kay a personal computer for children of all ages aug72

7/28/2019 Kay a Personal Computer for Children of All Ages Aug72

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A Personal C o ~ p u t e r fo r Children of All Ages

Alan C. KayXerox Palo Alto Research Center

l\bstractThis note speculates about the emergence ofpersonal, portable information manipulators andtheir effects .when used by both children andadults. Although i t should be read as sciencefic tion, current trends in miniaturization andprice reduction almost guarantee that many of thenotions discussed will actually happen in thenear future.

-TO know th e world one must constructi t . --Pavese

For.lllany years it ha s been a tradition to attemptto cure ou r society 's i l l s through technology:-You have slums? Let 's build low-cost housing!"You can ' t afford that TV? We'll build a cheaperone and you can buy it on time, even though itwill break before you've finished paying for i t !"Your kids aren ' t learning and education i s to oexpensive? We'll build you a teaching machine.for less ~ i c h will guarantee your kids wil l passtes ts!"Unfortunately, most of these "cures" ar e no more 'than paint over rust , th e sources of th e ini t ia l problems s t i l l remain. Educational goals areeven more obscured by the diverse models of th e ;.end product" which exist : th e society wants~ r e members of the society (cultural genetics),the parents may want success, conformity, fame, ,;or don't care, the kid is not asked (he may jus twant to plant beans and watch them come up).What about the teachers? They, of course, rangefrom enlightened human beings (who have a goodmodel of themselves, what i t is that they are trying to communicate, and 'what the child'scurrent model of th e s ituation i s ) , to thosewell-intentioned people who would l ike to teach(but lack ta len t ) , to those who take it as a job,or worse, drifted into it because Ned" was th eeasiest way through college and now begrudgethsir fa te through thei r young charges. ,Technologists point out that at leas t th e bottomcategories would be eliminated through a teachingmachine. What they seldom u n d e r s ~ a n d i s tha t.mat i s delivered is a box which a t bes t squarely"f i t s th e middle category: well intentioned but .lackinq . talent! Can technology ever deliver a . . ,.box with the at tr ibutes of the f i r s t cateqory o f '

teacher? Maybe. But f i r s t , i t must d c c i c ~ tha tit i s a necessary and desirable goal to do so .What ....e would l ike to do in this b:--.il:-i" note i s todiscuss some aspects of the l e a r n i ~ q ~ r o c e s s"'hich we feel Ctl:1 be augmented thrr..\.'qu.technological r:ledia. Most of th e nctl.ons have at their root a nu:nber of theories about th e childthat l ie much closer to Piaget than to Skinner.We fcel that a child i s a "verb" rather than a-noun", an actor rather than an o b j e c ~ , he i s no t'4 scaled-up pigeon or ra t , he is trying to ----acquire a model of his surrounding environment in .order to deal with i t , his theories are-practical" notions of how to get from idea A toidea B rather than "consistent" branches offormal logic, etc . He \-"Quld like to hook intohis current modes of thought in order toinfluence him rather than jus t trying to replacehis model with one of our own.We,do not feel tha t technology is necessaryconstituent fo r this process any m o t ~ than i s th ebook. I t may, however, provide us ""H.h " better-book", one which is active (l ike th e c ~ l i 1 d )rather than passive. I t n:ay be something ....i thth e attention grabbing powers of TV, butcontrollable by th e child rather than th enetworks. : r tcai l ' bel ike ' a piano: (a product oftechnology, yes) , bu t one which can be a tool, atoy , 4 medium of expression, a source of unendingpleasure and delight and, as with most gadgetsin unenlightened hands, a ter r ib le drudge!!This new medium will not "save th e world" fromdisaster. Just as with th e book, it brings a newse t of horizons and a new se t of problems. The,book did, however, allow centuries of h ~ ~ a nknowledge to be encapsulated and transmitted toeverybody, perhaps an active medium can alsoconvey some of th e excitecent of thought andcreation: .


