How the Graphical User Interface Was Invented

Throughout the Seventies and early Nineteen Eighties, most of the early ideas for home windows, menus, icons, and mice have been arduously researched at Xerox Corp.’s Palo Alto Research Center (PARC), Palo Alto, Calif. In 1973, PARC developed the prototype Alto, the primary of two computer systems that may show seminal on this space. More than 1200 Altos have been constructed and examined. From the Alto’s ideas, beginning in 1975, Xerox’s System Development Department then developed the Star and launched it in 1981—the primary such user-friendly machine offered to the general public.

In 1984, the low-cost Macintosh from Apple Computer Inc., Cupertino, Calif., introduced the pleasant interface to 1000’s of private laptop customers. During the following 5 years, the worth of RAM chips fell sufficient to accommodate the large reminiscence calls for of bit-mapped graphics, and the Mac was adopted by dozens of comparable interfaces for PCs and workstations of all types. By now, utility programmers have gotten conversant in the concept of manipulating graphic objects.

The Mac’s success throughout the Nineteen Eighties spurred Apple Computer to pursue authorized motion over possession of many options of the graphical person interface. Suits now being litigated may assign these improvements to not the designers and their corporations, however to those that first filed for authorized safety on them.

The GUI began with Sketchpad

The grandfather of the graphical person interface was Sketchpad [see photograph]. Massachusetts Institute of Technology pupil Ivan E. Sutherland constructed it in 1962 as a Ph.D. thesis at MIT’s Lincoln Laboratory in Lexington, Mass. Sketchpad customers couldn’t solely draw factors, line segments, and round arcs on a cathode ray tube (CRT) with a lightweight pen—they may additionally assign constraints to, and relationships amongst, no matter they drew.

Arcs may have a specified diameter, traces may very well be horizontal or vertical, and figures may very well be constructed up from mixtures of components and shapes. Figures may very well be moved, copied, shrunk, expanded, and rotated, with their constraints (proven as onscreen icons) dynamically preserved. At a time when a CRT monitor was a novelty in itself, the concept that customers may interactively create objects by drawing on a pc was revolutionary.

Sketchpad, created in 1962 by Ivan Sutherland at Massachusetts Institute of Technology’s Lincoln Laboratory in Lexington, is taken into account the primary laptop with a windowing interface.

The Computer Museum

Moreover, to zoom in on objects, Sutherland wrote the primary window-drawing program, which required him to provide you with the primary clipping algorithm. Clipping is a software program routine that calculates which a part of a graphic object is to be displayed and shows solely that half on the display. The program should calculate the place a line is to be drawn, evaluate that place to the coordinates of the window in use, and stop the show of any line section whose coordinates fall outdoors the window.

Though movies of Sketchpad in operation have been extensively proven within the laptop analysis group, Sutherland says at the moment that there was little rapid fallout from the undertaking. Running on MIT’s TX-2 mainframe, it demanded an excessive amount of computing energy to be sensible for particular person use. Many different engineers, nevertheless, see Sketchpad’s design and algorithms as a major affect on a whole technology of analysis into person interfaces.

The origin of the pc mouse

The mild pens used to pick areas of the display by interactive laptop methods of the Fifties and Sixties—together with Sketchpad—had drawbacks. To do the pointing, the person’s arm needed to be lifted up from the desk, and after some time that acquired tiring. Picking up the pen required fumbling round on the desk or, if it had a holder, taking the time after making a range to place it again.

Sensing an object with a lightweight pen was easy: the pc displayed spots of sunshine on the display and interrogated the pen as as to whether it sensed a spot, so this system all the time knew simply what was being displayed. Locating the place of the pen on the display required extra refined methods—like displaying a cross sample of 9 factors on the display, then shifting the cross till it centered on the sunshine pen.

In 1964, Douglas Engelbart, a analysis undertaking chief at SRI International in Menlo Park, Calif., examined all of the commercially obtainable pointing gadgets, from the still-popular mild pen to a joystick and a Graphicon (a curve-tracing machine that used a pen mounted on the arm of a potentiometer). But he felt the choice did not cowl the total spectrum of attainable pointing gadgets, and one way or the other he ought to fill within the blanks.

