Author Archives: Michal Necasek

Kids these days…

Posted on September 8, 2013 by Michal Necasek

By sheer accident I stumbled on this document. In summary, it’s about a bunch of school kids working on a computer history preservation project and trying to archive a big box of floppies from George Alistair Sanger, a video game … Continue reading →

Posted in DOS, Floppies | 22 Comments

The XDF Diskette Format

Posted on August 30, 2013 by Michal Necasek

In 1994, IBM started shipping software with support for XDF, or eXtended Density Format, first in OS/2 Warp and a few months later in PC DOS 7.0. Some of IBM’s software packages were also distributed on XDF diskettes. XDF allowed … Continue reading →

Posted in Floppies, IBM | 24 Comments

Why Won’t IBM’s MSPS201.SYS Load?

Posted on August 23, 2013 by Michal Necasek

Recently a minor mystery resurfaced. When IBM’s OS/2 1.2 SE is installed on any “normal” system (either physical or virtual) and the PS/2 mouse driver is installed (the typical choice), the mouse won’t work: The MSPS201.SYS driver is intended for … Continue reading →

Posted in IBM, OS/2 | 8 Comments

Detecting Floppy Drives and Media

Posted on August 14, 2013 by Michal Necasek

Detecting floppy drive types and installed media is a far trickier topic than it should have been. In the ideal world, software could determine how many floppy drives are attached, what their capabilities are, and what media is installed in … Continue reading →

Posted in Floppies, IBM, PC hardware | 18 Comments

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 | 37 Comments