Author Archives: Michal Necasek

Detecting an Empty Drive… Or Not

Posted on August 3, 2013 by Michal Necasek

Detecting an empty drive with a NEC uPD765A or compatible FDC is theoretically easy using the ‘drive ready’ signal. In practice, the drive ready mechanism is completely unusable on IBM PCs and compatibles due to the way the FDC is … Continue reading →

Posted in OS/2, PC hardware | 16 Comments

OS/2 2.0 LA and “Large” IDE Disks

Posted on July 26, 2013 by Michal Necasek

Attempting to boot OS/2 2.0 LA (Limited Availability) on many systems built in the last 20 years often results in the following crash: The trap screen claims there was an exception (Trap 0 or division overflow) in device driver A:, … Continue reading →

Posted in IDE, OS/2 | 4 Comments

Twenty Years Ago Today…

Posted on July 24, 2013 by Michal Necasek

On July 24th 1993, Microsoft finalized the first release of Windows NT, labeled version 3.1 “to avoid confusion”. This was a big day for Microsoft, although the practical impact on the computer industry was not particularly big, at least not … Continue reading →

Posted in Microsoft, NT | 6 Comments

UNIX Alphabet Soup

Posted on July 21, 2013 by Michal Necasek

When reading historical UNIX documentation or source code, one is likely to come across various terms and acronyms that are now more or less completely forgotten, even among current developers of UNIX or UNIX-like systems. These acronyms might be the … Continue reading →

Posted in UNIX | 3 Comments

Preserving Floppies

Posted on July 14, 2013 by Michal Necasek

For many years, software was delivered predominantly on floppies. This was true especially in the world of PCs where by definition (almost) every system contained at least one floppy drive and prior to the mid-1990s and mass arrival of CD-ROMs, … Continue reading →

Posted in PC history, Virtualization | 25 Comments

ATI mach8/mach32/early mach64 Documentation?

Posted on June 26, 2013 by Michal Necasek

It’s a long shot, but I’m looking for programming documentation for ATI’s mach8/mach32 and early mach64 chips (prior to 1996 or so). The earlier documents may have only existed in paper form. These used to be available from ATI but … Continue reading →

Posted in ATi, Documentation | 44 Comments

BSD Buglets

Posted on June 15, 2013 by Michal Necasek

Last week I ran into two wholly unrelated problems while researching the history of BSD-derived Unix systems on PCs. Both are classics in their category and merit a closer look. Y2K Strikes Again The first issue is a very typical … Continue reading →

Posted in BSD, UNIX, x86 | 11 Comments

PC DOS Retro

Posted on June 12, 2013 by Michal Necasek

There’s a new DOS history and reference information website called simply “PC DOS Retro Page”. The site includes several reference pages (DOS commands, drivers, functions, internal structures) as well as a very extensive timeline of DOS releases. Vernon Brooks, the … Continue reading →

Posted in DOS | 21 Comments

If you ENTER, you might not LEAVE

Posted on June 7, 2013 by Michal Necasek

I’ve recently spent some time debugging curious hangs/aborts in two more or less exotic operating systems, Plan 9 and QNX 4.25. Both turned to be caused by the same innocuous-looking BIOS change, even though the circumstances were somewhat different and … Continue reading →

Posted in Intel, x86 | 9 Comments

Why I Don’t Want a Laptop with a Glued-In Battery

Posted on May 30, 2013 by Michal Necasek

Here’s why: Not much to add really… in this case, the laptop wasn’t damaged because the battery simply forced its way out of the shell. If it had been glued in, it would have destroyed the case and quite possibly … Continue reading →

Posted in Apple | 6 Comments