IBM OS/360 to Windows 3.1: Software that Changed Computing Forever


Last month, we took you on a tour of computing's most venerated classic PCs. In our classic PC hardware retrospective , we highlighted the computers that deployed the innovations we take for granted today. But just as a car without gas is just roadblock, computer hardware without software is essentially paperweight. And while it’s true that the hardware is the visually sexier component of a system, the software is equally important and often more challenging to create. Today, we take a look at the history of early computer software, from the first character-based interfaces to the last pre-32-bit OSes (yes, Mac OS included). We also spotlight the notable programs that ran on these various platforms, including the first productivity and design applications. And because we're avid gamers, we couldn't neglect video gaming's contribution to the software world -- we included the firsts of each gaming genre.

The soul of any computer is its operating system. This software component is the basic interface between the hardware and/or hardware BIOS (Basic Input/Output System) and the rest of the software. It provides the basic capabilities such as user interaction, storage management, communications and so on.

Early Operating systems were fairly primitive with text-based interfaces, limited I/O, few storage options and marginal expandability. This was appropriate for the limited hardware of their day (who wants a 32K operating system on a 48K system?) but on today’s seemingly unlimited platforms we’re looking for more power. The evolution between there and here has been fast, furious and interesting.

Of course there were many, many other operating systems that we didn’t include, from AppleDOS to OS/2 to BeOS to GEM and tons of others in between. There were also a large number of machines that used BASIC (the programming language) for disk control effectively embedding the Operating System at that level. Our story focuses on the software that had the biggets impact on everyday consumers -- and the many feature milestones that give us the modern computing experience.

Photography by Karen Klein

Pre-Software: Hardwire Programming

Circa 1950

Programming is really just about moving bits of data from place to place in an orderly fashion. The current state-of-the-art involves using microprocessors and related controller chips in concert with sophisticated software to force very small bursts of electrons to do interesting things.

Before processors and ICs these chores were often relegated to vacuum tubes and similar devices. Before programming languages, and even, at times, alongside of them, the current was manipulated by hard wiring or by routing wires with plug-boards that required rewiring as the programming requirements changed.

Pre-Video Gaming: Tennis for Two

Circa 1958

In the 1950s the infrastructure for video games just didn’t exist. There were no microprocessors, computers were multi-ton behemoths and personal computers were science fiction devices.

But, in 1958, William Higinbotham, a Manhattan Project veteran, developed an interactive demo called Tennis for Two that had people lining up at Brookhaven Labs open houses.

The game consisted of an oscilloscope screen and a pair of controllers wired into an analog computer. It wasn’t quite what we’d consider a computer game, per se, but it was a computer being used for entertainment as opposed to ballistics tables so it certainly qualifies as at least a precursor!

Game Spotlight: Spacewar

Circa: 1962

Back in the early 1960s Digital Equipment Corporation installed a few of their new PDP-1s at institutes of higher learning hoping that the brilliant students would come up with some unique use for them.

They probably didn’t plan on what would happen with the MIT machine. Steve Russell and several other students with an overdeveloped sense of sci-fi wrote a space war game, complete with projectiles and hyperspace. The game, a two player space battle around a star, was popular enough to prompt a commercial version, installed at the Stanford Student Union, in 1971.

Nolan Bushnell was so taken by the game that he went straight into the business and soon founded Atari. SpaceWar is considered by many to be the first video game.

IBM OS/360

Circa: 1964

With the introduction of the IBM System 360 the rules for software were changed. Earlier mainframe systems were re-architected with each new model and software written for one was almost never compatible with another. IBM decided on a new plan. The System 360 was actually a whole line of computers with performance at the high end being more than ten times the performance at the low end.

Throughout, however, the machines ran the same OS and other systems software and used the same development languages.

So as a business grew it could expand available computing power without rewriting their software.


Circa: 1969

Tucked away in a corner of Bell Labs there once sat a forlorn DEC PDP-7 in need of a purpose. Ken Thompson, Dennis Ritchie and a bunch of other Bell Labs folks put the machine to work and, in the process, cobbled together an operating system to make the work easier.

Over time the core of the OS was expanded, rewritten (in C) and then unleashed upon the world as a free, open source project.

From that came Xenix, Linux and a host of UNIX variants that evolved, merged, forked and otherwise developed into the various Unix flavors we have today.

Game Spotlight: Pong

Circa: 1972

Pong was one of the first games created by Nolan Bushnell’s newly created Atari Corporation in 1972. The game was a simple two-player ping-pong game in which each side used a paddle to pass a ball back and forth.

