A Critical History of Computer Graphics and Animation

In 1975 the researchers at Xerox PARC (Palo Alto Research Center) moved into their permanent headquarters at 3333 Coyote Hill Road near Stanford University in Palo Alto, California. Jacob Goldman had founded PARC just five years previous, and already at this early date the research team had developed many of the ideas that shaped the future of computing.

The Palo Alto Research Center's mission as directed by Xerox management was to create the office of the future. To that end they created many of the technologies we take for granted in the modern office, such as networked personal computers, with E-Mail, word processing, and laser printing, but the most significant innovation at PARC was the graphical user interface (GUI), the desktop metaphor that is so prevalent in modern personal computing today.

The GUI would make computer graphics an everyday part of the working environment. No longer would the display be simply lines of code and commands, it would be graphical with a true representation of typefaces and images. The bitmapped GUI display would help promote the concept of WYSIWYG (what you see is what you get) allowing people to laser print exactly what they saw on the screen.

In workstations of the past, graphics and commands where split between three different screens, a vector device for line graphics, a text display for entering commands, and a video / raster graphics screen coupled with a frame buffer to display the final rendered result. Xerox PARC combined these separate technologies into one raster graphics screen along with an easier way of issuing commands: the pop up menus, icons, and desktop metaphor of the graphical user interface. While mainline computer engineers scoffed at the idea of one computer for each person, the Xerox team built the Alto personal computer. Traditional computer applications centered on number and data manipulation; the Xerox team focused on words, design and communications.

The researcher roster at PARC reads like a who's who of the CGI world. As with many other areas of computer graphics, researchers from the University of Utah would play a key role in the development of the GUI and other products developed at PARC. The idea for GUI was actually first developed by Alan Kay from the University of Utah who went to work at PARC on the Alto project in 1970. Kay and Ed Cheadle built a computer called FLEX at the University of Utah between 1967 and 1969 that included the rudimentary elements of a GUI, including multiple tiled windows and square icons representing data and programs.

The first GUIs tried at Xerox PARC were very difficult to work with and depended too much on the processor to re-draw each bit when moving overlapping windows around. In 1974 a PARC researcher named Dan Ingalls , who was one of the principle architects of the Smalltalk object oriented language, invented a procedure for the movement of whole blocks of bits on the screen called "Bit Blit", or BitBLT. This display algorithm allowed overlapping windows to be quickly shuffled around the screen without overtaxing the processor.

The Xerox Star was the first commercial personal computer to use the now common desktop metaphor. David Smith, developer of the Star interface, said in a 1982 article

Every user's initial view of the Star is the Desktop, which resembles the top of an office desk, together with surrounding furniture and equipment. It represents a working environment, where projects and accessible resources reside. On the screen are displayed pictures of familiar office objects, such as documents, folders, file drawers, in-baskets, and out-baskets. These objects are displayed as small pictures, or icons.

PARC was initially divided into three units: the Computer Science Lab (CSL), the Systems Science Lab (SSL), and the General Science Lab (GSL). The CSL, run by Bob Taylor, was most responsible for the development of the graphical user interface. Taylor had worked on the ARPAnet, (a distributed network of computers, the predecessor to the Internet) and brought the idea of networked computers to PARC.

By 1979 there were hundreds of Altos networked together with more traffic and 'nodes' than the entire ARPAnet. Xerox PARC even had the world's first computer virus called a 'tapeworm' because it would eat it's way through the Ethernet and consume all available resources. Like many of PARC's innovations networking was ahead of it's time, and would not be widely available in personal computers for another decade.

In 1979, Xerox decided against marketing the Alto system. By then the organization barely resembled the buoyant company that a decade earlier had challenged both IBM and the office of the future. External factors including fierce competition, government antagonism, and economic recession all marked Xerox's slide from overconfidence to loss of confidence. Internal forces were even more combustible, as the company's research, finance, and marketing groups each pursued a separate vision of the "right" Xerox future. In the end, the company that invented the first version of the personal computing future found itself struggling to recapture the advantages of its copier past.

Alto had the ability to show other computers on the network as icons on it's graphical desktop. Much later Macintosh acquired this ability. With the birth of the Internet and the World Wide Web, computers could network to others across the world, but this was done with a separate application that was at first nongraphical (telnet, text-based FTP software). Later applications for accessing the internet became more GUI-like but were not part of the operating system (TurboGopher, Fetch, Anarchie). With the introduction of the first graphical web browser, Mosaic, in 1993 accessing the internet began to look more like a GUI.

