Linux, Unix, Windows, and OS/2: How Demand Beat Design

The Rise of UNIX and Portable Computing 

“OS/2”

There. I said it. And I’ll say it again… but not right away so I don’t seem too fixated on something that inexplicably became an “also ran.”

You know what it proved? A bunch of things, beginning with the fact that IBM is not a consumer electronics company. But also that when consumers are concerned, demand may win over design.

Dr. Fred Brooks, who was in charge of the creation of the IBM System/360 mainframe and OS/360 operating system (not to mention JCL – seriously: don’t mention it) wrote two great books, decades apart. First, “The Mythical Man-Month” (see https://en.wikipedia.org/wiki/The_Mythical_Man-Month) about how writing software doesn’t behave like traditional construction. Then he wrote “The Design of Design” (see https://en.wikipedia.org/wiki/The_Design_of_Design). It showed how the mainframe’s visionary design was essential to its amazing success and persistence.

When Demand Beats Design 

I used to work for a company that made mainframe software (not that they always admitted it) whose motto was, “Software Superior by Design.” Colleagues and customer liked to rephrase that as “superior by acquisition,” but, whatever.

Meanwhile, the platforms that filled the limitless consumer electronics green fields left unoccupied by the mainframe showed superiority by demand. It was never a fair fight, no matter how carefully designed OS/2 was.

So wtf? “What’s the functionality” that made Unix, Windows, and Linux win where IBM’s scrupulously-designed OS/2 got left out in the cold? And why didn’t the mainframe platform now known as IBM Z also lose?

I’d compare IBM to Sony and OS/2 to Beta, but if you get the reference, you already know everything else in this article.

Why UNIX Spread So Fast

Here’s the thing: UNIX, written to host computer games, arrived only about half a decade after OS/360. Originally it was written to work with a DEC PDP instruction set. But then it got rewritten in C, and because it could be recompiled for any hardware platform that had a C compiler, it took off wherever people had hardware and no accessible operating system – especially at underfunded academic and government institutions.

Three initial things to know about UNIX:

1. First, it has a tree-structured file system.
2. Second, the separator between directory names in a fully-qualified file name is a forward slash (you know: the one in URLs – “/”).
3. Third, it has a command-line environment for running programs and issuing commands. Unlike DOS –

How Windows Borrowed — and Diverged 

OK, MS-DOS (and its red-headed step-sibling IBM DOS) – there are actually a selection of different command line environments – or “shells” – on UNIX.

Three initial things to know about Windows are:

1. It inherited the MS-DOS command line environment
2. It has a tree-structured file system for each device attached to it
3. It uses the backslash (“\”) for a separator between directory names

Was there some implicit reference to the UNIX environment in MS-DOS and its predecessors? As Mark Twain observed, history may not repeat itself, but it sure does rhyme.

Anyway, while MS-DOS and its progeny were struggling forward to find a consistent graphical interface, UNIX was struggling to find its rightful owner, leading to lots of copyright issues that MS-DOS was able to sidestep with a backslash.

The Secret Weapon: The Kernel 

But one thing UNIX had that MS-DOS didn’t was a kernel: a persistently running core in the “background” (i.e. unattended), while MS-DOS was essentially a command line, file system, and a few utilities that all ran in the foreground.

Initially, rather than writing their own operating system for IBM PCs as they did for the mainframe, IBM had invited Microsoft to provide the first: MS-DOS, which had been acquired and enhanced based on pre-Microsoft art. Then IBM asked Microsoft to actually write the next great operating system that would be, er, superior by design. 

I know. I was there when IBM and Microsoft announced this new PC operating system to the world. I was in a hospitality suite along with many other nerds, watching a screen that had been set up in the corner, where we could all see it just by gazing upwards. I remember the blinking cursor in the upper left corner. Because that’s all there was to remember (plus some excellent bacon-wrapped scallops). Apparently, Microsoft had not produced the desired result.

IBM, Microsoft, and the OS/2 Split 

So, IBM fired Microsoft and went about making its own version of OS/2. And Microsoft, which had already put together a graphical interface for MS-DOS called “Windows,” decided to create its own graphical environment with a “real operating system” underlying it. And they hired Dave Cutler, one of the chief architects of VAX/VMS at Digital Equipment Corporation, and incremented each of the letters in VMS by one to create “WNT” or “Windows NT,” which had its own persistent background processes that took it beyond the superficial.

Linus Torvalds wasn’t impressed. He didn’t like the copyright issues with the preponderance of UNIXes, and he didn’t like, er, things about Microsoft’s environment. But he also didn’t buy into IBM’s “ultimate” PC OS concept. So he created his UNIX-like Linux from scratch, which, like Windows, was initially intended exclusively for the Intel PC hardware platform.

Why Linux Changed Everything 

Unlike Windows, Linux was not proprietary, and being written in C, it was portable, and so it began to get recompiled for every other environment – eventually ending up on the IBM Z mainframe.

There’s one other thing worth noting: the kernel’s secret recipe. UNIX, and consequently Linux, had a real operating system aspect of persistently running code that was always on, command line notwithstanding. Then Apple adopted the UNIX Mach kernel for their OS as well, effectively making it also a UNIX.

So, UNIX-like, Windows, and IBM Z: two quirks that were successful by consumer demand, and one that was designed for the ages, but has plenty of whimsy emergent from its nerdy history: these ended up ruling the world of business IT. 

And I don’t know why OS/2 didn’t win, but I do know that OS/360 and its IBM Z successor didn’t lose.