Then he remembered a Forties faculty class he had taken that lined using a planimeter to calculate space. (A planimeter has two arms, with a wheel on every. The wheels can roll solely alongside their axes; when one in all them rolls, the opposite should slide.)

If a potentiometer have been hooked up to every wheel to watch its rotation, he thought, a planimeter may very well be used as a pointing machine. Engelbart defined his roughly sketched concept to engineer William English, who with the assistance of the SRI machine store constructed what they shortly dubbed “the mouse.”

This first mouse was large as a result of it used single-turn potentiometers: one rotation of the wheels needed to be scaled to maneuver a cursor from one facet of the display to the opposite. But it was easy to interface with the pc: the processor simply learn frequent samples of the potentiometer positioning indicators via analog-to-digital converters.

The cursor moved by the mouse was simple to find, since readings from the potentiometer decided the place of the cursor on the screen-unlike the sunshine pen. But programmers for later windowing methods discovered that the software program crucial to find out which object the mouse had chosen was extra complicated than that for the sunshine pen: they needed to evaluate the mouse’s place with that of all of the objects displayed onscreen.

The laptop mouse will get redesigned—and redesigned once more

Engelbart’s group at SRI ran managed experiments with mice and different pointing gadgets, and the mouse received arms down. People tailored to it shortly, it was simple to seize, and it stayed the place they put it. Still, Engelbart wished to tinker with it. After experimenting, his group had concluded that the correct ratio of cursor motion to mouse motion was about 2:1, however he wished to attempt various that ratio—lowering it at sluggish speeds and elevating it at quick speeds—to enhance person management of high quality actions and velocity up bigger actions. Some fashionable mouse-control software program incorporates this concept, together with that of the Macintosh.

The mouse, nonetheless experimental at this stage, didn’t change till 1971. Several members of Engelbart’s group had moved to the newly established PARC, the place many different researchers had seen the SRI mouse and the check report. They determined there was no must repeat the assessments; any experimental methods they designed would use mice.

Said English, “This was my second chance to build a mouse; it was obvious that it should be a lot smaller, and that it should be digital.” Chuck Thacker, then a member of the analysis workers, suggested PARC to rent inventor Jack Hawley to construct it.

Hawley determined the mouse ought to use shaft encoders, which measure place by a collection of pulses, as a substitute of potentiometers (each have been lined in Engelbart’s 1970 patent), to remove the costly analog-to-digital converters. The primary precept, of 1 wheel rolling whereas the opposite slid, was licensed from SRI.

The ball mouse was the “easiest patent I ever got. It took me five minutes to think of, half an hour to describe to the attorney, and I was done.”
—Ron Rider

In 1972, the mouse modified once more. Ron Rider, now vp of methods structure at PARC however then a brand new arrival, stated he was utilizing the wheel mouse whereas an engineer made excuses for its uneven operation (one wheel dragging whereas one turned). “I suggested that they turn a trackball upside down, make it small, and use it as a mouse instead,” Rider instructed IEEE Spectrum. This machine got here to be often known as the ball mouse. “Easiest patent I ever got,” Rider stated. “It took me five minutes to think of, half an hour to describe to the attorney, and I was done.”

In the PARC ball mouse design, the load of the mouse is transferred to the ball by a swivel machine and on one or two casters on the finish of the mouse farthest from the wire “tail.” A prototype was constructed by Xerox’s Electronics Division in El Segundo, Calif., then redesigned by Hawley. The rolling ball turned two perpendicular shafts, with a drum on the tip of every that was coated with alternating stripes of conductive and nonconductive materials. As the drum turned, the stripes transmitted electrical impulses via metallic wipers.

When Apple Computer determined in 1979 to design a mouse for its Lisa laptop, the design mutated but once more. Instead of a metallic ball held in opposition to the substrate by a swivel, Apple used a rubber ball whose traction trusted the friction of the rubber and the load of the ball itself. Simple pads on the underside of the case carried the load, and optical scanners detected the movement of the inner wheels. The machine had free tolerances and few shifting components, in order that it value maybe 1 / 4 as a lot to construct as earlier ball mice.

How the pc mouse gained and misplaced buttons

The first, wood, SRI mouse had just one button, to check the idea. The plastic batch of SRI mice unhealthy three side-by-side buttons—all there was room for, Engelbart stated. The first PARC mouse unhealthy a column of three buttons-again, as a result of that greatest match the mechanical design. Today, the Apple mouse has one button, whereas the remaining have two or three. The situation is not 1950—an ordinary 6-by-10-cm mouse may now have dozens of buttons—however human components, and the consultants have robust opinions.

Said English, now director of internationalization at Sun Microsystems Inc., Mountain View, Calif.: “Two or three buttons, that’s the debate. Apple made a bad choice when they used only one.” He sees two buttons because the minimal as a result of two capabilities are primary to choosing an object: pointing to its begin, then extending the movement to the tip of the item.

William Verplank, a human components specialist within the group that examined the graphical interface at Xerox from 1978 into the early Nineteen Eighties, concurred. He instructed Spectrum that with three buttons, Alto customers forgot which button did what. The group’s assessments confirmed that one button was additionally complicated, as a result of it required actions similar to double-clicking to pick after which open a file.

“We have agonizing videos of naive users struggling” with these issues, Verplank stated. They concluded that for many customers, two buttons (as used on the Star) are optimum, if a button means the identical factor in each utility. English experimented with one-button mice at PARC earlier than concluding they have been a nasty concept.

More than 1200 of the experimental Alto, developed in 1973 by the Xerox Palo Alto Research Center, have been distributed to check its home windows, menus, and mouse.

Xerox Corp.

But many interface designers dislike a number of buttons, saying that double-clicking a single button to pick an merchandise is simpler than remembering which button factors and which extends. Larry Tesler, previously a pc scientist at PARC, introduced the one-button mouse to Apple, the place he’s now vp of superior know-how. The firm’s rationale is that to draw novices to its computer systems one button was so simple as it may get.

More than two million one-button Apple mice at the moment are in use. The Xerox and Microsoft two-button mice are much less frequent than both Apple’s ubiquitous one-button mannequin or the three-button mice discovered on technical workstations. Dozens of corporations manufacture mice at the moment; most are barely smaller than a pack of cigarettes, with minor variations in form.

How home windows first got here to the pc display

In 1962, Sketchpad may cut up its display horizontally into two unbiased sections. One part may, for instance, give a close-up view of the item within the different part. Researchers name Sketchpad the primary instance of tiled home windows, that are laid out facet by facet. They differ from overlapping home windows, which will be stacked on high of one another, or overlaid, obscuring all or a part of the decrease layers.

Windows have been an apparent technique of including performance to a small display. In 1969, Engelbart outfitted NLS (because the On-Line System he invented at SRI throughout the Sixties was recognized, to tell apart it from the Off-Line System often known as FLS) with home windows. They cut up the display into a number of components horizontally or vertically, and launched cross-window enhancing with a mouse.

By 1972, led by researcher Alan Kay, the Smalltalk programming language group at Xerox PARC had carried out their model of home windows. They have been working with far totally different know-how from Sutherland or Engelbart: by deciding that their photos needed to be displayed as dots on the display, they led a transfer from vector to raster shows, to make it easy to map the assigned reminiscence location of every of these spots. This was the bit map invented at PARC, and made viable throughout the Nineteen Eighties by continuous efficiency enhancements in processor logic and reminiscence velocity.

Experimenting with bit-map manipulation, Smalltalk researcher Dan Ingalls developed the bit-block switch process, often known as BitBlt. The BitBlt software program enabled utility applications to combine and manipulate rectangular arrays of pixel values in on-screen or off-screen reminiscence, or between the 2, combining the pixel values and storing the consequence within the applicable bit-map location.

BitBlt made it a lot simpler to write down applications to scroll a window (transfer a picture via it), resize (enlarge or contract) it, and drag home windows (transfer them from one location to a different on display). It led Kay to create overlapping home windows. They have been quickly carried out by the Smalltalk group, however made clipping tougher.

Some researchers query whether or not overlapping home windows provide extra advantages than tiled on the grounds that screens with overlapping home windows grow to be so messy the person will get misplaced.

In a tiling system, defined researcher Peter Deutsch, who labored with the Smalltalk group, the clipping borders are merely horizontal or vertical traces from one display border to a different, and software program simply tracks the situation of these traces. But overlapping home windows might seem anyplace on the display, randomly obscuring bits and items of different home windows, in order that fairly irregular areas have to be clipped. Thus utility software program should continually observe which parts of their home windows stay seen.

Some researchers nonetheless query whether or not overlapping home windows provide extra advantages than tiled, not less than above a sure display measurement, on the grounds that screens with overlapping home windows grow to be so messy the person will get misplaced. Others argue that overlapping home windows extra intently match customers’ work patterns, since nobody arranges the papers on their bodily desktop in neat horizontal and vertical rows. Among software program engineers, nevertheless, overlapping home windows appear to have received for the person interface world.

So has the cut-and-paste enhancing mannequin that Larry Tesler developed, first for the Gypsy textual content editor he wrote at PARC and later for Apple. Charles Irby—who labored on Xerox’s home windows and is now vp of improvement at Metaphor Computer Systems Inc., Mountain View, Calif.—famous, nevertheless, that cut-and-paste labored higher for pure text-editing than for shifting graphic objects from one utility to a different.

The origin of the pc menu bar

Menus—capabilities repeatedly listed onscreen that may very well be referred to as into motion with key mixtures—have been generally utilized in protection computing by the Sixties. But it was solely with the arrival of BitBlt and home windows that menus may very well be made to seem as wanted and to vanish after use. Combined with a pointing machine to point a person’s choice, they’re now an integral a part of the user-friendly interface: customers not must check with manuals or memorize obtainable choices.

Instead, the alternatives will be referred to as up at a second’s discover each time wanted. And menu design has developed. Some new methods use nested hierarchies of menus; others provide totally different menu variations—one with essentially the most generally used instructions for novices, one other with all obtainable instructions for the skilled person.

Among the primary to check menus on demand was PARC researcher William Newman, in a program referred to as Markup. Hard on his heels, the Smalltalk group inbuilt pop-up menus that appeared on display on the cursor web site when the person pressed one of many mouse buttons.

Implementation was on the entire easy, recalled Deutsch. The one exception was figuring out whether or not the menu or the applying ought to maintain observe of the knowledge quickly obscured by the menu. In the Smalltalk 76 model, the popup menu saved and restored the display bits it overwrote. But in at the moment’s multitasking methods, that may not work, as a result of an utility might change these bits with out the menu’s data. Such methods add one other layer to the working system: a show supervisor that tracks what’s written the place.

The manufacturing Xerox Star, in 1981, featured an extra advance: a menu bar, primarily a row of phrases indicating obtainable menus that may very well be popped up for every window. Human components engineer Verplank recalled that the bar was at first situated on the backside of its window. But the Star crew discovered customers have been extra more likely to affiliate a bar with the window under it, so it was moved to the highest of its window.

Apple simplified issues in its Lisa and Macintosh with a single bar positioned on the high of the display. This menu bar relates solely to the window in use: the menus may very well be ‘‘pulled down” from the bar, to appear below it. Designer William D. Atkinson received a patent (assigned to Apple Computer) in August 1984 for this innovation.

One new addition that most user interface pioneers consider an advantage is the tear-off menu, which the user can move to a convenient spot on the screen and “pin” there, always visible for ready access.

Many windowing interfaces now offer command-key or keyboard alternatives for many commands as well. This return to the earliest of user interfaces—key combinations—neatly supplements menus, providing both ease of use for novices and for the less experienced, and speed for those who can type faster than they can point to a menu and click on a selection.

How the computer “icon” got its name

Sketchpad had on-screen graphic objects that represented constraints (for example, a rule that lines be the same length), and the Flex machine built in 1967 at the University of Utah by students Alan Kay and Ed Cheadle had squares that represented programs and data (like today’s laptop “folders”). Early work on icons was additionally accomplished by Bell Northern Research, Ottawa, Canada, stemming from efforts to switch the just lately legislated bilingual indicators with graphic symbols.

But the idea of the pc “icon” was not formalized till 1975. David Canfield Smith, a pc science graduate pupil at Stanford University in California, started work on his Ph.D. thesis in 1973. His advisor was PARC’s Kay, who instructed that he have a look at utilizing the graphics energy of the experimental Alto not simply to show textual content, however fairly to assist individuals program.

David Canfield Smith took the time period icon from the Russian Orthodox church, the place an icon is greater than a picture, as a result of it embodies properties of what it represents.

Smith took the time period icon from the Russian Orthodox church, the place an icon is greater than a picture, as a result of it embodies properties of what it represents: a Russian icon of a saint is holy and is to be commemorated. Smith’s laptop icons contained all of the properties of the applications and information represented, and due to this fact may very well be linked or acted on as in the event that they have been the actual factor.

After receiving his Ph.D. in 1975, Smith joined Xerox in 1976 to work on Star improvement. The very first thing he did, he stated, was to recast his idea of icons in workplace phrases. “I looked around my office and saw papers, folders, file cabinets, a telephone, and bookshelves, and it was an easy translation to icons,” he stated.

Xerox researchers developed, examined, and revised icons for the Star interface for 3 years earlier than the primary model was full. At first they tried to make the icons appear to be an in depth photographic rendering of the item, recalled Irby, who labored on testing and refining the Xerox home windows. Trading off label area, legibility, and the variety of icons that match on the display, they determined to constrain icons to a 1-inch (2.5-centimeter) sq. of 64 by 64 pixels, or 512 eight-bit bytes.

Then, Verplank recollects, they found that due to a background sample primarily based on two-pixel dots, the right-hand facet of the icons appeared jagged. So they elevated the width of the icons to 65 pixels, regardless of an outcry from programmers who appreciated the neat 16-bit breakdown. But the rise caught, Verplank stated, as a result of that they had already determined to retailer 72 bits per facet to permit for white area round every icon.

After deciding on a measurement for the icons, the Star builders examined 4 units developed by two graphic designers and two software program engineers. They found that, for instance, resizing might trigger issues. They shrunk the icon for an individual—a head and shoulders—with the intention to use a number of of them to signify a bunch, solely to listen to one check topic say the display decision made the lowered icon appear to be a cross above a tombstone. Computer graphics artist Norm Cox, now of Cox & Hall, Dallas, Texas, was lastly employed to revamp the icons.

Icon designers at the moment nonetheless wrestle with the necessity to make icons adaptable to the numerous totally different system configurations supplied by laptop makers. Artist Karen Elliott, who has designed icons for Microsoft, Apple, Hewlett-Packard Co., and others, famous that on totally different methods an icon could also be displayed in numerous colours, a number of resolutions, and quite a lot of grey shades, and it might even be inverted (mild and darkish areas reversed).

In the previous few years, one other concern has been added to icon designers’ duties: internationalization. Icons designed within the United States usually lack area for translations into languages apart from English. Elliott due to this fact tries to depart area for each the longer phrases and the vertical orientation of some languages.

More than two million of the Apple Macintosh (high), which introduced the graphical person interface to non-public computer systems, have been offered. Much of its utility software program is inconsistent, nevertheless: not less than three totally different icons (backside) can signify handle recordsdata. The icons are present in Desktop Express from Dow Jones & Co., HyperCard from Apple Computer Inc., and MS Word from Microsoft Corp.

Apple Computer Inc.

The primary rule is to make icons easy, clear, and simply recognizable. Discarded objects are positioned in a trash can on the Macintosh. On the NeXT Computer System, from NeXT Inc., Palo Alto, Calif.—the corporate shaped by Apple cofounder Steven Jobs after he left Apple—they’re dumped right into a Black Hole. Elliott sees NeXT’s black gap as among the finest icons ever designed: ”It is distinct; its roundness stands out from the opposite, sq. icons, and that is essential on a crowded show. It matches my picture of data being sucked away, and it makes it clear that dumping one thing is severe.

English disagrees vehemently. The black gap “is fundamentally wrong,” he stated. “You can dig paper out of a wastebasket, but you can’t dig it out of a black hole.” Another critic referred to as the black gap acquainted solely to “computer nerds who read mostly science fiction and comics,” to not basic customers.

With the introduction of the Xerox Star in June 1981, the graphical person interface, as it’s recognized at the moment, arrived available on the market. Though not a industrial triumph, the Star generated nice curiosity amongst laptop customers, because the Alto earlier than it had throughout the universe of laptop designers.

Even earlier than the Star was launched, Jobs, then nonetheless at Apple, had visited Xerox PARC in November 1979 and requested the Smalltalk researchers dozens of questions concerning the Alto’s inner design. He later recruited Larry Tesler from Xerox to design the person interface of the Apple Lisa.

With the Lisa after which the Macintosh, launched in January 1983 and January 1984 respectively, the graphical person interface reached the low-cost, high-volume laptop market.

At nearly $10,000, patrons deemed the Lisa too costly for the workplace market. But aided by prizewinning promoting and its cheaper price, the Macintosh took the world by storm. Early Macs had solely 128K bytes of RAM, which made them sluggish to reply as a result of it was too little reminiscence for heavy graphic manipulation. Also, the time wanted for programmers to be taught its Toolbox of graphics routines delayed utility packages till nicely into 1985. But the Mac’s ease of use was indeniable, and it generated curiosity that spilled over into the MS-DOS world of IBM PCs and clones, in addition to Unix-based workstations.

Who owns the graphical person interface?

The widespread acceptance of such interfaces, nevertheless, has led to bitter lawsuits to ascertain precisely who owns what. So far, none of a number of litigious corporations has definitively established that it owns the software program that implements home windows, icons, or early variations of menus. But the fits proceed.

Virtually all the businesses that make and promote both wheel or ball mice paid license charges to SRI or to Xerox for his or her patents. Engelbart recalled that SRI patent attorneys inspected all of the early work on the interface, however understood solely {hardware}. After taking a look at developments just like the implementation of home windows, they instructed him that none of it was patentable.

At Xerox, the Star improvement crew proposed 12 patents having to do with the person interface. The firm’s patent committee rejected all however two on {hardware}—one on BitBlt, the opposite on the Star structure. At the time, Charles Irby stated, it was a great choice. Patenting required full disclosure, and no precedents then existed for profitable software program patent fits.

The most up-to-date and most publicized go well with was filed in March 1988, by Apple, in opposition to each Microsoft and Hewlett-Packard Co., Palo Alto, Calif. Apple alleges that HP’s New Wave interface, requiring model 2.03 of Microsoft’s Windows program, embodies the copyrighted “audio visual computer display” of the Macintosh with out permission; that the shows of Windows 2.03 are unlawful copies of the Mac’s audiovisual works; and that Windows 2.03 additionally exceeds the rights granted in a November 198S settlement wherein Microsoft acknowledged that the shows in Windows 1.0 have been derivatives of these in Apple’s Lisa and Mac.

In March 1989, U.S. District Judge William W. Schwarzer dominated Microsoft had exceeded the bounds of its license in creating Windows 2.03. Then in July 1989 Schwarzer dominated that every one however 11 of the 260 gadgets that Apple cited in its go well with have been, actually, acceptable beneath the 1985 settlement. The bigger situation—whether or not Apple’s copyrights are legitimate, and whether or not Microsoft and HP infringed on them—won’t now be examined till 1990.

Among these 11 are overlapping home windows and movable icons. According to Pamela Samuelson, a famous software program mental property knowledgeable and visiting professor at Emory University Law School, Atlanta, Ga., many consultants would regard each as useful options of an interface that can not be copyrighted, fairly than “expressions” of an concept protectable by copyright.

But attorneys for Apple—and for different corporations which have filed lawsuits to guard the “appear and feel’’ of their display shows—preserve that if such safety will not be granted, corporations will lose the financial incentive to market technological improvements. How is Apple to guard its funding in growing the Lisa and Macintosh, they argue, if it can’t license its improvements to corporations that wish to make the most of them?

If the Apple-Microsoft case does go to trial on the copyright points, Samuelson stated, the courtroom might have to think about whether or not Apple can assert copyright safety for overlapping windows-an interface characteristic on which patents have additionally been granted. In April 1989, for instance, Quarterdeck Office Systems Inc., Santa Monica, Calif., obtained a patent for a a number of windowing system in its Desq system software program, launched in 1984.

Adding gas to the authorized fireplace, Xerox stated in May 1989 it could ask for license charges from corporations that use the graphical person interface. But it’s unclear whether or not Xerox has an ample declare to both copyright or patent safety for the early graphical interface work accomplished at PARC. Xerox did receive design patents on later icons, famous human components engineer Verplank. Meanwhile, each Metaphor and Sun Microsystems have negotiated licenses with Xerox for their very own interfaces.

To Probe Further

The September 1989 IEEE Computer incorporates an article, “The Xerox ‘Star’: A Retrospective,” by Jeff Johnson et al., masking improvement of the Star. “Designing the Star User Interface,’’ [PDF] by David C. Smith et al., appeared within the April 1982 situation of Byte.

The Sept. 12, 1989, PC Magazine incorporates six articles on graphical person interfaces for private computer systems and workstations. The July 1989 Byte consists of ‘‘A Guide to [Graphical User Interfaces),” by Frank Hayes and Nick Baran, which describes 12 current interfaces for workstations and personal computers. “The Interface of Tomorrow, Today,’’ by Howard Reingold, in the July 10, 1989, InfoWorld does the same. “The interface that launched a thousand imitations,” by Richard Rawles, in the March 21, 1989, MacWeek covers the Macintosh interface.

The human factors of user interface design are discussed in The Psychology of Everyday Things, by Donald A. Norman (Basic Books Inc., New York, 1988). The January 1989 IEEE Software contains several articles on methods, techniques, and tools for designing and implementing graphical interfaces. The Way Things Work, by David Macaulay (Houghton Mifflin Co., Boston, 1988), contains a detailed drawing of a ball mouse.

The October 1985 IEEE Spectrum covered Xerox PARC’s history in “Research at Xerox PARC: a founder’s assessment,” by George Pake (pp. 54-61) and “Inside the PARC: the ‘information architects,’“ by Tekla Perry and Paul Wallich (pp. 62-75).

William Atkinson received patent no. 4,464,652 for the pulldown menu system on Aug. 8, 1984, and assigned it to Apple. Gary Pope received patent no. 4,823,108, for an improved system for displaying images in “windows” on a computer screen, on April 18, 1989, and assigned it to Quarterdeck Office Systems.

The wheel mouse patent, no. 3,541,541, “X-Y position indicator for a display system,” was issued to Douglas Engelbart on Nov. 17, 1970, and assigned to SRI International. The ball mouse patent, no. 3,835,464, was issued to Ronald Rider on Sept. 10, 1974, and assigned to Xerox.

The first selection device tests to include a mouse are covered in “Display-Selection Techniques for Text Manipulation,” by William English, Douglas Engelbart, and Melvyn Berman, in IEEE Transactions on Human Factors in Electronics, March 1967.

Sketchpad: A Man-Machine Graphical Communication System, by Ivan E. Sutherland (Garland Publishing Inc., New York City and London, 1980), reprints his 1963 Ph.D. thesis.