With the release of Windows 95 and NT, Microsoft attempted to blur the distinction of the web browser application and operating system by bundling 95 with Internet Explorer. The windows and interface of Windows 95 could be set so that browsing the local computer looked almost the same as browsing the Internet. Microsoft got into legal trouble because the bundling strategy was seen as an attempt to block competition from Netscape and other browsers. (See Note 1 below)

John Warnock (University of Utah) helped develop Interpress and other printing and page description systems at PARC which allowed the Alto to become the first WYSIWYG computer when coupled with Xerox's laser printer. Later Warnock founded Adobe Systems which along with Apple computer helped bring about the desktop publishing revolution of the late 1980s . The combination of the Macintosh, the LaserWriter, and Adobe's page description software would forever change the world of publishing, typesetting, and graphic design.

Larry Tesler at PARC, who would later be part of the Apple LISA development team, began work on Gypsy, the world's first user friendly word processing application using pop-up menus and icons in 1974. Gypsy was later to become the basis for Microsoft Word when it's co-creator Tim Mott and others at PARC went to work at Microsoft. Gypsy was essentially the world's first desktop publishing software with advanced features such as drawing and editing graphics within the same application as the word processor. These features have only recently begun to emerge in software packages such as Adobe InDesign and QuarkXpress.

It is widely believed that the Xerox corporate management never realized what they had at PARC - it seems that they never shared the same vision as the researchers. The innovations developed there where never marketed successfully under the Xerox name. It took outside companies to market PARC innovations in GUI and WYSIWYG to make them the standards they are today.

Click on the images below to view a larger version (when available).

"The basic purpose of Xerox Corporation is to find the best means to bring greater order and discipline to information. Thus, our fundamental thrust, our common denominator, has evolved towards establishing leadership in what we call 'the architecture of information'. What we seek is to think of information itself as a natural and undeveloped environment which can be enclosed and made more habitable for the people who live and work within it. "
C. Peter McCulough
CEO Xerox Corporation

GUI
[g(raphical) u(ser) i(nterface)]
An interface for issuing commands to a computer utilizing a pointing device, such as a mouse, that manipulates and activates graphical images on a monitor.
Source: The American Heritage® Dictionary of the English Language, Fourth Edition

Marcin Wichary's excellent collection of GUI material - GUIdebook: Graphical User Interface Gallery

Xerox Star

1972: Xerox PARC and the Alto
http://www.cnn.com/TECH/computing/9907/08/1972.idg/

PARC history
http://www.parc.xerox.com/history.html

The Graphical User Interface
http://www.sitepoint.com/article/real-history-gui

PARC contributions have resulted in a plethora of products and other research results
(source unknown)

"Office automation has emerged as a full-blown systems approach that will revolutionize how offices work."
Business Week June 1975

To view the timeline of GUI contributions, click here.

To see a listing of the major research activities of Xerox PARC, click here.

A few miles down the road from Palo Alto was a man ready to share the vision of the PARC researchers. At the height of Apple Computer's early success in December 1979, Steve Jobs, then all of 24, had a privileged invitation to visit Xerox PARC. Jobs and engineers from Apple visited Xerox PARC and were given demonstrations of the Alto and it's graphical user interface. They would later incorporate much of what they saw into the design of the Lisa and Macintosh. Bill Atkinson and the architects of Lisa had begun working on a GUI before the demonstration at PARC, but it was far more static than what showed on the Alto.

In January 1983, Apple Computer officially unveiled the Lisa.  It featured a 5-MHz 68000 microprocessor, 1MB RAM, 2MB ROM, a 12-inch B/W monitor, 720x364 graphics, dual 5.25-inch 860KB floppy drives, and a 5MB Profile hard drive. It was slow, but innovative. Its initial price was $10,000.  "Lisa" stands for Local Integrated Software Architecture.

The original Lisa interface was less reliant on the mouse, it used a 'softkey' as it's primary pointing device, which was essentially arrow keys on the keyboard. The demo gave those at Apple devoted to a more dynamic GUI for the Lisa and Macintosh the proof they needed that the graphical desktop was the direction to head. Atkinson recalls that "mostly what we got was inspiration from the demo, and a bolstering of our convictions that a more graphical way to do things would make a business computer more accessible." Steve Jobs liked what PARC had done with the GUI so much that he convinced Larry Tesler to switch to Apple and help him develop the interface for the Lisa.

The Apple Lisa did not sell well because, like the Xerox STAR, it was too expensive ($10,000) as compared to IBM PCs of the day. Macintosh was the first personal computer with a GUI to be marketed successfully because of it's more reasonable price and well planned advertising strategy. At first the Mac did not sell as well as expected, because of it's lack of software; MacPaint and MacWrite were not enough for businesses who needed spread sheets and accounting software.

