How to make sure your program doesn’t run on Windows 95

Posted on January 24, 2012 by Michal Necasek

For Christmas, I bought myself the book The Old New Thing by Raymond Chen, a long-time Microsoft programmer. The purchase was spurred by discovering, through Google Books, an excerpt of a riveting description of how various software titles abused the DPMI specification (and often common sense, too) in ways that made it difficult to run such software under Windows 95.

When I was nearly done reading my copy of the book, I realized that the protected mode programming treatise wasn’t there. Back to Google, I checked that my memory wasn’t deceiving me—yep, still there on Google Books. But for some odd reason, there are no page numbers in the excerpts of The Old New Thing that show up on Google Books, so I could not cross check with my printed copy. After a few more searches, I concluded that there are two appendixes which were probably never printed and only exist in electronic form. Continue reading →

Posted in PC history | 10 Comments

DOS/V graphics text modes and scrolling

Posted on January 22, 2012 by Michal Necasek

I recently ran into an interesting difference in the way various DOS/V versions manage VGA memory. DOS/V of course refers to the Japanese versions of DOS which are capable of running on standard “Western” hardware.

Microsoft has a very long history of supporting the Far East (how they used to be called) markets, especially Japanese and Korean, going back to the early 1980s. At that time, standard PC hardware was simply not capable of displaying Kanji ideographs; MDA had no user-definable fonts, and CGA had woefully low resolution. Systems tailored to the Japanese market used custom hardware, more or less incompatible with IBM PCs.

Once the VGA appeared, the technology was capable of emulating text modes using a relatively high resolution (for the time) graphics mode. MS-DOS/V versions 5.0 and 6.2 (released in March and December 1993, respectively; further referred to as DOS/V) both used a 640×475 graphics mode, slightly unusual but logical. The character cell was 19 pixels high and 8 or 16 pixels wide (Kanji ideographs, usually encoded as two bytes, were also displayed twice as wide as standard ASCII characters). To display an 80×25 text mode using a 19 by 8 pixel character cell, a 640×475 resolution is required. That’s not quite the same as the standard 640×480 VGA resolution, but it’s the closest lower resolution usable for relatively detailed glyphs and 80×25 grid. Continue reading →

Posted in DOS, VGA | Leave a comment

Jumpy PS/2 mouse in Enhanced mode Windows 3.x

Posted on December 21, 2011 by Michal Necasek

There’s an interesting (and quite annoying) bug specific to Windows 3.x running in 386 enhanced mode (also known as Windows/386) and using a PS/2 mouse. In some situations, the mouse may jump to the top or the bottom of the screen, especially when the system is somewhat unresponsive. The cause of the jumpiness turns out to be a subtle bug in VKD (Virtual Keyboard Device), a virtual device (VxD) which is part of Windows/386.

The way PS/2 mouse input is handled in Windows/386 is extraordinarily complex. The mouse driver (MOUSE.DRV) simply uses the BIOS INT 15h, sub-function C2h interface to register a mouse callback routine. The BIOS uses IRQ 12 and I/O ports 60h/64h to read data from the mouse. However, the VKD VxD inserts a whole new layer between the BIOS and the mouse hardware. Continue reading →

Posted in Windows | 9 Comments

Simple Windows NT video miniport for VirtualBox

Posted on December 18, 2011 by Michal Necasek

A few months ago, I developed a trivial video miniport for use in Windows NT virtual machines. The primary goal was to improve display speed and get past the 800×600, 16 color display mode which is the maximum Windows NT (up to an including Windows 2000) can handle out of the box on “modern” hardware. The miniport is designed to work with the synthetic SVGA “hardware” emulated by VirtualBox.