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~ IZap! with a beautiful flash and appropriatenoise, J ~ y ' s spaceship disintegrated, Beth had

~ n Spacewar again. Tho nine-year-olds werelying on the grass of a park near thei r home,their DynaBooks hooked together to allow each ofthem a viewscreen into th e space world whereBeth's ship was now floating triumphantly alone..y' wanna play again?" asked Jimmy."Naw, said Beth, "I t ' s to o easy."Well, in real space you'd be in orbi t around th esun. B e t c ~ o u l d n ' t win then:"Oh yeah?" Beth was piqued into action. "Howcould we do th e sun?"Well, uh , l e t ' s see. When th e ship 's in spacewithout a sun, it jus t keeps going 'cause there 'snothing to stop i t . "1henever we push the thrustbutton, your program adds speed in th e direct ion 'the ship i s pointing." .Yeah. That's why you have to turn the ship andthrust back to get it to s top." , She i l lus t rated . 'by m a n e u v e r i n ~ her ship with a few practiced 'button pushes on her DynaBook. "But th e su nmakes things fa l l into it i t ' s not the same.""But look, Beth," Jimmy aimed her ship, "wbenyouhold th e thrust button down, it s tar ts going '"fas ter and f a s t ~ r , jus t l ike Mr. Jacobsen saidrocks and things do in gravity."o h yeah. I t ' s jus t l ike th e rock had a j e t on;it pointed towards th e earth. Hey, what aboutalso adding speed to the ship that way?"

Bere look." Her fingers started ' to fly on th eDynaBook's keyboard, altering th e prO


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do i t by hand or to pass i t on to someone else.And besides he had jus t thought of a new way tolook at their f igures while ,on the plane.By then, Beth had discovered that her problem wasr idiculously easy i f th e su n was placed atzero", and sh e s i ~ p l y subtracted a l i t t le b itfrom the "horizontal" and "vertical" speeds ofhe r craf t according to where th e ship waslocated. All of th e drawing and animations sh eand the other kids had done previously wereaccomplished by using relative notions whichcoincided with th e scope of the i r abi l i t ies a tth e time. She was now ready to hold severalindependent ideas in he r ~ n d . The in tuit ivefeeling fo r l inear and nonlinear motion that th echildren gained would be an asset fo r l a t e runderstanding of some of th e greatgeneralizations of science.After getting her spaceship to perform, sh e foundJimmy, hooked to his DynaBook, and then soundlytrounced him unt i l 'she became bored. While hewent off to find a less formidable foe, sh eretrieved a poem she had been writing on he rDynaBook and edited a few l ines to ~ p r o v e it

........

I t is now within th e reach of current technologyto give a l l th e Beths and the i r dads a "DynaBook"to use anytime, anywhere as they may wish.Although it ca n be used to communicate withothers through th e "knowledge ut i l i t ies" of th efuture such as a school "library" (o r businessinformation system), we think that a largefraction of i t s us e wil l involve reflexivecommunication of th e owner with himself throughth i s personal medium, much as paper an d notebooksare currently used.A tool i s something that aids manipulation of amedium and man is cliched as th e "tool buildinganimal". The computer is also regarded as a tool

. by many. Clearly, though, th e book is much morethan a tool , and man i s much more than a toolbuilder he i s an inventor of universes. Fromth e moment he learns to se e and to use language,each new universe serves as a medium (andconstraint) of expression in Which imaginedstructures ca n be embedded, usually with the 'aid 'of tools. What'about computers? They are ,clearly more than a tool also, though in typica1 .HcLuhanesque fashion, much of their content ha sbeen adopted from previous media, and thei r ownattr ibutes are j u s t beginning to be discovered.What then is a personal computer? One would hopethat it would be both a medium fo r c o n t a i n i ~ g and,expressing arb i t rary symbolic q o ~ i o n s , . a n d also a .collection of useful tools for manipulating these',structures, with ways to add new tools to th e .

~ e p e r t o i r e . Another rarely invoked constraint i sthat it be super ior to books and printing in a t .:.leas t some ways without being markedly inferior.in others . (The previous remark seems to 'disallow known commercial display devices fromconsideration.) "Personal" also means owned byi t s user (needs to cost no more t hana TV) andportable (which to me means that th e user. ca n...Uy. carry th e device ~ ~ things a t the

One must learn to think well beforelearning to think. Afterward itproves too dif f icu l t . "-A. FranceI t ha s recently become fashionable forresearchers in ar t i f ic ia l in tell igence and (t o acertain extent) in education to examine th e waychildren gain their models of th e world. ( I t wasonce thought that a simulation of in tel l igentbehavior could be obtained throughnonanthropomorphic means.) Following the lead ofNewell and Simon, Papert an d Hinsky, Hoore andAndersen, many are now in terested in what l i t t l ei s knoWn about th e acquisition an d manipulation' of human knowledge by both children an d adults .Of particular in te res t are theories of earlydevelopment and model building e p i t o ~ i z e d byPiaget, Bruner, Hunt, Kagan, among others whostudy what a child does a t various stages ofdevelopment.There i s another closely related group that isinterested in discovering j u s t what children arereally capable of a t various levels of maturity.We must mention Montessori, who was one, of th ef i r s t to decide that children were much more, adept a t learning during early years (2-5) thanwas generally supposed. O. K. Moore ha s shown,via a reactive environment, that even very youngchildren ca n learn to read, ,write and abstract ., Shinichi Suzuki ha s successfully taught thousandsof children between 3 and 6 to play th e violin .Work by BrUner an d Kagan ha s demonstrated tha tchildren, even in the i r f i r s t year (o r f i r s t