"They showed me three things. One of the things they showed me was object-oriented programming. Another one they showed me was a networked computer system ... they had over a hundred Alto computers all networked using email etc. I didn't even see that. I was so blinded by the first thing they showed me which was the graphical user inter:face. I thought it was the best thing I'd ever seen in my life. Now remember it was very flawed, what we saw was incomplete, they'd done a bunch of things wrong. But we didn't know that at the time, but still though, the germ of the idea was there and they'd done it very well, Within you know, ten minutes, it was obvious to me that all computers would work like this some day."
Steve Jobs, Apple Computer
commenting on his visit to Xerox PARC.

The Apple Lisa desktop

Apple's famous "1984" Macintosh ad

At the 2004 MacWorld, Steve Jobs presented the ad again as part of his keynote speech. In this version, the hammer-wielding female was outfitted with an Apple t-shirt and an iPod. The remade ad can be seen by clicking here.

The hammer throwing athlete/actress is Anya Major, who also appeared as the Russion borderguard in Elton John's music video Nikita.

The following segment is from an article in PCworld online in honor of the 20th anniversary of the Mac.

Remembering 1984
But the Macintosh marketing memories begin for most of the pioneers with the "1984" ad that played during the Super Bowl the week of the Macintosh's launch. Crafted by Hollywood director Ridley Scott, it was dramatic and artsy--and, as several of the principals recall, it almost didn't run.
A preview of the ad was greeted with foot-stomping, whistling applause from the sales force at a fall meeting, several members of the original Macintosh marketing team say. But the Apple board of directors was much less impressed, and in fact ordered ad agency Chiat/Day to try to sell the Super Bowl advertising time spots. When the agency reported it couldn't unload the 60-second spot by the deadline, Apple's board suggested swapping in an Apple II advertisement--but none was suitable. So the board acquiesced, the spot ran--and the Mac made its mark on the advertising field as well as on the technology world. Today, the Super Bowl is often the showcase for innovative advertisements.
"At the next board meeting two weeks later, they summoned the senior members of the Macintosh team," Murray says. "We went into the board room, and they all stood up and applauded."
Although broadcast just once, the ad is still a marketing message for Apple. It was eventually preloaded on some Apple systems and is available for download. A slightly modified version opened the keynote of the MacWorld Expo in January, so the javelin-thrower is also wearing an IPod along with a T-shirt bearing the Macintosh logo.

The IBM PC was more popular with businesses than the Mac even though it didn't have a GUI. Bill Gates and Microsoft began developing useful applications for the Mac which helped increase sales. Microsoft's early partnership with Apple allowed them access to the Mac OS which led to the development of their own GUI, Windows 1.0. Microsoft saw the Mac OS as a threat to their non-graphical operating systems for IBM PCs, MS DOS and knew that they had to develop a GUI to compete.

Steve Jobs had quoted a saying of Picasso that "good artists borrow, but great artists steal" in describing what the Macintosh had got from Xerox PARC. Microsoft might say the same about what they got from Apple. Windows appeared to copy many of the same metaphors and icons as the Mac GUI with just the names changed, for example the Trash Can in Mac, became the Recycle Bin in Windows (and later the Dumpster in X-Windows for SGI Workstations).Windows became more popular not because it was better than the Mac OS, but because it was more open, and could run on millions of IBM PCs and Mac Clones. Apple never licensed the Mac OS to clone makers except for a brief period in the mid 1990s. This caused Apple to lose market share, but kept the quality of their product more consistent than with IBM clones. Windows had flaws because it was built on top of the non-GUI MS-DOS, and it would behave differently on each type of PC clone.

In 1986 Steve Jobs left Apple after disagreements with the board of directors and founded a new company called NeXT which would develop NeXTStep, a GUI for it's Unix based workstations in 1988. This became the first GUI to simulate a three-dimensional screen. Later when Steve Jobs returned to Apple, NeXTStep would merge with the Mac OS to create Mac Os X.

Around the same time as NeXTStep, in the late 1980s, other Unix workstation manufactures wanted a piece of the GUI action. In 1987 the X Windows System for Unix workstations became widely available. Around 1989 several Unix-based GUIs were introduced. These included Open Look, by AT&T and Sun Microsystems, and Motif for the Open Software Foundation by DEC and Hewlett-Packard. Motif's appearance is based on IBM's Presentation Manager, a rival GUI to MS Windows.

