Category Archives: 486

Learn Something Old Every Day, Part VIII: RTFM

Posted on August 22, 2023 by Michal Necasek

In my quest to understand the intricacies of x87 behavior and especially floating-point exceptions, I pulled out my trusty old Alaris Cougar board. The system board had a 100 MHz Intel OverDrive 486 DX4 plugged in and worked quite well. … Continue reading →

Posted in 486, Documentation, Intel, PC hardware, x87 | 9 Comments

Nobody Expects…

Posted on April 14, 2021 by Michal Necasek

…the Spanish Inquisition! Well, that too, but also nobody expects that a bland, run-of-the mill Novell NE2000 NDIS driver would crash/hang just because it runs on 486 or later CPUs. I wanted to try the “basic” DOS redirector shipped with … Continue reading →

Posted in 486, Bugs, Intel, Microsoft | 7 Comments

More Data on CF to IDE to SCSI

Posted on March 6, 2017 by Michal Necasek

To get a better picture of the performance of the CF to IDE to SCSI solution, I moved the Adaptec 1542C into one of my favorite boards, the Alaris Cougar with a classic Intel 486 DX2 OverDrive CPU. For a … Continue reading →

Posted in 486, CompactFlash, IDE, Storage | 16 Comments

Intel OverDrive Part II: Pentium OverDrive

Posted on June 30, 2016 by Michal Necasek

The Pentium OverDrive is notable for supporting three physically different sockets (that’s not counting the Pentium II OverDrive). The Pentium OverDrive product was sold in variants suitable for Socket 2/3 (486 systems), Socket 4 (early Pentium systems), and Socket 5/7 … Continue reading →

Posted in 486, Intel, PC history, Pentium | 21 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 | 37 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 | 22 Comments

Intel 420TX Chipset

Posted on May 9, 2015 by Michal Necasek

The OS/2 Museum recently obtained a somewhat unusual board: A 1993 vintage 486 PCI/ISA board equipped with the Intel 420TX chipset. The 420TX chipset, codenamed Saturn, was probably Intel’s first PCI chipset available to customers. It was probably first sold … Continue reading →

Posted in 486, Intel, PC hardware, PCI | 42 Comments

What’s in a Name?

Posted on March 7, 2014 by Michal Necasek

The following four processors are much more similar than one might think: 486 aficionados will recognize the processors made by IBM, ST Microelectronics, and Texas Instruments to be essentially one and the same model—Cyrix 486DX.

Posted in 486, Cyrix | 14 Comments

Soyo SY-4SAW2 Notes

Posted on February 26, 2014 by Michal Necasek

Following is a list of notes describing several less-than-obvious features and characteristics of the Soyo SY-4SAW2 486 VIP motherboard. This is a latter-day 486 board based on the SiS 496/497 chipset, notable for PS/2 mouse support and the ability to … Continue reading →

Posted in 486, PC hardware | 8 Comments