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Hamarsoft 86BUGS list

The 86BUGS list is the world standard reference for bugs and undocumented instructions in the Intel 80x86 family of processors.


Written and compiled by Harald Feldmann and acknowledged by many leading programmers, the list is now in its fifth year. For your convenience the list is available in ZIP, ACE and HAP formats.

86BUGS list in ZIP format.

86BUGS list in ACE format.

There is also a version available with test software to see if your CPU is affected by some of the bugs mentioned in the list.

86BUGS and software in ZIP format

86BUGS and software in ACE format

Please send feedback on the list to

Out of common courtesy, please also notify us if you mention the list in a publication or program.