Although the Macintosh and the PC were two important personal computer contributors to the graphics area, they were certainly not the only personal computers that impacted the market. Atari, Tandy, and Commodore all developed computers that helped push the success of the home or personal computer revolution.Of these, from a graphics standpoint, arguably the most influential computer was the Amiga.

By the end of the 1970s, the Apple II, the Tandy TRS-80 (Trash-80), and the Atari computers were available on the market, and Commodore was marketing the PET, or Personal Electronic Transactor. They used 8-bit processors, like the MOS 6502 and the Zilog80. In each case, the graphics capabilities were primitive. For example, the Apple II video controller displayed 24 lines by 40 columns of upper-case-only text on the screen, with NTSC composite video output for display on a monitor, or on a TV set by way of an RF modulator. There needed to be better graphics capabilities for these products to be as successful as their potential showed.

Jay Miner started working at Atari in the late 1970s. He was instrumental in pushing the capabilities of the electronics by combining the necessary components into a single chip, known as the TIA, or Television Interface Adaptor. The TIA was to become the display hardware for the Atari 2600 game console, and was the forerunner to the chip set which was the basis of the Atari 8-bit family of home computers, known as ANTIC and GTIA.

In the early 1980s Jay, along with other Atari staffers, had become disillusioned with management and started a new company in Santa Clara, called Hi-Toro. They worked on a new 16-bit (Motorola 68000 based) game console. This project, which then was code-named Lorraine, resulted in a design that could be upgraded to a full-fledged computer. Commodore International assumed ownership of Hi-Toro. It was at this time that the video-game market was beginning to fail, so the new owners began changing Lorraine's design to become a home computer, the Amiga.

(See Note 2 below)

In June 1985 the first production of an Amiga, the A1000 began. It had 256K RAM, which was later updated to 512K as standard which was enormous for its time. It also had a previously unknown 4096 color palette, and had a 14MHz Motorola 68000 processor. It also allowed direct to video tape recording with its integrated composite video output connection. The Amiga 1000 could have been a serious competitor to IBM's PC, but Commodore focused it specifically for home use, primarily as a replacement for the Commodore 64.

In 1986 Amiga's engineers started to design the A2000. This was to be the replacement to the A1000, with a bigger box, more expansion capabilities and an updated OS.  The A2000 (and its cheaper version the A500) were released in 1987. The A500 had only one expansion slot and a single memory-upgrade slot, and became the single most popular Amiga ever.

For its time, the Amiga had some of the most impressive sound and graphics (through several coprocessors) available for the home user. It was also used for commercial entertainment production during the 1980s. Newtek marketed a special graphics rendering solution of the Amiga, called the Video Toaster.  (The Video Toaster was used to render the space ships in the first season of Babylon 5). NewTek also created the Lightwave 3D rendering program on the Amiga, which they eventually ported to the PC. The support of overscan, interlacing and genlocking capabilities, and the fact that the display timing was very close to broadcast standards (NTSC or PAL), made the Amiga the ideal computer for video purposes, and was used in many studios for digitizing video data (sometimes called frame-grabbing), subtitling and interactive video news.

The chipset which gave the Amiga its unique graphics features consisted of three custom chips, OCS, ECS and AGA, nicknamed Agnus, Daphne (Denise), and Paula (Portia). Daphne was basically a non-programmable chip responsible for transferring the raw bit data through a hybrid integrated circuit to the RGB port. Paula was a sound chip that allowed 4 channel hardware DMA driven stereo output.

Agnus took care of the multimedia capabilities, providing DMA for sound and graphics, handling memory, and performing video timing (PAL or NTSC versions). The video timings were deliberately chosen to make it possible to use the Amiga with common household TV sets, and the Amiga had output ports for monochrome video signal, and separate RGB monitor connections.

A newer version of Agnus (used in most of the A500 and A2000 computers) was called Fat Agnus. It could handle a full megabyte of RAM. (Super Agnus, an even more recent version was able to support 2 MB RAM, and was able to change between PAL and NTSC video signal timing.)

The basic resolution of an Amiga display (sometimes called LoRes for low resolution) was 320x200 by 60 Hz (NTSC timing), or 320x256 by 50 Hz (PAL timing). In these resolutions, it was able to display 2, 4, 8, 16 or 32 colors in a palette based manner simultaneously from 4096 colors (4 bit for each of the RGB components).

The number of colors on screen could also be increased:

• EHB, or Extended HalfBright - an additional bit plane was used to display 64 colors, but the second 32 colors were half the brightness of the first 32.
• HAM, or Hold-And-Modify, where six bit planes were used, but only 16 colors were defined by the palette; the remaining 48 "colors" described how to modify the previous pixel color.
• A special mode existed (mainly used for games) called dual playfield mode, where two screens of maximum 8 colors were behind each other. One of the colors in the front screen was disabled and changed to transparent (for pixels having this color the other screen is visible).