~ ~ - - - - - - - - - - . - - - - - - - - - - - - - .. --.......I t i s in teresting how provable a sociological"theory ca n be. There not only i s ample evidenceto support the idea tha t children aretremendously capable, but there also exists anequal body of evidence ( g a t h ~ r e d by morepessimistic souls) to show that children arereally quite s tupid and require e n d ~ e s srepeti t ion in order to learn. The obviousHawthorn ef fec t says that we should be as' ,optimistic as possible and the children wil l save

, WI .very time. '


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=onth), ar e capable of visual discrimination an dgeneralization far beyond what was previouslysupposed. (2)The work and thoughts of o. K. Moore and Seymour, Papert particularly influenced 'the notions whichle d to th e DynaDook. Both men feel that thechild i s an active agent, a creator and explorer,and is far more capable intel lectual ly than isgenerally supposed.A number of th e principles which le d to Boore' s"talking typewriter" are worth examination. Hefeels that i t i s not so much that children lack along attention span, but that they havediff icul ty remaining in th e sarne role withrespect to an idea or act ivi ty. ~ r o l e of"patient l istener" to an idea can quickly lead to

b o r e d o ~ and lack of attention, unless other rolescan also be assumed such as "active agent","judge" or "game player", etc. An environment~ i c h allows many perspectives to be taken isvery much in tune with th e differentiating,abstracting and in tegrative act ivi t ies of th e 'child.A safe and covert" environment, where th e child

'can assume almost any role without social orphysical hurt i s an important par t of th e day.Although it is necessary that sk i l l s andknowledge be occasionally put to serious testbefore peers and adults, there must also be timesof absolute safety for "winging i t " withoutreproach. A "productive" environment, in Moore'sterms, is one in which things that are learnedcan be used as par t of (and fo r further learningof ) new ideas. Final ly, an environment which i simmediately responsive to th e chi ld 's act iv i t iesand allows him to gain !. ~ himself i s ."tremendously important.The -talking typewriter" was a crystall ization ofthese ideas into a device ( in i t ia l ly simulated by'a graduate student behind a wall) which led tomany beautiful insights into th e abi l i t ies an dinclinations of th e young child . (3)

"Should th e computer program the. kid, or should th e kid programth e computer?"-s. PapertPapert 's work in "teaching kids thinking" throughgiving them an environment in which they ca n 'write programs for thei r own ends (animations,games, etc. ) is strik ingly similar in sp i r i t to. Moore's, although th e philosophical background i sthat of AI and Piaget. (4,5,6)The language LOGO i s used (via a timesharingsystem) through terminals which allow tex t . 'graphics, music and a lumbering mechanical"turt le" to be under control of a chi ld 'sprograms. Papert 's LOGO efforts are "CAl" o n ~ yi f th e acronym stands fo r Computer Aided 'Intuition (o r Inspiration) r a t h e r tha'nInstruction. Much of current computer-related .education, however, i s based on ProgrammedLearning wich wa.s largely dadved from ,Behavioralists' experiments with rats andpigeons._ Papu t ' . view,. on the other hanel,. va s

highly i n f l u ~ n c e d by contact with Piaget and hiswork which (oddly enough ) was drawn mostlyfrom studies of actual children and how theythink about th e world.Our project i s very sympathetic to the l a t t e rview. Where some people measure progress inanswers-right/test or tests-passed/year, we aremore in terested in "Sistine-ChapelCeilingS/Lifetime. This i s not to sa y that sk i l lachievement i s de-emphasized. "Sistine-ChapelCeilings are not gotten without healthyapplication of both dreaming and great sk i l l a tpainting those dreams. As b y s t a n d ~ L. d.Vinciremarked, "''lhere th e spi r i t does no t work yi thth e hand, there is no ar t" . Papert has.pointedout that people will willingly and joyfully spend, thousands of hours of highly physical and mentaleffort in order to perfect a sport (such asskiing) that they are involved in . Obviouslyschool and learning have no t been madein teresting to children, nor ha s a way to getimmediate enjoyment from practicing intel lectualski l ls 'generally appeared.With Dewey, Piaget and Papert, we believe that

