Uploaded August 2024 | Updated September 2026, 2 weeks ago

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Most of you probably have heard of the FDIV bug the first Pentium processor suffered from, but have you heard of the F00F bug? The "foof" bug is an invalid x86 instruction that should have terminated in an exception; however, a combination of "LOCK" and comparing two CPU register values instead of a register with a memory location, causes CPUs based on the P5 microarchitecture to freeze. In this video, I will show you three methods how you can trigger the "F00F" bug on your retro system.

More details, source and executables: bitsundbolts.com/2024/08/14/intel-pentium-f00f-bug

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▬▬▬▬ *Timestamps* ▬▬▬▬▬▬▬▬▬▬▬▬▬▬
00:00 Intro
01:11 F00F in Windows 98 using C
08:19 F00F in DOS using a BAT file
10:32 F00F in DOS using copy con
12:37 Conclusion