The Amiga included a hardware BitBLt co-processor, which was used to create and move several dozen additional objects in the bit map each frame time, saving and restoring the background as necessary.  The Blitter also provided hardware support for line drawing and polygon filling functions. The operating system, AmigaOS, was quite sophisticated, combining an elegant GUI like that of the Apple Macintosh with some of the flexibility of UNIX while retaining a simplicity that made maintenance rather easy. The Copper processor was a 3 instruction co-processor running in parallel with main CPU, allowing for the creation graphics effects with minimal CPU load and intervention.

TRS-80

Commodore PET

Original Amiga PC Developer prototype

Lorraine concept sketch ... click on the image to see more concept sketches.
(above 2 images courtesy of Secret Weapons of Commodore)

Amiga A500

Amiga A500

Amiga A2000

The first wire-wrapped Video Toaster was designed by NewTek engineer Brad Carvey, brother of Saturday Night Live's Dana Carvey. His character Garth in the Wayne's World comedy sketches and movies is based on his brother.

 

One of the first fully dedicated computer labs to studies in the arts was established at Ohio State University. For many years, the HAT (Hopkins Art and Technology) Lab exclusively used the Amiga platform.

Article from the IEEE Spectrum, Amiga: The Computer That Wouldn't Die

The following description of the Apple/PC developments is from the introductory chapter of a Masters thesis written by Lionel Smith:

Hewlett-Packard minicomputer electronics engineer and programmer, Steve Wozniak, had developed an interest in microcomputers through the Homebrew Computer Club. Wozniak, whose real forte was simplifying circuits by making components fulfill more than one function, proceeded to design a small computer with video-terminal capability around the Mostek 6502 microprocessor (because at $25 it was the only one he could afford).

Electronics engineer, and entrepreneur Steve Jobs, the son of a salesman, had, while working for Atari, engaged the talents of Wozniak in hardwiring the video game Breakout. Wozniak reduced the chip count to 44 (when normal chip counts for this type of game were 150-170).The design was too complex for Atari engineers to understand and a pre-production redesign was required. Wozniak's talent for minimalist design was a vital factor in product commercial viability by keeping construction costs down.

Demonstrations of Wozniak's microcomputer at the Homebrew Club quickly led to firm orders for production machines. Hewlett-Packard, having declined an interest in the microcomputer designed by their employee, gave Wozniak a legal release, opening the way for the formation of Apple Computer and sales of the Apple I.

Soon Jobs and Wozniak realized that what the world wanted was a personal computer that only required connecting to a domestic TV to be made ready for use, so Wozniak designed a successor.

The Apple II, also based on the Mostek 6502 microprocessor, scored immediate success with its color graphics and use of discs for data and program storage. The operating system, also supplied on disc, required loading into RAM during startup. Sales of this machine accelerated fast enough for third parties to become interested in developing hardware expansions and software.

The spreadsheet, as an aid to financial planning and what-if analysis was the concept of Dan Bricklin who first produced a demonstration version written in BASIC on an Apple II. It was with this demonstration that the use of the slash character to initiate a command first appeared, which became such a familiar feature of spreadsheet software including Lotus 1.2.3. Bricklin teamed up with Bob Frankston and created the Software Arts company to produce the full assembly language version, VisiCalc. The combination of VisiCalc and a disc system was so successful that many Apple IIs were sold into the business community, enhancing Apple's credibility. Indeed, IBM held up the announcement of the IBM PC until a VisiCalc conversion was ready.

Thus, in the early nineteen-eighties, there were two de-facto standards for personal computers; the S-100 bus–CP/M camp and the Apple following. There were many other proprietary machine architectures, each with a unique combination of microprocessor, bus, memory architecture and file system formats, and transfer of data between formats was all but impossible.

When the IBM Personal Computer (PC) was introduced in August 1981, little did the world suspect that a standard was being set, a standard which would continue to make its existence strongly felt as far into the future as 1994, and possibly beyond.

IBM brought their first PC to market in a little over thirteen months from inception. This was remarkable for a company whose project gestation period was usually measured in years. A major factor in the short development time was that IBM had taken the unprecedented step, for an industry giant noted for developing products which were proprietary through and through, of using existing hardware components from external vendors. The use of many design elements of IBM's earlier System/23 DataMaster was also a major factor in the speed of development and expansion cards for this system could be used in the new machine.

