Category Archives: Virtualization

Alt Insanity

Several times, a question came up how to synthesize keyboard input to a remote system given a text string. The remote system is typically but not necessarily a VM. That sounds like something which should be trivial, yet it is anything but. … Continue reading

Posted in Virtualization, Windows | 13 Comments

Semantic Differences, Microsoft v. Microsoft

While comparing the behavior of various versions of old Microsoft C compilers, I tried building a trivial hello-world type program with CL.EXE from Microsoft C/C++ 7.0 (March 1992) running on top of a 32-bit Windows Server 2003. This seemingly trivial … Continue reading

Posted in DOS, Microsoft, Virtualization | 5 Comments

IBM OS/2 1.0 in a VM

As previously mentioned, IBM’s OS/2 1.0 and 1.1 is extra unfriendly to modern hypervisors. To recap, there is a curious difference between IBM’s and Microsoft’s kernels in OS/2 1.0/1.1 with regard to mode switching. For reasons that aren’t very clear, … Continue reading

Posted in IBM, Microsoft, OS/2, VirtualBox, Virtualization | 22 Comments

Preserving Floppies

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 | 19 Comments

Virtualizing QNX 2

(Note: This is a guest post from Tenox) Enter 1988… around that time Microsoft just released MS-DOS 4.01 and IBM shipped OS/2 1.1. Compare to the others, this OS was years ahead of its time pretty much on every aspect. … Continue reading

Posted in QNX, Virtualization | 6 Comments

An old idea: x86 hardware virtualization

It is well known that virtualization of the x86 architecture is an old idea. The Intel 386 processor (1985) introduced the “Virtual 8086” (V86) mode, enabling users to run real-mode operating systems as a task within a 32-bit protected-mode operating systems. … Continue reading

Posted in 386, Intel, Virtualization | 14 Comments

Solaris 2.5.1 and 2.6 crashes on modern Intel CPUs

I recently found that Solaris 2.6 and 2.5.1 does not work when run in a VM on a modern Intel CPU (Sandy Bridge generation Core i7), or to be exact fails most of the time (about nine times out of … Continue reading

Posted in Solaris, VirtualBox, Virtualization, x86 | 12 Comments

OS/2 Warp installation pitfalls

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 … Continue reading

Posted in OS/2, Virtualization | 10 Comments

Interrupt 68h and EMM386

While working with a modified BIOS image in a virtual machine, I ran into mysterious hangs when trying to load an old version of EMM386.SYS from MS-DOS 4.01. A newer version of EMM386 did not exhibit the problem. A quick … Continue reading

Posted in BIOS, DOS, Virtualization | Leave a comment

The Fixed Disk Parameter Table

The Fixed Disk Parameter Table, or FDPT, is a structure primarily used by the BIOS in IBM compatible computers, but is also of critical importance to some (especially older) operating systems which do not use the BIOS. The FDPT was … Continue reading

Posted in BIOS, PC architecture, Virtualization | 3 Comments