Author Archives: Michal Necasek

Before OS/2 Was OS/2

Posted on February 5, 2016 by Michal Necasek

After almost 30 years, several disks with ancient builds of OS/2 surfaced. In this context, “ancient” means older than the May 1987 release of the first MS OS/2 SDK. In fact these disks are so old that the one thing … Continue reading →

Posted in IBM, Microsoft, OS/2, PC history, Undocumented | 55 Comments

More CPUs in NT 3.x Workstation

Posted on January 22, 2016 by Michal Necasek

The default processor limits of Windows NT 3.x are surprisingly difficult to establish. Quite possibly because although SMP was a big selling point of NT, in reality only a tiny fraction of PCs in the mid-1990s supported SMP, and of those, … Continue reading →

Posted in NT, Software Hacks | 3 Comments

Windows NT 3.1 (and OS/2) Memory Detection

Posted on January 15, 2016 by Michal Necasek

It is common knowledge that Windows NT 3.1 only recognizes up to 64 MB RAM, unlike NT 3.5 and later versions. This statement can be found in various places, including this blog. The limitation was empirically determined by installing NT … Continue reading →

Posted in BIOS, NT | 39 Comments

NT 3.1 SMP

Posted on January 12, 2016 by Michal Necasek

Generic x86 multiprocessing, Summer 1994 edition. There’s not much to say: Yep, that’s NT 3.1 running in a VM, and it sees two processors. Remember, you saw it here first!

Posted in Intel, NT, SMP | 70 Comments

386 LOADALL

Posted on January 7, 2016 by Michal Necasek

I recently came across hints suggesting that in the 1987 timeframe, Microsoft contemplated the use of the 386 LOADALL instruction in OS/2. As far as I know, no released version of OS/2 (including the SDK betas) utilized the 386 LOADALL. … Continue reading →

Posted in 386, Undocumented | 32 Comments

Missing Intel SDM Documents

Posted on December 30, 2015 by Michal Necasek

I’ve been trying to complete my archive of Intel SDM documents circa 2000 and later. I have most of the editions archived but a few are missing. Readers of this blog could have something stashed away too, so perhaps someone … Continue reading →

Posted in Documentation, Intel | 11 Comments

Lies, Damn Lies, and Wikipedia

Posted on December 26, 2015 by Michal Necasek

While researching the history of 486s for a previous article, I came across a fascinating Wikipedia entry and its associated talk page. It’s a nice showcase of inmates running the asylum, and a reminder that Wikipedia can’t be considered an authoritative … Continue reading →

Posted in 486, Intel, PC history | 38 Comments

Intel OverDrive Part I: 486 OverDrive

Posted on December 13, 2015 by Michal Necasek

Intel had a long history of offering retail processor upgrades for PCs. The last and by far the best known of those were the Intel OverDrive processors. But let’s start with the earlier history. In 1987, Intel released the Inboard 386/AT, … Continue reading →

Posted in 486, Intel, PC history | 6 Comments

Intel 486 Errata?

Posted on December 6, 2015 by Michal Necasek

There don’t seem to be any specification updates or errata lists for any Intel 486 CPU anywhere. It’s odd because there are specification updates for 386s (and of course Pentiums) from Intel, and because the embedded 486s continued to be … Continue reading →

Posted in 486, Intel, PC history | 23 Comments

MS C 4.0 Documentation Added

Posted on November 27, 2015 by Michal Necasek

Another library expansion. This time it’s Microsoft C 4.0 documentation (1986)—because it’s not available online, is not easy to find offline, and because Jeff asked for it. MS C 4.0 was an early Microsoft compiler, implementing first glimpses of the not-yet finalized … Continue reading →

Posted in C, Documentation, DOS, Microsoft | 7 Comments