Category Archives: IBM

ThinkPad Fan

Posted on October 12, 2018 by Michal Necasek

I suppose I am one, but recently I had trouble with the other kind of a ThinkPad fan. An elderly ThinkPad 43p with a 2.13 GHz CPU (Dothan Pentium M with 2MB L2 cache) and a rather nice 1600×1200 IPS … Continue reading →

Posted in Hardware Hacks, IBM, ThinkPad | 4 Comments

A Sound Card Before Its Time

Posted on August 15, 2018 by Michal Necasek

A mysterious full-length sound card recently arrived at the OS/2 Museum. It was clearly manufactured by IBM in 1985, and sports a 20 MHz Texas Instrument TMS32010 DSP (the DSP is the large black DIP chip near the lower left … Continue reading →

Posted in IBM, PC history, Sound | 20 Comments

How Fast Is a PS/2 Keyboard?

Posted on July 23, 2018 by Michal Necasek

A few weeks ago, an interesting question cropped up: How fast is a PS/2 keyboard? That is to say, how quickly can it send scan codes (bytes) to the keyboard controller? One might also ask, does it really matter? Sure … Continue reading →

Posted in Borland, IBM, Keyboard, PC hardware | 14 Comments

OS/2 2.0, Spring ’91 Edition

Posted on July 10, 2018 by Michal Necasek

Thanks to a generous reader, a curiously nondescript box labeled “OS/2 32-Bit Pre-release” recently turned up at the OS/2 Museum. The box looks very much like retail IBM products from the early 1990s, but has no identifying description except for … Continue reading →

Posted in IBM, Microsoft, OS/2, PC history, Pre-release | 34 Comments

The A20-Gate Fallout

Posted on April 13, 2018 by Michal Necasek

A recent post explored the motivation (i.e. backwards compatibility) to implement the A20 gate in the IBM PC/AT. To recap, the problem IBM solved was the fact that 1MB address wrap-around was an inherent feature of the Intel 8086/8088 CPU, … Continue reading →

Posted in IBM, Microsoft, PC architecture, PC history | 93 Comments

The A20-Gate: It Wasn’t WordStar

Posted on March 16, 2018 by Michal Necasek

Although WordStar was long suspected to be the reason (or at least one of the major reasons) for implementing the A20 gate hardware on the PC/AT and all the associated problems later on, it is now all but certain that … Continue reading →

Posted in 286, IBM, Microsoft, PC history, WordStar | 37 Comments

Pascal Out Of Memory

Posted on February 23, 2018 by Michal Necasek

Suppose you want to run the original 1981 vintage IBM Pascal 1.0 (supplied by Microsoft) on a PC that is less than 30 years old. Upon execution, PAS1.EXE may well fail with the following error: Error: Compiler Out Of Memory … Continue reading →

Posted in Bugs, Corrections, IBM, Microsoft, PC history | 40 Comments

Audio Frequency Data Acquisition

Posted on August 23, 2017 by Michal Necasek

Readers of this blog may have noticed that besides OS/2 software, I have interested in PC sound cards. I thought I had a decent idea about the major milestones in PC sound history, but I had to perform a few … Continue reading →

Posted in IBM, MCA, PC hardware, PC history, PS/2, Sound, Sound Blaster | 17 Comments

PC DOS 1.0, But Not Quite

Posted on May 26, 2017 by Michal Necasek

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 | 47 Comments

OS/2 2.0, Xmas ’91 Edition

Posted on April 26, 2017 by Michal Necasek

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 | 16 Comments