More remarkable was the adoption of an operating system from the relatively small Microsoft company, who also supplied a BASIC language interpreter. IBM also offered CP/M-86, a 16-bit version of the 8-bit CP/M from Gary Kildall's Digital Research. The first DOS was 86-DOS for S-100 computers upgraded with the Intel 8086 CPU. DOS-86 was produced by Seattle Computer Products, the rights of which were bought by Microsoft.

The well thought out synthesis of the best features from existing microcomputers and the close compatibility with CP/M systems ensured marketing success beyond even IBM's expectation. The non-proprietary nature of the PC system architecture encouraged many other manufactures to begin building compatibles. This development had far-reaching consequences for the way in which the personal computer industry developed.

Although the 8088 microprocessor operates at 16-bits internally, it communicates with other components of the PC over an 8-bit bus. The advantage of this design strategy was that DataMaster features and 8-bit logic chips, which were plentiful and cheap, could be used.

Accessing memory over an 8-bit bus caused a bottleneck. In 1983 IBM introduce the PC/XT which was also built around the 8-bit Intel 8088 microprocessor. The PC/XT used version 2.0 of PCDOS, which for the first time used a hierarchical filing system capable of dealing with the much larger capacity hard discs with which the XT could be equipped.

Meanwhile Apple had embarked on a new project, code named Lisa, to develop a new office computer. In search of funds, Apple's Steve Jobs approached Xerox, whereupon he and other members of the Lisa team visited Xerox's Palo Alto Research Center (PARC), where they were shown the Alto. The Apple team was so impressed with the Alto's sharp graphics, displaying a virtual desktop complete with usable documents and small on screen pictures called icons, they decided that the Lisa would be the Alto for the masses.The Apple team's enthusiasm and ideas so impressed Larry Tesler, a member of the Alto's design team that he joined Apple.

High resolution graphics demand fast microprocessors and ample RAM, both very expensive commodities in 1983, the resultant high unit price was the major factor in the Lisa's commercial failure. Undeterred, the Apple team carried on with development and launched a scaled down version in 1984 under the name Macintosh, based on the Motorola 68000 microprocessor.

The Macintosh with its WIMP based GUI and its lack of program modality was a revelation to a world used to a command line, or at best menu driven interface. The Macintosh was to have a profound effect on the future development of personal computers. The Mac, as it became known, with its GUI-fronted operating system was presumably what Byte's Editor in Chief had in mind when he wrote:

"I'd buy an operating system any day that takes a long time to run a given program but which makes me more productive by communicating with me in useful ways." (Morgan, 1981).

In 1984 IBM introduced the IBM PC/AT built around the new Intel 80286 16-bit microprocessor. The 80286 apart from being capable of faster throughput than previous models offered some advanced features. Amongst these were processing parallelism and hardware implemented task switching with program protection.

Unfortunately in maintaining backward compatibility with version 2, the new 3.0 version of PCDOS did not support either multitasking or multiuser environments. Thus, the AT was primarily used as a more efficient PC/XT and could still only make use of a maximum of 640k of user memory in 'real address mode'. Users wishing to take advantage of the possible 16 megabytes of memory, as well as the multitasking and multiuser capability were expected to wait for the forthcoming XENIX operating system.

A major architectural feature of the original PC was the use of an expansion bus equipped with connectors, or slots, to take adaptor cards for interfacing with peripherals in particular visual display units (VDUs) and hard drives. The expansion slot data width is one factor which determines how quickly data flows between the microprocessor and the peripheral. The original PC slots had an 8-bits wide data path increased to 16-bits on the AT to match the data width of the 80286. Both the 8-bit and the 16-bit bus specifications are known as the ISA.

Compatible makers continued to build enhanced versions of the PC for sale at competitive prices, introducing all manner of compatibility issues as a result. IBM when developing a 32-bit bus to suite the new 32-bit Intel 80386, and realizing that they had lost control of their architecture, produced MCA. MCA used many proprietary methods and components with which IBM hoped to defeat the compatible makers. The first systems with MCA were the PS/2 range, launched in 1987, this included models built around the 80386, 80286 and 8086. PC compatible manufacturers were allowed to use MCA architecture providing they paid IBM substantial royalties.

To avoid paying such royalties, a consortium of compatible makers, led by Compaq, responded by developing the 32-bit EISA bus which, apart from being faster and cheaper to implement, had the added advantage of maintaining compatibility with existing 8MHz ISA bus adaptors.

The launch of the Macintosh had focused the computer world's attention on the user interface and where Apple led many were soon to follow. Digital Research produced GEM which could run under CP/M-86 or TOS on the Atari ST, and Microsoft produced Windows for the PC, both of which incurred Apple's wrath for being to close to the look and feel of the Mac interface, Commodore having bought out a small company Amiga, launched a computer of that name using Intuition, as a GUI.

