Author Archives: Michal Necasek

PC DOS 1.0, But Not Quite

Last week a most interesting image of a 160K disk arrived at the OS/2 Museum. The files on the disk image are rather old. When the disk boots up (not trivial, see below), the following message appears: Astute readers will … Continue reading

Posted in DOS, IBM, Microsoft, PC history, Pre-release | 43 Comments

How Many Gravis UltraSounds?

The question came up a while ago. Just how commercially unsuccessful was the Gravis UltraSound? There appears to be no public information about the sales volume of the UltraSound. But now, looking at a sample of 3 (three) classic GUS … Continue reading

Posted in PC history, Sound, UltraSound | 49 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 | 35 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 | 37 Comments

OS/2 2.0, Xmas ’91 Edition

After reviewing the OS/2 2.0 level 6.605 pre-release, another re-discovery is the “Limited Availability” (LA) level 6.177 from December 1991. This was the last OS/2 2.0 pre-release of 1991 and also the last one using the 6.1xx numbering; the next pre-release was … Continue reading

Posted in 386, IBM, OS/2, PC history | 15 Comments

CF/IDE/SCSI Benchmark Update

To see how the CF-to-IDE-to-SCSI solution really performs, I tried it in a slightly faster system. GA-586HX motherboard (Intel 430HX chipset), AMD K5-133 processor, and PCI SCSI HBAs. The first tested configuration was using a Tekram DC-390 HBA. Sysinfo showed 8.7 … Continue reading

Posted in CompactFlash, SCSI, Storage | 10 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 | 33 Comments

OS/2 2.0, Summer ’91 Edition

In a fascinating example of poor timing, disk images of OS/2 2.0 pre-release level 6.605 from July/September 1991 were missing for over 25 years, only to show up literally one day after after the 25th anniversary of the OS/2 2.0 release … Continue reading

Posted in 386, IBM, OS/2, PC history | 34 Comments

OS/2 2.0 at 25

Twenty-five years ago, on March 31st, 1992, IBM released OS/2 2.0, the first mass-market 32-bit PC operating system. The road to OS/2 2.0 was quite long and winding, and the OS was a proud member of the vaporware club (just like, … Continue reading

Posted in 386, IBM, Microsoft, OS/2 | 33 Comments

Something New Every Day…

Apparently in 1990, Intel still sold complete systems, and they were PC compatible at that point. And perhaps not surprisingly, Intel also OEMed MS OS/2 1.21: And there was this cute ASCII-art logo: There very little customization that Intel did, … Continue reading

Posted in Intel, OS/2 | 14 Comments