The black-and-white graphics were exceptionally crude but the game-play and competition were addictive which meant that the consoles, installed in bars, coffee shops and game rooms, were always busy.

Atari released the game on home consoles in 1975 (Magnavox had released a similar home game prior to Atari’s arcade version) and eventually released their 2600 home video game console and computer lines; all of which owe their existence to a ball and two paddles.

Application Spotlight: SuperPaint

Circa: 1973

The Xerox Palo Alto Research Center (PARC) was a hotbed of innovation during the early years of personal computing. From their labs came the laser printer, the mouse and the Graphical User Interface.

One element of the latter that caught on all by itself was the idea of a paint program. People are natural doodlers and Xerox PARCs SuperPaint proved that computers could be as good as the margins of a notepad.

Of course paint programs really aren’t just for doodling and almost all of the features we’ve come to expect from a real drawing package came from SuperPaint including color palette manipulation, custom paintbrushes and drawing tools, polygon drawing tools and the like.

The Computer History Museum in Mountain View California still has the original hardware for the SuperPaint system.


Circa: 1974

In 1974 Gary Kildall of Intergalactic Digital Research (later Digital Research, Inc.) created his Control Program/Monitor for 8080 based systems.

The easy to use, character-based operating system, joined to machines like the MITS Altair and other early S-100 boxes, helped make computers more approachable and contributed to their success.

CP/M was eventually commercialized and “Monitor” was replaced by “Microcomputer” in the acronym. The operating system was modular enough that various vendors could easily customize it to their specific hardware and for many years CP/M dominated the personal computer space running on hundreds of different machines from S-100 bus systems to portables.

Game Spotlight: Crowther and Woods' Adventure

Circa: 1975

Early Personal Computers rarely had video displays and when they did they were rarely any standards. In that environment most of the earliest games tended to be text based.

In 1975, avid caver and D&D fan Will Crowther wrote a text based adventure program based upon Kentucky cave systems he was familiar with. Crowther’s game spread and was soon discovered by Don Woods who greatly expanded it with the consent of the original author.

Go down, get knife, kill troll, get cage, lamp on, xyzzy. In between two word commands the adventurer was treated to descriptions of a detailed imaginary world of treasure and exploration with not a little bit of danger. This Adventure was the first of many “interactive fiction” games.

Application Spotlight: Electric Pencil

Circa: 1976

These days word processing is an expected use of a Personal Computer but this wasn’t always the case. Early text editing was clumsy and was often hampered by the medium used to communicate with the earliest computers – typically old teletypes, dumb terminals or similarly cumbersome devices.

Electric Pencil, written by Michael Shrayer in 8080 Assembly Language, was designed to work, instead, with the earliest graphics cards on machines like the Altair 8800, IMSAI 8080 and Sol-20.

Most expected features were present in this software including find and replace and various formatting options but the application was text based. WYSIWYG was a still several years away.

Application Spotlight: dBase II

Circa: 1978

In 1978 C. Wayne Ratliff, borrowing from his mainframe experience, created a database program in order to try and track and win his company football pool.

In early 1980 he entered into an agreement with Ashton Tate to sell the product as dBase II (there was never a dBase I.)
This program quickly grew to define what was expected from a personal computer database and database language. Before the advent of SQL it was the de-facto database standard across PCs of all kinds.

Millions of copies were sold for CP/M, Apple, DOS and a wide variety of other platforms and the compatibility was incorporated into numerous other products including FoxPro and Clipper.

Countless programs are still in use today running newer versions of the xBase standard.

Application Spotlight: VisiCalc

Circa: 1979

While at the Harvard Business School Dan Bricklin saw a chance to make a program that would remove the tedium from creating financial models. This program evolved into VisiCalc for the Apple ][ computer.

VisiCalc was, as it turns out, the first “Killer App” and it redefined what people could do with computers, instantly turning them from toys to tools in the eyes of business people the world over.

VisiCalc was quickly ported to numerous other platforms and was eventually copied with applications like SuperCalc, Multiplan, Lotus 123 and eventually Excel building on the original concept.

Application Spotlight: Wordstar

Circa: 1979

WordStar was released by Micropro International in 1979. Designed for CP/M systems using dumb terminals, all of the software functions, including cursor movements, had to be controlled by the alphanumeric keyboard and the few “special” keys such as Ctrl and Esc common to most of these systems.

