Author Archives: Michal Necasek

Video trouble with Solaris 10 GA and U1

Posted on March 23, 2012 by Michal Necasek

The initial (GA) release of Solaris 10 from 2005 and the first update (Solaris 10 1/06) both have an interesting bug which causes trouble when installing those specific versions on VirtualBox and quite likely also on some mildly unusual hardware. The … Continue reading →

Posted in Solaris, VirtualBox | Leave a comment

Lotus 1-2-3 R3 copy protection

Posted on March 17, 2012 by Michal Necasek

Release 3 of Lotus 1-2-3 (1989) utilized a mild form of copy protection which relied partially on technology but primarily on shaming would-be pirates. 1-2-3 installed from copied disks prominently showed the name of the original owner every time the … Continue reading →

Posted in DOS, OS/2, PC history | 9 Comments

NT video miniport HD

Posted on March 9, 2012 by Michal Necasek

The video miniport driver for VirtualBox has been updated. The miniport now supports a much broader range of resolutions, up to 1920×1200. Color depths of 32, 24, 16, 15, and 8 bits per pixel are supported for all resolutions, although … Continue reading →

Posted in NT, VirtualBox | 23 Comments

AVX support disrupts WoW64 debugging

Posted on February 29, 2012 by Michal Necasek

Sometimes, the old and the new intersect in unexpected ways. After upgrading to a Sandy Bridge based system (Core i7) and Windows 7 SP1 64-bit some time ago, I noticed that debugging exceptions in 32-bit user programs didn’t quite work … Continue reading →

Posted in Windows, x86 | 18 Comments

LAN Manager vs. Windows 7

Posted on February 26, 2012 by Michal Necasek

I recently spent some time trying to access disks shared by a Windows 7 machine from various versions of OS/2 (running in VMs, although that’s not really relevant). The OS/2 clients ranged from OS/2 1.3 with LAN Manager 2.1 (1991 … Continue reading →

Posted in Networking, OS/2, Windows | 28 Comments

Undocumented VflatD

Posted on February 23, 2012 by Michal Necasek

The virtual flat framebuffer driver, or VflatD, was introduced in Windows 95 in order to ease development of display drivers. It was surprisingly poorly documented and the sample drivers did not illustrate its use very well. A short backgrounder may … Continue reading →

Posted in Documentation, VGA, Windows | 2 Comments

Kernel Debugging with VirtualBox

Posted on February 21, 2012 by Michal Necasek

Virtualization readily lends itself to debugging of low-level code that is difficult to analyze in conventional environments. It is also convenient for kernel debugging which would otherwise require two separate systems or at least a separate serial terminal. OS/2 Setting … Continue reading →

Posted in Development, OS/2, VirtualBox | 4 Comments

How to please WDCTRL

Posted on February 2, 2012 by Michal Necasek

As any user of 16-bit Windows knows, Microsoft Windows 3.1x in 386 Enhanced mode supported a coveted feature called 32-bit disk access (sometimes also called FastDisk). The “32-bit” designation was slightly misleading as there was no 32-bit data path to … Continue reading →

Posted in BIOS, Windows | 3 Comments

Retro development with aclock

Posted on January 29, 2012 by Michal Necasek

In the past few days, I embarked upon a project to port Antoni Sawicki’s aclock, a small text-based clock program (aclock stands for analog clock), to 16-bit Windows. While aclock itself has been ported to over 150 platforms, it is a … Continue reading →

Posted in Development, PC history, Windows | 14 Comments

What’s in a name… OS/2 or DOS?

Posted on January 27, 2012 by Michal Necasek

There have been many rumors that the name “OS/2” was chosen only shortly before the product was announced. It’s not entirely clear what the name would have been otherwise, but quite likely DOS 5; certainly DOS in some form. There … Continue reading →

Posted in Documentation, DOS, OS/2, PC history | 1 Comment