Category Archives: AMD

AMD64 APM Archive Online

Thanks to Konstantin Belousov, the OS/2 Museum AMD64 APM (Architecture Programmer’s Manual) is now available online. Big thanks to blog readers who recently supplied several missing revisions of the documents. This is a nearly complete archive of all published AMD64 … Continue reading

Posted in AMD, AMD64, Documentation | Leave a comment

AMD64 Manual Vol. 3 Rev. 3.24 Anyone?

AMD tricked me. After not updating anything for months, they updated the AMD64 documentation and not only that, they updated Volume 3 (instruction reference) twice within a few weeks. First to revision 3.24 in November, then 3.25 in December. I … Continue reading

Posted in AMD, Documentation | 3 Comments

VME Fixed on AMD Ryzen

As expected, AMD fixed the problem with VME that affected Ryzen processors. The fix is shipped in the form of a microcode patch as part of AGESA, currently being rolled out by OEMs as part of a BIOS update. … Continue reading

Posted in AMD, Bugs | 17 Comments

VME Broken on AMD Ryzen

That’s VME as in Virtual-8086 Mode Enhancements, introduced in the Intel Pentium Processor, and initially documented in the infamous NDA-only Appendix H. Almost immediately since the Ryzen CPUs became available in March 2017, there have been various complaints about problems … Continue reading

Posted in AMD, Bugs | 36 Comments

SGDT/SIDT Fiction and Reality

PSA: Actual hardware behavior takes precedence over vendor documentation. Or, as they say… trust but verify. A reader recently complained how Intel and AMD do not implement the SGDT and SIDT instructions the same way. AMD documentation states that these … Continue reading

Posted in 286, 386, AMD, Documentation, Intel | 38 Comments

How the PC Industry Screws Things Up

I was recently involved in investigating a problem that turns out to be a complete SNAFU which nicely illustrates the chaos that is the PC platform. It’s about the NX/XD bit. Let’s start with a bit of history. It turns … Continue reading

Posted in AMD, Intel, Microsoft | 34 Comments