IBM with Microsoft produced a new 16-bit operating system OS/2 for the PS/2 range. OS/2 was designed to give a GUI, Presentation Manager, a head start by clearing away the 640k memory limitations of MS-Dos. Meanwhile the Unix camp were evolving their own many flavors of GUI such as Motif, DEC-windows, Open Look, Open Desktop and NextStep. Nextstep is the user interface developed to run under Unix on the Next Computer, the product Steve Jobs nurtured sometime after leaving Apple.

The move towards GUIs was generally welcomed by the computing fraternity, but there was one big drawback, especially for users of PC systems running MS-Dos. GUIs such as Windows, with their resolutions of 640 x 480 pixels or larger as opposed to the typical 24 lines of 80 characters, increased dramatically the amount of video traffic.

Furthermore, if ram is limited, large volumes of data need to be swapped out to disc frequently. When this is achieved over the 8Mhz ISA bus then systems can become sluggish and unresponsive, no matter how fast and capable the microprocessor.

With the introduction of the fast 80486 CPU, overcoming the ISA bus bottleneck became a high priority, especially where graphics adaptors and Windows, SCSI interfaces often used by CD-ROMS and scanners and hard drives were concerned. One answer appeared in the concept of the local bus, with which peripherals are connected directly to the CPU and/or ram. A number of manufacturers, including Compaq, Dell and Hewlett-Packard developed their own proprietary local bus systems which, although technically adequate, restricted adaptor choice to specifically designed cards.

The first widely adopted local bus standard was the 32-bit VESA local bus, (VLB or VL bus). This bus could be driven as fast as the clock of a 33Mhz processor, higher speeds requiring the implementation of wait states. The VLB has a maximum rated throughput of 128-132 mbs compared to the ISA bus maximum of 8Mbs. VESA is a voluntary standard which some manufacturers have only partially implemented and it is in the process of being updated to cope with the 64-bit wide data path of the Pentium CPU.

PCI is an Intel initiated local bus standard which has been slow to gain wide acceptance because of its late introduction. With the increasing numbers of Pentium based systems PCI is becoming more widely accepted.

Many of these more recent bus technologies overcome the DMA and IRQ configuration troubles which continue to dog the majority of systems which still use the ISA bus. Many of these problems will not disappear until Windows dispenses with the services of the archaic DOS operating system:

"The 640KB of RAM that once seemed so luxurious is now choked with contentious device drivers and TSR programs. IRQs (interrupt requests), DMA channels, I/O memory ports, and other system resources are now being fought over like the last pebbles of ore in a played-out gold mine". (Halfhill, 1994)

Adaptor card timing problems can also cause much slot swapping and a rapidly growing collection of mutually exclusive cards.

The Apple Macintosh and the Acorn 32-bit RISC computers do not suffer from any such problems: the systems were designed from the ground-up with a more efficient and extensible combined operating system and GUI.

The first Macintosh had no network capabilities, and when asked about it, Steve Jobs reportedly threw a floppy disc at a journalist, saying "Here's my network".

Notes:

1. From the Tech Republic, June 24, 2003 —

Microsoft's settlement: The end of an era
By Tim Landgrave

Microsoft and AOL reached an agreement last week in which Microsoft paid AOL $750M and AOL agreed to use and interoperate with key Microsoft technologies. This agreement also signifies the end of a long battle between a startup and a software giant for control of the user interface for the Internet. I’ll look at the history of the Netscape vs. Microsoft battle and the implications for corporate planners now that Microsoft has emerged victorious.

The battle for the desktop
To the casual observer, the battle to become the de facto browser was about which piece of software would allow users to access Web sites. But to Netscape and Microsoft, it was much more than that. When Marc Andreeson and Jim Barksdale started Netscape in the early 90s, their initial goal was to create an easy-to-use interface that would allow computer users on any platform to access content on the Web. For the first few years, they had little or no competition. In fact, when Microsoft belatedly entered the browser market in 1995, its first incarnation of Internet Explorer was nothing more than a repackaged, down-level version of the same technology on which Netscape was based. Netscape had a clear lead in the market and was releasing new versions that allowed developers to take advantage of enhancements in HTML as soon as they were released.

Netscape also had a problem. Like many other Internet companies, it made the faulty assumption that you could give away technology to build a market and then generate revenues on usage through advertising or by creating other products on which your product depended. Although it created server-based products that worked with its browser and a branded portal (Netscape.com) through which it funneled users, it was never able to build a large enough revenue stream to make the browser a primary source of revenue.

As Netscape became not only the dominant Windows browser but also the dominant cross-platform browser, the company began planning to extend its model to become more than just the browser. In fact, Marc Andreeson made the bold prediction that one day Netscape would replace Windows as the default user interface. His prediction wasn’t far off. If Netscape could run on all platforms and all applications became Web applications, Windows would be irrelevant. In fact, Netscape could become the default shell for any operating system including Windows and any derivative of UNIX. Unfortunately for Netscape, Microsoft came to the same conclusion.

Why Microsoft won the battle
When faced with the prospect of a major competitor becoming the default UI shell for its customers, Microsoft had to respond and do so quickly. If Netscape’s position was to make the operating system irrelevant, Microsoft’s position was to make the browser irrelevant. Making the browser “just another operating system feature” involved creating tight ties between the browser and the operating system. But since Microsoft could only create these ties for its own operating systems, one of the first things it had to do was stop releasing versions of IE for other platforms.

Next, it created mechanisms for the OS and the browser to interact at a more direct level. To users, these features became known as ActiveX features. With the Active Desktop, users could place views of Web sites (news, weather, or internal sites) on their desktops and navigate the desktop like a browser. ActiveX controls allowed developers to create rich Web applications which downloaded controls that could use OS features directly, giving them a richer surface to program against than the sandboxed Java client controls.

But this richness came with a price. It meant that the security of the desktop could easily be compromised with versions of the OS that had no differentiation between the permissions granted to code loading locally with the user’s permissions vs. code loading from external sources that should be granted more restrictive permissions. It's security issues like these that have plagued Microsoft's operating systems for years. But in spite of these security issues, it was the ability to create a richer user experience by integrating the browser into the operating system that led AOL to come to the conclusion that it needed to use this technology for its online service customers. What makes this conclusion even more startling is that AOL acquired Netscape a few years ago in hopes of making it its key browser technology.

Corporate aftershocks
The AOL decision will send aftershocks through many corporations. Although corporate use of Netscape has gone from a high of 90 percent in its heyday to less than 10 percent today, the view of the browser as a separate piece of software has never really changed. Companies have been reluctant to build software that relied on features specific to IE even if it meant they could build richer software. They were concerned about the ability for external users to access their sites if they used IE-specific features. With AOL moving to IE wholesale, corporate developers now have a richer canvas on which to create their applications.

This suit also clears Microsoft’s final impediment to finally making IE a first-class feature of the operating system rather than an add-on. The only significant desktop-based legal hurdle for Microsoft is the two states that didn’t sign on to the Justice Department settlement, but it’s unlikely they’ll be able to overturn the federal government’s settlement. This means that Microsoft has been cleared to make IE the browser of choice for Windows computing. Ironically, it also means that Microsoft will probably stop considering it a different product and simply start releasing it as part of a new operating system release. Why? Because the only way to eliminate the inherent security flaws in a browser tied to the operating system is to replace it with browser technology that’s integrated into the fabric of the operating system, including its security mechanisms.

Although we may see an interim release before Longhorn, after Longhorn, I don’t expect to see any future releases of standalone IE for prior versions of Microsoft Windows. (In fact, a Microsoft product manager has already admitted as much.)

The end of the AOL suit also means that Windows Media Player will become the default audio and video player and its Digital Rights Management features will allow corporations to distribute these media assets with confidence that their copyrights can be protected. And I think we’ll finally see real interoperability between AOL’s Instant Messaging and Microsoft Instant Messaging as a result of this settlement.

What about Netscape?
I believe that Netscape’s future will be as the default Linux browser. Although other browsers like Opera will continue to operate cross-platform, the logical future for Netscape is for the Linux community to embrace the Netscape Mozilla initiative and give their OS a rich browser experience based on that code base. Unless corporations move en masse to Linux desktops, the Netscape browser technology will go down in the history books as another failed attempt to wrest control of the desktop from Microsoft.

2. Jack Tramiel invested $500,000 in the Amiga Lorraine project, hoping to use the results of their development for a series of 32-bit machines that would replace Atari's existing home computer line. As Amiga's financial health got worse, Commodore took over the entire Amiga staff and the Lorraine project, just before Tramiel could assume ownership. He subsequently sued Amiga for fraud in the matter of the development of the three VLSI chips, which Amiga alleged didn't work, canceling the deal. Tramiel felt that the chips did work, and were going to be part of a the new Commodore computer.

Thanks to graduate students John Buck, Jon Gladden and Lionel Smith for their contributions to this section.