bit-accurate simulation model

Concept

In the cited microprocessor context, a bit-accurate simulation model is a software functional model, equivalently an Instruction Set Simulator (ISS), that represents the programmer-visible architectural behavior of a machine rather than its detailed microarchitecture. It models instruction execution as transitions between stable architectural states and is used as a reference against HDL models in pseudo-random hardware verification, with the caveat that shared bugs in both models may go undetected.

First seen 5/31/2026

Last seen 6/5/2026

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bit-accurate simulation model

A bit-accurate simulation model is described in the source as a software simulation model used as a functional model; in the context of microprocessors, the paper says this is equivalently an Instruction Set Simulator (ISS). The source characterizes such software models as providing a good estimate of hardware behavior while being easier to write and much faster to run, with 2 to 3 orders of magnitude of speedup cited as a common requirement.

Programmer-visible machine view

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Code-based Test Generation for Validation of Functional Processor Descriptions ← uses 100% 1e

The paper focuses on bit-accurate simulation models for hardware verification.

LINKED ENTITIES

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Instruction Set Simulator also_known_as The source states that bit-accurate software simulation models are referred to as functional models or, in the context of microprocessors, equivalently to ISS Instruction Set Simulators.

Hardware Verification used_for A dedicated section in the source describes the use of the simulation model for hardware verification by comparing behavior on generated assembler sequences.

Architectural State models The source defines the functional view in terms of architectural state, specifically the contents of registers and memories, and instruction execution as transitions between stable architectural states.

CITATIONS

7 sources

7 citations — click to expand

[1] In the cited microprocessor context, bit-accurate software simulation models are treated as functional models and are referred to equivalently as ISS Instruction Set Simulators. { Fabrice.Baray,Henri.Michel} ral

[2] The source says these software models should provide a good estimate of hardware behavior, be easier to write, and run much faster, with 2 to 3 orders of magnitude speedup described as a common requirement. { Fabrice.Baray,Henri.Michel} ral

[3] The model represents the programmer-visible machine view in terms of architectural state such as register and memory contents. { Fabrice.Baray,Henri.Michel} ral

[4] In this view, instruction execution is modeled as a change from one stable architectural state to another stable architectural state. { Fabrice.Baray,Henri.Michel} ral

[5] The functional model omits microarchitectural aspects such as pipelines, branch prediction, and multiple execution units, and has no notion of parallel execution or multi-cycle instruction execution. { Fabrice.Baray,Henri.Michel} ral

[6] For hardware verification, the source describes generating small assembler sequences and checking that they exhibit the same behavior on the HDL model and on the functional simulator. { Fabrice.Baray,Henri.Michel} ral

[7] The same verification method has a stated limitation: if both the HDL model and the ISS exhibit the same bug, comparison between them does not reveal the problem. { Fabrice.Baray,Henri.Michel} ral