chicken bit

From chicken, in the sense of chicken out.

chicken bit (plural chicken bits)

1. (electronics) A bit on a chip that can be used to disable one of the features of the chip if it proves faulty or negatively impacts performance.
   • 2010, Ilya Wagner & Valeria Bertacco, Post-Silicon and Runtime Verification for Modern Processors, →ISBN, page 165:

     As an example, modules such as branch predictors and speculative execution units can be turned off with a variant of the “chicken bits”, control bits common to many design developments to control the activation of specific features.

   • 2015, Erik Seligman, ‎Tom Schubert, ‎M V Achutha & Kiran Kumar, Formal Verification, →ISBN, page 237:

     Validation of a chicken bit can be challenging, because disabling a feature is often as intrusive in the code as the feature itself.

   • 2015, Vincent Zimmer, ‎Jiming Sun, & ‎Marc Jones, Embedded Firmware Solutions: Development Best Practices, →ISBN, page 6:

     As a matter of fact, most of these chicken bits will never be documented, and a small portion of the chicken bits will be documented only when they are needed to work around a chip problem.

2. Used other than with a figurative or idiomatic meaning: see chicken,‎ bit.