Category Archives: PC hardware

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

IBM Blue Lightning: World’s Fastest 386?

Posted on August 22, 2014 by Michal Necasek

One of the OS/2 Museum’s vintage boards is a genuine Made in U.S.A. Alaris Cougar. These boards were produced by IBM for Alaris and are a bit unusual: There’s a small IBM DLC3 processor in plastic package soldered on board, … Continue reading →

Posted in 386, IBM, Intel, PC hardware, PC history | 62 Comments

S3 Fraternal Twins

Posted on June 20, 2014 by Michal Necasek

Sometimes identifying old hardware is a bit tricky. Consider these two graphics cards: The PCB is the same, the BIOS chips look the same, the DAC is slightly different but an 80 MHz part in both cases, memory is the … Continue reading →

Posted in Graphics, PC hardware, S3 | 5 Comments

Floppy Capacity Math

Posted on June 8, 2014 by Michal Necasek

After more or less accidentally coming across a BBS listing of various high-capacity floppy formatting programs, I began wondering: How much data can really be stored on a diskette in a PC floppy drive? And what’s the relationship between formatted … Continue reading →

Posted in Floppies, PC hardware | 38 Comments

The ISA OSC Mystery

Posted on April 3, 2014 by Michal Necasek

About twenty years ago I ended up with a spare ISA graphics card from an upgraded computer. It was a SVGA card based on the Cirrus Logic CL-GD5422 chip, equipped with 1 MB video memory. This was a very cheap … Continue reading →

Posted in Cirrus Logic, Graphics, PC hardware | 15 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

Untested Error Paths

Posted on February 20, 2014 by Michal Necasek

About a week ago I revived an old Sony VAIO laptop (model PCG-R505TS) that hadn’t been used for a few years. It had lost CMOS contents so I had to re-enter the date and adjust a few BIOS settings. The … Continue reading →

Posted in PC hardware, Windows | 3 Comments

Soyo 4SAW2: Why So Slow?

Posted on February 15, 2014 by Michal Necasek

Continuing to go through my junk pile, I unearthed a Soyo SY-4SAW2 motherboard. This is a late 1995 vintage 486 ISA/VLB/PCI motherboard with a SiS 85C496/497 chipset. It’s a classic Baby AT board with an AT keyboard connector, although it … Continue reading →

Posted in PC hardware | 21 Comments

Butterfly Conservation

Posted on February 8, 2014 by Michal Necasek

The OS/2 Museum recently acquired one of the famous IBM 701 ThinkPads, commonly nicknamed “Butterfly” thanks to the fold-out keyboard. Unfortunately, the unit suffered a fate common to many old ThinkPads—battery leakage. The unit would power on, but it had … Continue reading →

Posted in PC hardware, ThinkPad | 3 Comments

Have You Ever Used One of These?

Posted on January 31, 2014 by Michal Necasek

Still on the theme of unusual hardware… in my junk pile there’s one of these rather special little parts: As the label on the PCB says, this is a 486 pod for a Periscope IV debugger. The Periscope Company of … Continue reading →

Posted in Debugging, PC hardware | 35 Comments