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STIMSMITH

Comparator (RTL vs ISS)

Concept

A Comparator in RTL-versus-ISS co-simulation is the component that detects functional mismatches between an RTL core and an ISS reference model. In the cited setup, it compares register-value changes from both sides, aligns them by change position to tolerate different timing behavior, and terminates simulation when a difference is found.

First seen 5/30/2026
Last seen 5/30/2026
Evidence 2 chunks
Wiki v1

WIKI

Overview

In the described cross-level processor verification flow, the Comparator is the component responsible for finding functional differences between the RTL-Core and the ISS.

How it works

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NEIGHBORHOOD

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RELATIONSHIPS

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The Comparator is used to find functional differences between RTL-Core and ISS.
Instruction Set Simulator (ISS) uses → 90% 1e
The Comparator compares results between the ISS and the RTL core.

CITATIONS

4 sources
4 citations — click to collapse
[1] The Comparator's purpose is to find functional differences between the RTL-Core and the ISS. Cross-Level Processor Verification via Endless Randomized Instruction Stream Generation with Coverage-guided Aging
[2] The Comparator compares register values of the ISS and RTL-Core; because the two cores do not have the same timing behavior, it logs value changes and compares the two change streams at the same position. Cross-Level Processor Verification via Endless Randomized Instruction Stream Generation with Coverage-guided Aging
[4] The broader verification environment leverages an ISS as a reference model in a tight co-simulation setting. Cross-Level Processor Verification via Endless Randomized Instruction Stream Generation with Coverage-guided Aging