The company was formed by two engineers who left IMSAI to write the software and after its release it quickly became the top selling word processor and, for a time, the top selling program.

As a word processor WordStar did very well as it was configurable and expandable which allowed it to work with a variety of systems, printers and storage devices. There was even a SpellStar add-on; one of the earliest spell checkers.

WordStar was ported to the PC shortly after it was introduced but was soon eclipsed by packages designed specifically for that platform.

Game Spotlight: Zork/Infocom

Circa: 1979

Inspired by the Colossal Cave Adventure a group from MIT founded a company to produce similar interactive fiction.
They made several enhancements to the genre; they created a “z-code” engine for the games that allowed them to port between platforms easily and they produced a parsing engine that could understand substantially more complicated statements.

The first Infocom game was Zork I which became a wildly popular text adventure. The company went on to expand the Zork franchise and released numerous other games using the same technology.

Game Spotlight: Mystery House

Circa: 1980

Ken and Roberta Williams were also inspired by the Colossal Cave and set out to recreate their experience with that game for the Apple ][.

Taking advantage of Apple’s graphics they created the first-ever visual adventure game: Mystery House.

The game sold exceptionally well (well over 10,000 copies) and their company On-Line Systems (eventually Sierra Online) became an overnight success.

Game Spotlight: Rogue/Hack/NetHack

Circa: 1980

Rogue was an early, dynamic dungeon crawl rendered in text characters (K was a Kobold, Z was a Zombie, etc.) where the player battled deep into a dungeon, exploring while collecting food and magical items, to ultimately return with the Amulet of Yendor.

Rogue was followed by a more advanced version called Hack which evolved into Net Hack. Ultimately this genre would include real graphics and would result in titles like Diablo which, while they added substantially to the user experience, were essentially the same hack and slash dungeon crawl concept.

Game Spotlight: Flight Simulator

Circa: 1980

The Apple ][ was a fairly powerful machine for its day but a 1 MHz 8 bit processor and 48K of RAM wasn’t enough juice for a real flight simulator, was it? It turns out that a combination of that hardware and the programming brilliance of Bruce Artwick was, in fact, more than enough juice.

Bruce came up with a scheme which allowed him to offer credible frame rates on the “out of the window” view while keeping the lower gauges view updated as well.

The whole thing was very playable in spite of the relatively crude (by today’s standards) graphics. Bruce’s company, Sublogic, eventually licensed the technology to Microsoft and, in 1982, the Microsoft Flight Simulator family was born.
More than just a game the MS Flight Simulator became the de-facto standard of IBM PC compatibility for years after its introduction.


Circa: 1981

IBM originally wanted CP/M to drive their new PC to success but a culture clash at the initial meeting with Digital Research rendered a deal unlikely.

Enter Bill Gates and the young Microsoft Corporation. Through family contacts Gates had learned about the pending PC and offered an Operating system for it.

This OS, as it turns out, was one he had to purchase from a small outfit called Seattle Computer Products. Microsoft renamed their QDOS (Quick and Dirty Operating System) to MS-DOS and licensed it to IBM (who called it, unsurprisingly, PC-DOS) while retaining the right to market it to others.

This latter coup proved brilliant as Microsoft leveraged a $75,000 investment into a multi-billion dollar empire in a few short years.

DOS 1.0

Circa: 1981

DOS (Disk Operating System) was originally introduced as version 1.00 with basic functionality that closely mirrored (some would say plagiarized) CP/M.

A few early bugs prompted the release of a version 1.05 patch followed quickly by version 1.10 in early 1982 which added support for higher capacity floppies by increasing the number of tracks per sector.

IBM was the only customer for version 1.00. Compaq and other clone makers came in under later versions.

Game Spotlight: Ultima

Circa: 1981

The Ultima universe, Britannia, was born in 1981 when Lord British AKA Richard Garriot and Ken Arnold, both teen geeks working at a ComputerLand, released a fantasy/role playing game they’d developed to follow Garriot’s success with Akalabeth.

The game was wildly popular for the day selling tens of thousands of copies for the Apple ][ and, eventually, the Atari 800 and other systems.

The game also spawned a massive franchise boasting nearly a dozen episodes including the addictive Ultima Online, one of the earliest and most prolific MMORPGs.

DOS 2.0

Circa: 1983

The release of the IBM PC/XT in 1983 prompted an upgrade to DOS which supported subdirectories and hard drives.
The version was updated with bug fixes and some new functionality in version 2.1.

