, in
the way of a Java VM.

For some things, particularly real-time code, and for detailed
optimization, you need to know how many cycles something will take. At
other times, you just want to know whether or not your code, running in
batch mode (not real-time), is correct or not.

I've often wanted the latter, but have not seen it offered for a DSP
before. If it's what I'm assuming, then that's quite possibly a useful
advance on the part of LSI/ZSP.

--
Andrew