c h i l d r ~ n "learn by doing" and that much of th ealienation in modern education comes from th egreat philosophical distance between the kinds of' th ings children ca n "doN and much of 20-centuryadult behavior. Unlike th e African child whoseplay with bow and arrow INVOLVES him in futureadult act ivi ty, American child ca n ei therindulge in i r re levan t imitation (the child in anurse's uniform taking care, of a doll) or isforced to part icipate in activit ies which willnot bear f rui t fo r many years and wil l leave himalienated (mathematics: "multiplication i s GOODfor you - see, you can solve problems in booksl"music: "practice your viol in , in three years wemight t e l l you about music," etc . ) .I f we want children to learn any particular area,then it is clearly up to us to provide them wi,thsomething real and enjoyable to "do" on their wayto perfection of both th e art ' and th e sk i l l .Painting can be frustrat ing, yet practice is fu nbecause a f inished picture is a subgoal which ca nbe accomplished without needing to tal mastery ofthe subject.Playing musical instruments and gaining musicalthinking i s unfortunately much further removed.

~ b s t modern keyboard and orchestral instrumentsdo not provide subgoals.which are satisfying tothe child or adult fo r many months, no r do theyreal ly give any insight into what music i s or howto "do" i t .on one's own. I t i s usually much moreanalogous to "dr i l l and sk i l l " in painting a .billboard "by th e n u m b e r s ~ , and no t even gett ingto use your own numbers or paint!The study of arithmetic and mathematics i s , ingeneral , an even worse si tuat ion. ~ ~ a t ca n a'child "do" ,with multiplication? The usual answer :-is work problems in th e math book! A typical .establishment reaction to this is that somethings just have to be learned by dr i l l " .(Fortunately kids don ' t have to learn thei r:nativa tongue under those circumstances.)'Papert . kids need to use lIlultipUcation to make


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the size of thei r computer-drawn animationschange. They have something to "do" with i t .-Genetic Epistemolo9Y-

The l i fe work of Jean Piaget is both wide anddeep enough to defy any cursory summation. Sincethere exist s ~ a r i e s and cri t iques (e.g. FUrth:Piaget and Knowledqe: Theoretical Foundations), amore eclec t ive strategy is in order.Two of Piaget 's fundamental notions areat t ract ive from a computer scien t i s t ' s point ofview.The f i r s t i s that knowledge, part icularly in th eyoung child, is retained as a series o f "operational models, each of which i s somewhat adhoc and need not be lO,gically consistent with the 'others . (They are essential ly algorithms an dstrategies rather than logica l axioms, predicatesand theorems.) I t is much la ter in developmentthat logic i s used and even then throughextralogical st rategies .The second notion i s that development proceeds in ,a sequence of stages (which seem to beindependent of cultural environment), each onebuilding on th e pas t , yet showing dramaticdifferences in abi l i ty to apprehend, generalizeand predict casual relat ions. Although the ag ea t which a stage i s attained may vary from childto child, th e apparent dependency of a stage on,previous stages seem to be invar iant . Anotherpoint which wil l be important l a t e r on i s that 'language,does not seem to be th e mistress ofthbught but. rather th e h a n d ~ a i d e n , in that therei s considerable evidence by Piaget and others ,that much thinking i s nonverbal an d iconic.a. StagesBoth Piaget an d Bruner have coined names for th estages of development. Bruner 's are a b it moredescriptive so they are included here also .

: 'Aqa Piaget Bruner Propertieso Sensorimotor Enactiva Reflexivem:vERSIBILITY'Discrepancy/NoveltyObject Conaervation1"

,4

8

Preoperat iona l

ConcreteOperational

I'onaal.