DOS 3.0

Circa: 1984

DOS 3.0 added support for the new High Density 5.25” floppy disks introduced with the IBM PC/AT while further tweaking much of the underlying functionality.

Later releases included version 3.2 which supported the 3.5” floppies as they were starting to become popular and version 3.31 which finally supported hard drives larger than 32MB.

Application Spotlight: MacPaint

Circa: 1984

While there were other earlier paint programs for PCs prior to MacPaint there were none quite as popular, memorable or symbolic of their era.

Perhaps because the application was often used by Apple as a screenshot in their advertisements (who can forget the early Mac saying “hello” to the world from the page of a magazine) MacPaint helped represent the ease of use and creativity that Apple wanted to brand into their computers.

Game Spotlight: The Ancient Art of War

Circa: 1984

Broderbund Software’s introduction of The Ancient Art of War set the Real Time Strategy game loose on the gaming community, rendering it inert with addiction.

The game, in which units of various types of troops engaged in campaigns for supremacy had most of the elements of modern RTS games. Troop types had various strengths and weaknesses and the outcomes of battles hinged on the effectiveness of a given force which, in turn, was impacted by a variety of factors such as hunger and morale.

The popularity of The Ancient Art of War led to numerous other RTS games including Dune II, which defined currently familiar game-play.

Modern RTS games such as Company of Heroes, Warcraft, Starcraft and Command and Conquer are all descended from this lineage.

MacOS 1.0

Circa: 1984

MacOS was Apple’s interpretation of the Graphical User Interface for the masses. Apple’s previous GUI for the Lisa had most of the same elements (and, in some cases more) but was tied to a far more expensive platform and, thus, enjoyed far less success.

MacOS has undergone a substantial evolution from its 1984 roots to the modern OS X versions. System 1.0 was fairly slow mainly due to floppy-only access and the relatively underpowered 128K Macintosh it was introduced with. It did, however, represent a true mouse-driven, bitmapped GUI for a reasonable price.

Borrowing heavily from their own Lisa OS which borrowed, in turn, from the Xerox Alto the Macintosh OS mainstreamed the GUI and reset expectations for how a personal computer should work.


Circa: 1985

The Commodore Amiga, introduced in 1985 after a tumultuous development process, came to market with one of the most advanced operating systems of the day.

While the early Macintosh systems were black and white and single-tasking and Windows 1 was barely out the door Commodore had a multi-tasking, multi-windowed color GUI that took full advantage of the power of the Motorola 68000 chip as well as the various specialized controllers in the Amiga chipset.

The AmigaOS user metaphor was a bit different - being styled after a workbench rather than a desktop with drawers instead of folders - but it was functional and became very popular with large base of users many of whom still swear by it today.
The Amiga died in 1994 with the bankruptcy of Commodore but AmigaOS lives on.

MacOS 2.x

Circa: 1985

System 2 was an incremental improvement over System 1 with a later release (2.1) offering the first hierarchical file system for the Mac along with support for the new external hard drives that were in high demand.

AppleTalk was also added to support the new Apple LaserWriter and to allow for networking Macs. Performance was found to be improved with the addition of more RAM on the “Fat Macs” with 512K and up.

Application Spotlight: PageMaker

Circa: 1985

The logical next step to word processing combined with a GUI was, in retrospect, personal or desktop publishing.
In 1985 that wasn’t nearly as obvious but a small company called Aldus provided Apple with the “killer app” their new Macintosh line needed: PageMaker - the world’s first desktop publishing program.

Brochures, newsletters, menus and all sorts of other print items could be made by mom and pop using this application and a LaserWriter without the need of a professional print shop.

An entire industry soon developed around the concept with applications for type management, image editing, clip-art and more springing up to meet the needs of a new breed of at-home graphic artists.

Windows 1

Circa: 1985

Microsoft started work on a windowed GUI as early as 1981 with documented prototypes demonstrated in 1983. By the time it was released in 1985 Windows 1.0 was a fairly limited DOS shell that had a lot of competition from products like Digital Research’s GEM and VisiCorp’s VisiOn.

The first versions of Windows required DOS for installation and offered limited functionality beyond the basic text-based DOS shells of the day.

Windows 1 was pretty, relative to the character-based DOS, but it wasn’t compelling and, in the end, it wasn’t popular.

MacOS 3.x, 4.x, and 5.x

Circa: 1986-1987

The third generation Mac Operating System coincided with the introduction of the Mac Plus and offered the full integration of the Hierarchical File System along with the SCSI support and other features.

