Category Archives: Bugs

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

PCI Corner Case

Posted on March 20, 2017 by Michal Necasek

Last weekend I had the pleasure of debugging a curious case of older PCI configuration code (circa 2005) failing on newer (post-2010) hardware. The code was well tested on many 1990s and 2000s PCs (and some non-PCs) with PCI/AGP/PCIe and never … Continue reading →

Posted in Bugs, Intel, PCI | 11 Comments

Resetting Disks Is Hard

Posted on February 26, 2017 by Michal Necasek

After digging through BIOS listings and disassembling the Adaptec 1542C BIOS as well as the PC DOS 2000 boot sector, it’s clear why the floppy-less SCSI boot does not work on my test system. It’s because disk reset done by the boot … Continue reading →

Posted in BIOS, Bugs, SCSI | 22 Comments

Windows 3.1 Standard Mode Crash with APM

Posted on July 22, 2016 by Michal Necasek

On some systems, Windows 3.1 and 3.11 in Standard mode crashes when it is configured to use APM, i.e. POWER.DRV is loaded. The crash only happens in Standard mode, not the typical default 386 Enhanced mode. Since POWER.DRV is involved … Continue reading →

Posted in Bugs, Windows | 16 Comments

Solaris 7 Boot Panic

Posted on April 23, 2016 by Michal Necasek

On some systems, it has been observed that Solaris 7 panics during boot from installation media and reboots the system. At least Solaris 7 U1 (3/99) and U4 (11/99) are affected. Only “fast” systems (definitely including Sandy Bridge 3+ GHz … Continue reading →

Posted in Bugs, Debugging, Solaris | 6 Comments

Something Happened

Posted on July 30, 2015 by Michal Necasek

My first experience with the Windows 10 media creation tool was, in a word, terrible. After 20 minutes or so of downloading, the tool told me that “Something happened” and the only option was to exit. That’s probably what passes … Continue reading →

Posted in Bugs, Microsoft | 17 Comments

Solaris 2.6, 7, and 8 Crashes on Pentium 4 and Later

Posted on February 27, 2015 by Michal Necasek

A blog reader recently pointed to an interesting problem which affects older Solaris releases on certain systems. The symptoms (crash/reboot) may at first glance look like the previously described problem which affected Solaris 2.5.1 and 2.6, but both the cause and … Continue reading →

Posted in Bugs, Debugging, Intel, Solaris | 2 Comments

Demented Board

Posted on January 31, 2015 by Michal Necasek

Last week I encountered a problem that I have never seen before with a recently acquired Socket 7 motherboard. The board was a Gigabyte GA-586HX (Rev. 1.58), a relatively uninteresting older Socket 7 board based on the well-regarded Intel 430HX … Continue reading →

Posted in Bugs, PC hardware | 14 Comments

Windows 8.1 Startup Bugcheck 0xC4

Posted on November 30, 2014 by Michal Necasek

On some systems, both physical and virtual, 64-bit Windows 8.1 as well as Server 2012 R2 consistently crashes with error code (bug check) 0xC4; 64-bit Windows 8 may run on these same systems without trouble. On physical systems, the BSOD … Continue reading →

Posted in Bugs, Microsoft, NT, VirtualBox | 15 Comments

386 Memory Managers and DMA

Posted on September 12, 2014 by Michal Necasek

A while ago I ran into an odd problem: A virtual machine running QEMM 9.0 (aka QEMM 97) would crash more or less every time it tried to read something from a floppy. No such problem was observable in any … Continue reading →

Posted in 386, Bugs, DOS, PC hardware | 7 Comments