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Why is OS / 2 hard to run in a virtual surroundings?

Due to sure reasons, OS / 2 is very difficult to nark work in a practical auto; some more complicated than DOS, Windows 3.x, Windows NT, Windows 95 OR many UNIX system-like in operation systems. Problems lie in the architecture of the axis and its history.

Freshman, we'll talk astir the effectuation features of the kernel and drivers of the old ( precise old) versions of OS / 2, then a bit about virtual machines, and after that, after a serial publication of manipulations, the author will launch IBM OS / 2 1.0 in the VirtualBox 4.3.8 virtual machine connected his Mac - KDPV. - approx. trans.

Well, first, older versions of OS / 2 (referring to Warp 3 and below) are difficult to run symmetrical on an cast-iron Pentium III and similar, it would seem, old machines. The operating system code contains many different cycles used to do time delays (orig. timing loops - approx. trans. ), which will fail on fast processors, causing outpouring errors during division and altogether sorts of others. Almost all 1.x versions are affected. Support for large IDE drives is also problematic, only OS / 2 should definitely not represent blamed for this ; at that time, the IDE standard was developing chop-chop, and we are talking about those multiplication when there were more disks, healed, 300 megabytes did not be at all, and in this see, virtualization even helps - it's much easier to move the slider in the virtual car settings to the left and create a virtual drive , let's say 120 megabytes, than running around and looking for a real, working hard repel of such lesser volumes.

Then, there are a number of problems specific to virtual environments. Let's start with the oldest versions of the Axis. IBM Operating system / 2 1.0 and 1.1 use the 286-style switch betwixt protected and real CPU mode. This is such a method acting that uses the BIOS code in order to resume the car in another modal value at a certain phase, because a computer hardware readjust of the processor is wont to switch betwixt modes ; most executives do not equal such executions, and are perceived as a calamitous error. Interestingly, Microsoft's OS / 2 1.x edition still detects the 386th CPU, and if one was plant, then another, much more efficient way to replacement between modes by ever-changing the CR0 register is used.

Even in versions 1.x, a very unusual drive driver was used, which determines the type of drive out, that is, its sized, based happening the data transfer speed of the controller. 3.5-inch disks with a capacity of 720 kilobytes are scan at a speed of 250 K / s, and a volume of 1.44 megabytes at a bucket along of 500 K / s. Just this is an iron flop. And virtual machines dress not hassle emulating so much fine details and allow the guest operational system, in our case, Axis, unlike a real drive, to read a 1.44-megabyte floppy, even if the drive control is programmed at a speed of 250 K / s. As a result, the driver thinks that a 720-K magnetic disk is inserted in the drive, which leads to comical errors, and in general to the unfitness to boot from a diskette.

With the 2.x branch, everything is a bit different: the drive driver is not so tricky and kit and caboodle fine, switching between the CPU modes uses a computer code specific to the 386th central processing unit ( support for 80286 was born in 2.x ), approx. but the office is broadly speaking no better. OS / 2 2.x is still experiencing timing issues, and on fast processors it may freeze at any time, peculiarly at an proterozoic stage of lading. And because the 16-chip real and 32-bit preserved mode code is mixed in the Half-Axis, IT is extremely important to correctly implement all aspects of the x86 architecture processors, and essential machines have problems with this. Quite a great deal, uncommitted, elusive bugs are set up, due to which OS / 2 ( meaning mainlyversions prior to Warp 4 - approx. trans. ) cannot kick and crop in a essential political machine without errors.

Other problem is the old (DOS-compatible) expressive style of error handling FPU ( Floating Stop Unit - a mathematical coprocessor for aimless compass point trading operations - approx. Per. ). OS / 2 non-SMP versions ( aka UNI - systems that do not use symmetric multiprocessing - Symmetric MultiProcessor system; the term applies to some software and hardware - approx. Per. ) Use the 8086-compatible method of generating a signal FERR#and converting IT to IRQ 19, as an alternative of victimisation # MF exceptions, as all modern operative systems serve today. Much a mechanism must be correctly emulated for Axis to work in a realistic machine.

Only the latest Axis versions (the so-called Convenience Packs - MCP1, MCP2 for the client and ACP1, ACP2 for the server) are buttressed as a Edgar Albert Guest in some virtual machines (information technology is known that in Virtual Personal computer and VirtualBox). By then, IBM ( MDM - MezhDelMash - International Commercial enterprise Machines;) - approx. trans. ) get already raked up problems with the dependence on the processor speed in some places, and hardware support has already reached the level suitable for working with today's virtual devices emulated away virtual machines.

The axle shaft works especially well if you turn information technology on ( forever become it on - approx.) hardware acceleration (VT-x and AMD-V) - MCP and ACP establis and work without any problems, and besides, Virtual PC and VirtualBox by this clock time released guest Atomic number 76 add- ons that add their computer hardware-accelerated video drivers, desegregation support mice, shared folders, and similar things that greatly improve the usability of the Axis in the practical car.

Everything, as always, is a matter of money and effort spent on resolution the problem. Almost anything can be decided if there is a real need for it.

Running IBM OS / 2 1.0 in a virtual simple machine

As I said, it is all incomprehensible why IBM revision cores, even with an 80386-compatible central processor, use the sure-enough, 286-style mode switch method, in which the CPU is hard readjust, and so execution continues from the BIOS, which was antecedently told from which place the carrying into action must continue. The Microsoft liberation of OS / 2 1.0 contained a kernel that used whenever accomplishable a new (faster) 386-only mode switching code from the very first version of OS / 2 SDK beta - April 1987.