System 4 was introduced alongside the Mac II and added support for the various new technologies introduced with that machine including color, the Apple Desktop Bus and the Motorola 68020 processor.

Most significant in System 5 was the addition of the new “multi-finder” allowing multiple programs to be run and to share system resources in a cooperative multi-tasking environment. As with most prior releases, System 5 was evolutionary, not revolutionary.

Windows 2

Circa: 1987

The second Version of Microsoft’s Windows wasn’t much different from the first, but the significant difference – an ability to overlap windows - sparked a lawsuit from Apple that claimed Microsoft had appropriated the “look and feel” of their Macintosh operating system.

The irony there, of course, was that MacOS was modeled after the operating system used on the Xerox Alto a decade earlier.
Even while embroiled in legal battles both sides advanced their products. Microsoft had to because Windows 2 wasn’t any more popular than version 1.

DOS 4.0

Circa: 1988

DOS 4.0 was an evolutionary change to the operating system in most regards but the addition of mouse support at the DOS level allowed for “graphical” DOS shells to rival the earliest versions of Windows.

MacOS 6.x

Circa: 1988

System 6 introduced support for the Motorola 68030 processor used in later Mac IIs as well as the new 1.44MB 3.5” floppy drives that came with those new machines. System 6 evolved over the course of several years with maintenance releases and minor feature and product support additions through version 6.0.8.

Application Spotlight: Internet Browsers

Circa: 1989

In 1989 Tim Berners-Lee, working for CERN (European Laboratory for Particle Physics) in Geneva, Switzerland invented the Hypertext Markup Language (HTML) as a way of assisting particle physicists with document sharing and collaboration. He also built a prototype browser on the NeXT computer that was in common use at research institutions at that time.

By 1993 the NCSA (National Center for Supercomputer Applications) had built a new, more robust browser called Mosaic for Macs and IBM PCs running Windows.

Shortly thereafter Marc Andreessen, a major contributor to the development of NCSA Mosaic, joined forces with Jim Clark who had made his fortune founding Silicon Graphics. The two created Netscape Communications and the Netscape browser which quickly became the dominant player after its release in 1994.

Not content to let someone else’s browser run on their operating system Microsoft started work on Internet Explorer which was bundled with Windows 95.

A relatively brief but furious browser war ensued with Microsoft’s Internet Explorer ultimately prevailing over Netscape which was ultimately gobbled up by AOL in 1998.

IE has been the dominant player ever since but recent competitors in FireFox, Safari, Chrome and others have Microsoft back on the defensive.

Windows 3

Circa: 1990

Microsoft finally had a hit with Windows 3.0; although it took nearly a decade to get there. The new Operating System was still an extension of DOS but once launched it could run in 386 enhanced memory mode (older chips were still supported in lesser modes) and delivered performance and memory access that DOS couldn’t muster.

Microsoft eventually released Windows 3.1 which added multimedia support and other features to the OS. Version 3.11 – Windows for Workgroups –enhanced the networking infrastructure of Windows.

MacOS 7.x

Circa: 1991

OS 7 was a substantial upgrade to prior versions of MacOS introducing a new UI as well as support for the Motorola 68040 processor.

Later iterations supported the new PowerPC processors that took over for the 68000 line. Probably most significant was the introduction of 32-bit memory addressing which allowed for the ever growing RAM requirements of these new Macs but which also rendered many legacy applications non-functional.


Circa: 1991

This version of DOS started to address memory issues that were becoming obvious carryovers from legacy systems. The PC architecture, built around the 8088 microprocessor, was originally designed for 1MB of system RAM. With the advent of later generation chips (80286, 80386 and so on) the PC could address much more RAM, but DOS could not.

DOS 5 allowed the migration of the command shell into high memory to give the user that much more breathing room in the lower 640K allocated to them.

Game Spotlight: Castle Wolfenstein/Wolfenstein 3D

Circa: 1980/1992

In 1980 Muse Software released a game in which the player snuck into a Nazi controlled castle to steal war plans.
Inspired by that game, ID Software created and popularized a new genre: the First Person Shooter.

In the 1992 release of Wolf 3D the player looked out over their character’s hands, saw what he was seeing and shot what he was pointing at.

Of course, the enemy shot back, so the game was fast-paced and exciting. Wolf 3D was followed quickly by DOOM, QUAKE and a wide variety of other FPS games with ever increasing technology and realism.

Erik Klein wrote our Classic PC retrospective in our August issue. You can find his website at

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