Iconic:

Speech s tar tsH a s S I NotLength Con-aervedLengthConservationNegation (Inversion)

f(x) y ,f ' y) - xReciprocity

Symbolic Mul.t1 v. ConservationHypotheses/l)eductiona

I f th e stage dependency i s real , it may be worsethan useless to t ry cramming context fromupstream stages down children 's throats unt i lthey are ready. For instance, it i s nowfashionable to teach children (i n "new ~ a t h " )point set topology on a 2 - d i ~ e n s i o n a l cartesian'coordinate system a t th e ear l ies t possible age..The wisdom of this i s contradicated by a seriesof Piaget 's e x p e r ~ e n t s which show that childrenin th e operational stage simply do not grasp t he 'notion of a coordinate system unt i l la ter on .However, they do have very sophisticated notionsof topology, connection, enclosure and grouping -a l l RELATIVE concepts. These facts were used byPapert and Goldstein to teach g e o m ~ t r y andtopology without reference to a global c o ~ r d i n a t osystem - a much more sat isfying state o'f a f f a ~ r s .I f we believe in the veracity of "operational"(semantic) rather than "predicative" ( logical ,syntactic) ~ o d e l s , a quarrel ha s to be cade withthe very syntact ic notions currently in favor in'-New Math". Fo r example, in natura l numbersl

are said to be numerals for the n ~ e r e ight .This concept i s not only misleading andnonsemantic, it i s also wrong. (What number I s-8/3" a "numeral" for?)Minsky has noted: "The trouble with new math i stha t you have to understand it every im e you useit. (20)Piaget ' s an d others ' work on the bases an d formsof children 's thought i s a fai r ly convincingargument for believing that computers are analmost ideal medium fo r the expression of achi ld ' s epistemology. hbat is an "operationalmodel" i f not an a l g o r i t ~ , a procedure fo raccomplishing a goal? Algorithms are fai r lyinformal and not necessarily logically consis tent(a s anyone who ha s ever spent a few hoursdebugging a program well knows). This f i t s inveIl with th e chi ld ' s viewpoint which i s globalan d interested in structure rather than s t r i c timplication of "truths". On th e other hand,computer also a ids in , th e formation of sk i l l sconcerning "thinking"1 st rategies and t ac t i cs ,planning, observation of causal chains, debuggingand refinement, e tc . Rarely does a chi ld have achance to pract ice these sk i l l s in an environmenttha t i s pat ient , c o v e r t ! ! ! ! ~ !


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The DynaBook- I wish to God these calculations wereexecuted by steam!"Charles Babbage (age 19)ca. 1803-The Analytical Engine weavesalgebraic patterns, jus t as th eJacquard Loom weaves patterns in . ille.- -Ada AugustaCountess of Lovelace

We now have some reasons fo r wanting th e DynaBookto exist . Can it be fabricated from currentlyinvented technology in quanti t ies large enough to bring a sell ing (o r renting) price within reachof millions of potential users? The set ofconsiderations which pertain to the morepractical aspects of th e device such as s ize ,cost, capabil i ty , etc. ) are jus t as impOrtant asth e more abstruse philosophy which prompted us in .th e f i r s t place. The next few pages discuss some .:.of the tradeoffs involved, and wil l attempt toconvince the reader that a target price of $500i s no t total ly outrageous. The current costtrends and size of th e various components dooffer considerable hope that th e target ca n bereached. The analogy to color TVs which can be801d for under $500 i s also important to keep inmind. Now, what should th e DynaBook be?The size should be no larger than a notebookJweight less than 4 lbs . , the visual displayshould be able to present a t leas t 4000 printinq ;quality characters with contrast rat iosapproaching that of a bookJ dynamic graphics ofreasonable quality should be possible, . thereshould be removable local f i le storage of a tleast one million characters (about 500 ordinarybook pages) traded off against several hours of audio (voice/music) f i les .

The active in terface should be a language whichuses l inguist ic concepts no t far removed from theowner of th e device. The owner"will be able to ,maintain and edi t his own f i les of tex t andprograms when and where he chooses. He ca n use ...h i. DynaBook as a teminal when a t work (o r aa a.:: ,

connection to th e l ibrary system when in school).When he is done perusing and ha s discoveredinformation that he wishes to abstract and takewith him, it ca n rapidly be transferred to hislocal fiio storage. The umbilical connectionwil l supply not only information bu t also extrapower fo r any motors tho device might have,allowing high bandwidth transmission of aboutJOOK bits/sec to th e f i le storage, or 1 SOO-pagebook in 1/2 minute. The bat ter ies will also beautomatically recharging during this connection-Books can now be instantiated" instead ofbought or checked out . One can imagine vendingmachines Which will allow perusal of information(ranging from encyclopedias to the la tes tadventures of wayward women), bu t will prevent. f i le abstraction unti l th e fee has been paid.The abil i ty to make copies easily and to "own"one 's information will probably not debil i tateexisting markets, jus t as easy xerography hasenhanced publishing (rather than hurting it assome predicted), and as tapes have not damagedth e LP record business but have provided a way toorganize one's own music. Most people are notin terested in acting as a source or bootlegger,rather , they l ike p e ~ u t e and play with whatthey own.

