OS Evolution
In my early work on mainframe computers I saw operating systems evolve from primitive proto-OS’s like the 1620’s Monitor I system, through batch operating systems like the Burroughs MCP and IBM’s OS/360. OS/370 added virtual storge. VM/360 made the switch to interactive time-sharing systems.
My favorite operating system from that era was DEC’s Vax/VMS. VMS was interactive, had a well-thought out API and user interface that made it a pleasure to program and to use.
Perhaps the most significant OS from this era is Unix.
(Note that the above screen shot is contemporary. The command-line syntax used by UNIX has changed little from its inception in the 1970s to the present day.)
My neighbor across the street, Peter Neuman, used to work at Bell Labs in the days when UNIX was being developed there. He told me the story of how he convinced Ken Thompson, the inventor of UNIX, to add multi-programming to the OS. Thus he changed the world. UNIX would not have the popularity it does today if it could only run one program at a time.
Personal computers followed many of the same trends as mainframe OS’s and did a kind of rapid replay of the evolution of large-system software: The SOL and Apple had primitive proto-OS’s. CP/M, like UNIX, was portable (although not as portable as UNIX. UNIX was written in C, whereas CP/M was written in assembler, and was limited to Intel 8080 processors).
When the IBM PC was released it came with MS-DOS, which was essentially a 16-bit rewrite of CP/M.
The second release of MS-DOS added hierarchical directories to support the hard disk. This invalidated the limited file-name size inherent in the CP/M-style APIs. So an entire second API was introduced that was clearly based on UNIX. In fact the additions to the command interface to support directories were also clearly derived from UNIX.
When the Macintosh came out, its GUI (“point and click”) interface was clearly superior to the traditional command (“remember and type”) interface. So Microsoft came out with Windows.
The screen shot above is from Windows 1.0. In this version there were only “tiled” windows; windows did not overlap.
Windows was not a separate operating system. Rather it was an add-on to MS-DOS.
Windows didn’t really take off until Windows 3.0. That version took advantage of hardware advances in the Intel 80386 chip that allowed it to use virtual storage. This made a huge difference in performance and functionality.
The next step was Windows 95. This was a repackaging of Windows and MS-DOS code into one package: Windows had become an operating system. The user interface was also greatly improved for Windows 95. Windows 95 also switched to Win32, the 32-bit programming interface already in use in Windows NT. Previously, Windows 3 had used Win16, which Windows 95 also supported for backward compatibility.
At the time Windows 95 came out, I was working at Tandem. Tandem had an expensive and well provisioned television studio which they used for in-house communications. I remember that Apple rented the Tandem studio to do a satellite broadcast to Macintosh users’ groups world-wide. It seemed like the major message of that program was bashing Windows 95. They had a copy of the Windows Administrators Guide which was admittedly a very thick book. They used that as evidence of how hard Windows was to use.
Windows 95 was followed by Windows 98.
This was in tern followed by Windows ME (Millennium Edition):
ME appears to be the end of this product line, but not the end of Windows.
At one point Microsoft’s strategy, along with that of their partner, IBM, was to abandon Windows in favor of an IBM-backed operating system, OS/2, which was to go with IBM’s new PC platform, PS/2 (Personal System/2). The PS/2 and therefore OS/2 was 16-bits. But then, Intel began producing 32-bit processors, starting with the 80386. Microsoft and IBM planned to come out with a new operating system, which they dubbed “New Technology” or NT. It was to be a 32-bit version of OS/2. But then, IBM and Microsoft had a falling out. IBM took OS/2. Microsoft kept NT which they re-directed to be a 32-bit version of Windows.
The first version of NT to be released to the public was NT 3.0. The first version to be successful was NT 3.5. 3.5 contained the Windows 3.0 look and feel. In the mean time Microsoft had released Windows 95 with a much improved look and feel. This made NT 3.5 look old-fashioned by comparison.
Then Microsoft came out with NT 4.0 which contained a Windows-95 like user interface.
This was followed by Windows 2000. (The NT team had beaten the Windows 9x team to grab the “Windows 2000” name which is why the Windows 9x team had to use “Windows ME” for their turn-of-the-century product.)
Windows 2000 was followed by Windows XP which again made radical changes in the look and feel:
