Analyzing The FScale Instruction In Intel’s 8087 FPU

Ken Shirriff's ongoing reverse-engineering of the Intel 8087 FPU's microcode reveals that the FSCALE instruction, which appears to be a simple powers-of-two scaling operation, actually requires over 140 micro-instructions and three levels of subroutine calls to handle all edge cases. The die shot analysis illustrates the substantial hardware dedicated to this single x87 instruction, highlighting how the 8087's rigorous handling of error conditions and stack management influenced the later IEEE 754 floating point standard.

Source: https://hackaday.com/2026/09/13/analyzing-the-fscale-instruction-in-intels-8087-fpu. 8 Sync News only summarizes and links out; content copyright belongs to the authors and original sources.