And to make it even Thomas More interesting, the OS / 2 kernel is as wel famous for using an undocumented instructionLOADALL if it is running on 80286. Nevertheless, the IBM version of OS / 2 1.0 was running on 386 AT-clones of that time! How is this possible?

The keyword is BIOS. The BIOS of the machines along the 80386 processor is requisite to backing 286-trend mode switching, and this is standard functionality. And the mode switching code written for 286 also works on systems with 80386.

How it works on 80386 LOADALLis less obvious. BIOS developers soon realized that on 386-compatible processors, it was relatively easy to emulate a subset LOADALLby switch to real clock for a piece. It took Intel several long time just to at to the lowest degree gauge the existence of such a technique in BIOS, and therefore much behavior can just be called well-attested, but IT works on any system with an 80386-compatible processor.

IBM OS / 2 1.0 in VirtualBox 4.3

VirtualBox rendering 4.3 has finally erudite how to scat the ancient IBM versions of Bone / 2 1.0 and 1.1. Adjacent, VirtualBox 4.3.8 is used, the Host is Mackintosh Atomic number 76 X.

Create a new-sprung machine, the type of node OS should make up set to "Some other OS / 2". RAM put eight megabytes (OS / 2 1.0 demolishes the roof from large sizes). Put on a essential drive of 30 megabytes in size up - this version of Operating system / 2 still does not know how to divider more than 32 megabytes (but Operating system / 2 1.1 has already been taught). You can buoy do to a greater extent, but by all odds should not put more than 500 megabytes - there will be problems with the mismatch of geometries.

But that's not all. In Order to switch between the modes of the centered processor, which, as I have already mentioned more than once, is done through the reset of the processor, you need to pluck the settings of the virtual automobile so that the VirtualBox does non finish its operation with an wrongdoing when the CPU fails three multiplication. Usually, a three-time CPU fault means that the guest Osmium is no more able to resolve the problem and continue working, but for IBM OS / 2 1.0 / 1.1 this is part of regular operation. To change the virtual machine settings, you need to attend the VirtualBox directory and use the VBoxManage utility:

VBoxManage modifyvm <virtual_ machine_name> --triplefaultreset happening

And still need to patch the installation diskette.
Other, the axis is tramped with an error of division past cipher. Script-patcher in Python .

Done. Have a go. If everything went fine, the installer's title screen will pop up ahead you:

However, there is a chance that you will feature a problem with data format the partition in FAT, although the breakdown should go smoothly.

If you are unlucky, just grab any DOS diskette, load information technology into a virtual machine, and format the already created partition off in FAT16. Then bang into the installer again, and choose to use the existing volume, do non format it again. Obviously, this is a bug in the OS / 2 installer surgery in VirtualBox.

Then everything should go swimmingly, and you will only beryllium required to change the essential diskettes in the virtual drive as you install, and accept the default settings, which are very reasonable. After the installation mental process is completed, Operating system / 2 will launch TSHELL - School tex Shell - a text shell of protected mood that performs the function of unveiling programs and Roger Sessions, and switches 'tween OS / 2 and DoS sessions operating in multitasking mode.

And yes, this is in truth IBM OS / 2 1.0 :

Please note that if you have a server that does not support hardware fast virtualization (VT-x or AMD-V technologies), VirtualBox bequeath blaspheme that it is necessary to run OS / 2 and will refuse to start the virtual machine. Hardware virtualization is desirable, but Oculus sinister / 2 1.0 bequeath work without it (but for 2.0, Heave 3 and 4, information technology is mandatory). You can get around errors by mise en scene the type of invitee OS to either DOS or Unknown.

It would be riveting to know what strange nonclassical virtual machines (mean ones, that is, which calmly pass around modern 32-bit and 64-bit operating systems, instead than specialized 80286 emulators) are capable of launching the earliest releases of IBM OS / 2 - 1.0 and 1.1. Information technology is legendary that Microsoft Virtual Microcomputer 2007, although it is advisable for launching more modern versions of Bone / 2, since the hardware is emulated very close to the real one, is not able to course IBM OS / 2 1.0 and 1.1.

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From the interpreter:

Notes along spelling, punctuation and grammar, on translation bugs and inaccuracies (I often "ice-cream float" in those topics that Michal Necasek easy speaks to, which is why I, by the way, are curious in reading and translating his articles. If something is not obvious to me (and something was non obvious to me, especially when I was translating the late article ), I always Google and endeavor to figure it out, ask questions) I invite a subjective report. You are welcome.

I made a survey virtually whether you want to see articles about the Axis and related topics. The community has something to say, dead on target. The bigger problem is that the corresponding hub is not provided, and and then outlying there are not enough posts to present applications; Army of the Righteou's imag what posterior be finished this - there are really pretty well-behaved articles.

Those who answered "yes" I also ask you to scuttlebutt along the clause and indicate what kind of article you want to insure, what you are involved to love.

Postscript This is a combined translation of deuce articles , and so practically does non go into the "source" field, so it simply indicated the web site direct thither.

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GET Running IBM OS / 2 1.0 in a virtual machine: why it's hard to do / Sudo Null IT News FREE

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