Inside the OS/2 personality of Windows NT 3.x

I was a network administrator back in the 90's ans worked on both OSes. I still believe that OS/2 was the better OS for servers, unfortunately the better OS doesn't always win. Thanks for sharing

The personalities are better on IBM OS/2 than on Windows NT.

Nice video! I love this entire era of OSes, and I find OS/2 and early Windows NT particularly fascinating.

I have a very soft spot in my heart for the advanced 16-bit Intel OSs. At first I was stunned that a 16-bit PM add-on for NT existed, but seeing how buggy it was I totally get it now. It must have been something a major customer demanded and MSFT did the bare minimum to get it out the door.

So here’s a thing I have a distinct memory of reading about but I’ve never seen referenced elsewhere: that early NT would intercept I/O to a file named CONFIG.SYS (I think only from processes running in the OS/2 subsystem) and simulate it as though that file existed? So you would use an OS/2 editor to edit the (non-existent?) C:\CONFIG.SYS and it’d look like you were editing a real file with real settings representative of the running NT system. Then when the file was closed, it would translate the directives in it to native NT settings (and store them in the Registry, presumably). Anybody else recall that?

Another good video. Now I want to install NT 3.51 on one of my play machines. -former long term OS/2 user.

Very interesting, didn't know that existed for GUI OS/2 applications. Do you plan to bring on the NT 4.0 version as well?

NT was multi user from the out set OS/2 was at all. A totally different OS.

The NT OS/2 1.x subsystem was primarily to encourage previous Microsoft OS/2 1.x customers to migrate to NT instead of migrating to IBM OS/2 2.0. Microsoft did a pretty decent job too, with text mode OS/2 1.x apps (including their own OS/2 1.x dev tools) running transparently from within the NT Command Prompt. I tried running the WLO apps under Windows NT 4 via PMFILE. Despite being executed from the OS/2 side, they still load up on the Windows side. I didn't expect that. Particularly since PMFILE won't let you execute Win32 binaries. I also tried to force it from a Command Prompt (with PMSHELL running in the background) with "os2 /p clock.exe /c" but all the WLO apps just segfault.

Oh good a video on something totally rare and fringe! I'd always heard about the PM for NT but after years of searching when I finally found it, I was surprised about the 3.51 / 4.0 thing as well. I have to think there was a 3.1/3.5 versions as well. The WinOS/2 drivers were very involved to display Windows 3.0/3.1 on OS/2, so I'd have imagined it would have been just as difficult for PM on NT, and Microsoft just wasn't interested. Good stuff tho!

I am reading a book about the history of NT and this video is very good! Nice work!

NT3.51 also has a "Desktop Preview" which gives it the 95/NT4 style desktop. That may be worth a look if you can get hold of it

Good info, this is my favourite OS period

I worked with and supported the earlier OS/2 and NT packages. IBM insisted that the OS/2 HAD to work properly on a 286 machine, since they told big customers "Buy the IBM AT, and OS2 will be your operating system in a couple of years." -- Only problem was "how do we get from kernel mode to user mode?" issue. The only way to do it was have a triple fault and an entry for reset (in the dispatch table) to do that. There was no instruction to do it like there is in the 386. MS wrote NT for the 386 and newer processors... IBM demanded it work in a 286.. So they got forced to do the slow triple fault to go back to user mode from protected (kernel) mode... IBM figured that out when they took over OS2 development.... Warp was 386 happy... and didn't have the issues with a 16 meg of ram limit. (Adding the TCP/IP stack on OS2 1.3 got you down to less than 50k free, which was an issue for people wanting to run web servers....

Interesting that it is showing NT Version 4.0 (Build 1057) in 14:12! Do you know hat happened here? After using the last known good config it's back to 3.51.

I wonder on what software and hardware microsoft was developing the FIRST windows NT (writing code, compiling, debugging, testing, etc). I wonder because, as is well known, microsoft is locked in its bubble and pretends that other operating systems do not exist. This "closed" mentality was more evident in previous decades.

Correct winNT IS os/2 userland base WITH VMS kernel on top system to run multiple systems like posix, win32, os2 apps all that is completely different from ibm os2 is only limited to dos and win16 to win32 in later versions

NT didn't emerge from OS/2 at all. Dave Cutler (the guy who created NT) hated OS/2 and has spoken of it fairly derogatorily.

I have the PM plug in for windows NT 3.1 the 1.0 version of it. And also have the later version for NT 3.51/4.0

I wonder which user the programs run under PM system, when it is running as a service. I hope not SYSTEM like the service itself ;)