Category Archives: AMD

Undefined Isn’t Unpredictable

Posted on November 7, 2022 by Michal Necasek

The other day I discovered that 32-bit FreeBSD 11.2 has strange trouble running in an emulated environment. Utilities like ping or top would just hang when trying to print floating-point numbers through printf(). The dtoa() library routine was getting stuck … Continue reading →

Posted in AMD, Development, Documentation, Intel | 22 Comments

Those Win9x Crashes on Fast Machines…

Posted on June 2, 2020 by Michal Necasek

It is well known that Win9x variants prior to Windows 98 have a tendency to crash on fast CPUs. The definition of “fast” is of course fuzzy but the problems were known to occur on AMD K6-2 processors running at … Continue reading →

Posted in AMD, Bugs, Intel, Microsoft | 24 Comments

More on NX Insanity

Posted on November 29, 2019 by Michal Necasek

This article was supposed to be published about two years ago but got forgotten and ignored until now. It’s not the only such article. Perhaps it will start a new “better published late than never” series. After looking more closely … Continue reading →

Posted in AMD, Bugs, Intel, Microsoft | 13 Comments

It’s Zen Time

Posted on October 14, 2019 by Michal Necasek

Back in 2003, it was Hammer Time for the PC industry. My own home PCs missed the wave because I had just bought a 3.2 GHz Northwood Pentium 4, which was replaced in 2006 by a Core 2 E6600, a … Continue reading →

Posted in AMD, PC hardware, Ryzen | 8 Comments

My Second AMD

Posted on December 13, 2018 by Michal Necasek

A few weeks ago I became a happy owner of a ThinkPad A485, the first ThinkPad (together with the E485 and related variants) to use an AMD CPU. History buffs will know that it’s far from the first ThinkPad with … Continue reading →

Posted in AMD, PC history, ThinkPad | 38 Comments

AMD64 APM Archive Online

Posted on December 29, 2017 by Michal Necasek

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 | 2 Comments

AMD64 Manual Vol. 3 Rev. 3.24 Anyone?

Posted on December 24, 2017 by Michal Necasek

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

Posted on June 11, 2017 by Michal Necasek

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 1.0.0.6, 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

Posted on May 12, 2017 by Michal Necasek

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

Posted on May 4, 2017 by Michal Necasek

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 | 39 Comments