55 lines
3.5 KiB
Markdown
55 lines
3.5 KiB
Markdown
---
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layout: post
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title: OS/2 1.0
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date: 2014-12-04 11:00:00
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category: OS/2
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permalink: /blog/2014/12/04/
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---
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Exciting news for OS/2 fans: PCjs (v1.16.1) is now able to run OS/2 1.0 on
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[IBM PC AT Machine Configurations](/devices/pcx86/machine/#model-5170-machine-configurations). This is the culmination
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of recent work in PCjs to fully emulate the Intel 80286 processor and 16-bit protected-mode, including undocumented
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features like [LOADALL](/pubs/pc/reference/intel/80286/loadall/) and triple-fault resets.
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For a quick demo, try the [OS/2 1.0 Debugger Disk](/disks/pcx86/os2/misc/1.0/88286/). In a few seconds,
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you'll see a very rudimentary OS/2 shell (a slimmed-down version of the OS/2 Program Selector) that allows you to
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start the protected-mode command interpreter ("Start a Program") or the real-mode command interpreter ("command.com").
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[<img src="/blog/images/os2-debugger.jpg" alt="OS/2 1.0 With Kernel Debugger"/>](/disks/pcx86/os2/misc/1.0/88286/)
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As an added bonus, the Model 5170 machines feature two serial ports, with COM1 connected to a simulated serial
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mouse and COM2 connected to the **Control Panel** output window.
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Once you've booted the [OS/2 1.0 Debugger Disk](/disks/pcx86/os2/misc/1.0/88286/) from the assortment of
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[OS/2 Prototype Disks](/disks/pcx86/os2/misc/), you can click on the **Control Panel** output window, press Ctrl-C, and
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find yourself magically transported into the OS/2 Kernel Debugger. The **Control Panel** display is functioning
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as both the output window for all PCjs messages and PCjs Debugger commands, as well as a serial input/output device
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(aka "Dumb Terminal") for any software inside the machine communicating via COM2: in this case, the OS/2 Kernel Debugger.
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> SIDEBAR: You can perform similar tricks with DOS in these machines. Boot any DOS disk (version 2.00 and up)
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and type "CTTY COM2" at the DOS prompt. All DOS input/output will now be routed to the **Control Panel** display.
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To restore control to the the machine's keyboard and video display, type "CTTY CON".
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Type "?" for a list of all OS/2 Kernel Debugger commands. Type "g" to continue running OS/2. Make sure you type all
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OS/2 Kernel Debugger commands into the **Control Panel** output window. Commands typed into the input box *beneath*
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the output window are processed only by the PCjs Debugger.
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When a fault occurs, OS/2 normally displays a "TRAP" message; however, when the Kernel Debugger is running, it
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intercepts the fault and displays the faulting instruction. But the PCjs Debugger has ultimate control: using
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the "m fault on" and "m halt on" commands, the PCjs Debugger will display and halt on any fault first. If you want
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PCjs to deliver the fault to OS/2, single-step over the faulting instruction and then continue.
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There are still a number of known issues running OS/2. For example, when attempting to install OS/2 1.0 from the
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installation diskette images onto a hard disk image, OS/2 successfully formats the hard disk and copies the files from
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the first two diskettes, but usually while copying files from either the second or third diskette, the process stops.
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There's no crash -- it simply stops copying files and never finishes. My best guess at this point is that some
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interrupts are being dropped.
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Similarly, if a machine running OS/2 1.0 is left unattended for a few minutes, it may stop responding. Again, there's
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no crash or other indication of a problem. The machine simply appears hung. "Ctrl-Alt-Del" and "Reset" buttons still
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work.
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The journey continues.
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*[@jeffpar](http://twitter.com/jeffpar)*
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*December 4, 2014*
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