OS/2 Version 1.0 On PCEM
Microsoft originally licensed the UNIX operating system from Bell Labs and sold it under the Xenix name. After AT&T was deregulated in 1982, the new company took ownership and licensing of UNIX. As such, Microsoft had no control over the direction of the OS. Wanting more control over the direction of their next-generation OS, Microsoft entered into a agreement with IBM to co-develop DOS's successor. While Microsoft managed the Xenix code, they never wrote a high-end OS from scratch, and they needed IBM's help. IBM wanted in on the business and home markets that Microsoft understood much better than Big Blue.
Signed in 1985, the two companies started coding DOS's successor in 1987. Released in late 1987, OS/2 was something of a mixed bag. It could run programs that were larger than 640KB in size. It could also pre-emptive multitask applications that were specifically designed for it. It was also compatible with DOS. However, this new OS also had many shortcomings.
OS/2 v1.0 (and the other 1.x successors) were coded in 286 assembly language to conform to the features of the 286 processor. Microsoft wanted OS/2 to make use of the capabilities of the 386 processor, specifically the virtual 8086 mode. However, IBM rejected this idea because they made promises to customers that brought their 286 systems that they would receive this OS, even though Microsoft saw the 286 as a technological dead-end (they weren't far from the truth). Grudgingly, Microsoft would co-develop the 286 version with IBM. Also, IBM was really only interested in OS/2 as a way of selling new hardware. As such, when OS/2 got it's name, it matched with the PS/2 name of computers that IBM was about to release. The naming convention wasn't good in that it created the misconception that OS/2 could only run on IBM branded systems. Also, the Presentation Manager, the GUI that was suppose to run on top of OS/2, wasn't ready yet. As such, OS/2 v1.0 was text-only.
Because the 286 couldn't virtualize the 8086 like the 386 could, OS/2 could only run a single DOS session via a CPU reset. This session ran full screen and took over the whole computer. A badly misbehaving DOS application could still crash the whole computer. Since native OS/2 applications weren't that common, the DOS Compatibility Box (Penalty box as it was commonly referred to as) became a necessary evil. Also, by the standards of its day, it was very demanding. OS/2 v1.0 required a 286-based system with a minimum of 1.6MB of RAM and a 20MB hard-drive. Such a system was still a very expensive proposition in 1987. Not only that, the SDK (Software development kit) commanded a astronomical price tag of $3,000 (in 1987). And that didn't include the computer! Not surprisingly, the vast majority of software developers continued to stick with DOS.
However, OS/2 brought many ground-breaking features to the table. Applications could multitask and multithread with each other now. Programs could access hardware through system libraries provided by the OS (DLL's or Dynamic Linking Libraries). It had decent hardware support and could run on various systems. Their was of course that DOS Compatibility Box which still worked better than expected, despite it's limitation imposed by the 286 processor. Gordon Letwin, one the the key developers behind OS/2, details the development of this OS in his book, Inside OS/2, with is a highly recommended read.
OS/2 v1.0 is running on a 386 clone using the AMI BIOS and is equipped with the Intel 386 processor running at 16MHz, 4MB's of RAM, IBM VGA Adapter, and 30MB hard disk.
OS/2 (Wikipedia)
https://en.wikipedia.org/wiki/OS/2
Inside OS/2 Paperback
https://www.amazon.com/Inside-OS-2-Go...
Gordon Letwin
https://en.wikipedia.org/wiki/Gordon_...
Intel 286 - https://en.wikipedia.org/wiki/Intel_8...
Virtual 8086 Mode - https://en.wikipedia.org/wiki/Virtual...
OS/2 1985–1989: Joint development - https://en.wikipedia.org/wiki/OS/2#19...
Micro Channel architecture - https://en.wikipedia.org/wiki/Micro_C...
OS/2 Museum :OS/2 Beginnings - http://web.archive.org/web/2019040223...
OS/2 Museum : OS/2 1.0 - http://web.archive.org/web/2019040223...
OS/2 Museum : OS/2 1.1 - http://web.archive.org/web/2019040223...
OS/2 Museum : OS/2 1.2 and 1.3 - http://web.archive.org/web/2019040223...