A secondary objective was to write the miniport in such a way that as many Windows NT versions could be supported with a single binary. That objective was fulfilled beyond expectations; the driver binary works with every x86 version of NT from the initial July 1993 release of Windows NT 3.1 up to and including Windows 7 released in October 2009. Windows 8 appears to drop the video miniport interface and thus cannot be supported. Continue reading →

Posted in NT, VirtualBox | 26 Comments

Microsoft OS/2 1.0 user documentation

Posted on December 17, 2011 by Michal Necasek

In late 1987, Microsoft shipped a set of OS/2 1.0 user documentation as part of the OS/2 SDK. The set included the Setup Guide, Beginning User’s Guide (a tutorial style document), and User’s Reference. The manuals were similar in style to DOS documentation from that era and likely produced on XENIX using the standard UNIX document production tools (i.e. troff and related utilities).

The manuals shipped by Microsoft were not entirely finished. Some of the more involved explanations were incomplete, screenshots were missing, and a few illustrations weren’t provided. That said, end users were not expected to see those manuals. Instead, OEMs would adapt (or completely rewrite) the OS/2 documentation provided by Microsoft. Continue reading →

Posted in Documentation, OS/2 | 3 Comments

Converting NT DDK/SDK PostScript documents to PDF

Posted on November 19, 2011 by Michal Necasek

Pre-releases of Microsoft’s NT development tools, as well as the final NT 3.1 SDK and DDK, shipped with a full set of printable documentation in PostScript format. The PostScript book-style document were rather more pleasing to the eye than the WinHelp format, and especially for the explanatory “guide” material, some readers found them much nicer to work with.

But really, who wants thousands of pages of dead tree matter? The complete SDK/DDK documentation set ran to somewhere in the 10,000 pages range. It should be easy to convert the PostScript documents to PDFs and obtain a nice set of easily viewable and searchable documents. It should be easy… It’s anything but. Continue reading →

Posted in Documentation, NT | 5 Comments

OS/2 Warp installation pitfalls

Posted on November 9, 2011 by Michal Necasek

Recently I had an opportunity to install and update various versions of OS/2 (Warp 3 and later) in virtual machines. In the process I ran into several subtle and not so subtle issues which may be worth recording, complete with fixes/workarounds where applicable.

  • When installing OS/2 Warp Connect or Warp Server from CD, the installer may not correctly select the CD-ROM type. It must be manually set to “Unlisted IDE CD-ROM” (or probably any other IDE CD-ROM type), otherwise the networking install phase will fail with very cryptic errors. Continue reading →
Posted in OS/2, Virtualization | 14 Comments

Is it so hard to document things?

Posted on October 23, 2011 by Michal Necasek

A few weeks ago I spent a bit of time debugging a program which mysteriously failed under DOS 3.3, although it worked without any apparent problem on DOS 4.0 and later, and there was no indication that it required anything later than DOS 3.1 or so.

The problem turned out to be related to INT 21h, function 6300h, a curiously underdocumented DOS API. The call was first implemented in the Far East versions of MS-DOS 2.25 and returned a table of DBCS lead bytes. That is crucial information for software running on DBCS systems, required for correctly parsing pathnames etc. The RBIL also documents the call for Far East versions of DOS 3.2 and later. So what’s the problem? Continue reading →

Posted in DOS | 66 Comments

Running 1-2-3 R3 in a VM

Posted on October 22, 2011 by Michal Necasek

I recently tried to install the infamous Lotus 1-2-3 Release 3 from 1989 in a VM. The program disks included both DOS and OS/2 executables, and both were failing. The DOS version stopped with “Cannot initialize system driver” immediately after showing the splash screen, while the OS/2 version failed with the message “Error loading driver file LTSNW” at about the same point. Google was of no help whatsoever, as often happens with software that old. Continue reading →

Posted in DOS, PC history, VirtualBox | 3 Comments

Need for Speed SE video glitch

Posted on October 16, 2011 by Michal Necasek

When attempting to play the classic racing game Need for Speed SE in a virtualized environment (VirtualBox), I was dismayed to discover that all the in-game videos were completely garbled. Curiously, the introductory video played when the game is first launched looked fine, even though there was no reason to think it should be any different from the in-game videos.

Continue reading →

Posted in DOS, VirtualBox | 8 Comments