'A combination of this "carry anywhere" device anda global information ut i l i ty such as th e ARPAnetwork or two-way cable TV, will bring thel ibrar ies and schools (not to mention stores andbillboards) of th e world to th e home. One canimagine one of th e f i r s t programs an owner willwri te. is a f i l t e r to eliminate advertising!Input will be via keyboard (most people now learnhow to type) or via .secretary-cum-keyboard in th et radi t ional manner. Or by voice. The f i lesystem of th e device can easily allow audio f i les .(with digital headers), however, they would havet o be transcribed before any editing could bedone. Although "interactive graphics" wil l be

~ i m i t e d because of capacity, sketches ca n beretained and edited as facsimile f i les .Ifhe Display

Either a f la t panel display, such as th e plasmapanel, or a connection to an external CRT i sdictated by th e size requirement. The powerspecs disallow th e plasma panel ( i t can draw 5amps when fully l i t ) , and th e need to use itanywhere eliminates th e almost (but not quite)ubiquitous CRT. tihat then is lef t? We clearlywould l ike a technology that requires power onlyfo r state changing, not fo r viewing - i . e . ca nbe read in ambient l i g h t ~ phase Transit ionLiquid Crystal (16) can be x-y addressed and'wil l. obligingly turn opaque under the influence of a ..low-power elect r ic f ield. Further, the displaywil l maintain i t s e l f with very l i t t l e additionalpower, th e electrode widths can be as small as 1mil, and th e s tate of th e ent ire S12x5l2 panelcan be changed for less than 1/2 watt. (Note:. This is a current technology even though no onehas yet bui l t a S12xS12 panel.).I n order to put up book quali ty characters a t. ,noEmal viewing distance . we need' to have a qood

" " . .


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in tuit ive modol of tho eye and to make us e ofsome recent discoveries at ou r la b in th e a r t ofcharacter generation (15). In order to build anin-house research terminal system with printingquality CRT display, an experimental "loadablefont" character generator was designed andconstructed. Any 128 character font which ca n bedefined in terms of up to J2xJ2 b it matrices canbe dynamically loaded into a fast bipolar m e ~ o r yto allow real-t ime scan conversion of ASCII t ex t .Fri l l s such as size, in tensity , overlaycharacters (underlines, etc.) ar e also p r o v i d e d ~All photos are of the actual screen (at 875 scanrate) an d are unretouched.

The G O ~ ' Y ...._.and The ECSTACY

A i\OVEI. OF ~ I I C I l E I . A i ' : G E L O

by Irving Stone

THE STUDIO

1

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. Fiq. 1 . "Bodoni-Liks" Font .(19)r - -T l Je ACrONV-, . . . and The Ees r ,\CYIl A NOVEL OFl\lICIIEI.,\NCiEI.O.,

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by lrvlnn Stone

THE STlJDIO

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. : . I hisonc = tlJatnnc1 " K k ~ i l l.'t.l.t : = ,\ 'V + .om:f" f ttl i.,i)nc := slrp S1l1I1i/IISiI", pfilll(: thisnnc. : t .l l):

tNiI .

t ~ K ' ; ~ / ~ _ : ~ ~ ~ . ~ ~ U ~ ~ ~ U : o t b ~ _ r : ..#s%s> ]Pig. 4. Spurious Algol in -Times Roman-Like- FontThe f i r s t interest ing discovery was that th e -display looked much bet ter than it "shouldM i .e . , .th e characters seemed much more round than the .quantization level seemed to indicate , yet,. when.they were blown up larger size, they quickly : became ugly. intui t ive reason fo r th is ha sto do with the inherent noise reducing f i l t e rfunction of the optic t r ac t that , essentially, . f i r s t averages th e signal (using an averagingwindow of about .0 20 of ~ r c ) which turns smallcorners into fuzz, then different iates over alarger area to tweak th e scene back into a sharp.image. The effect of this f i l t e r i s to removesmall isolated gl i tches and, lucki ly for us, toallow matrix defined characters to look beautifulwhen th e matrix is small. I t also par t ia l lyexplains why 875 l ine TV seems to be subjectivelymore than twice as good as 525 a t 2 2- v iew in gdistance. The scan l ines and their spaces 'areto o large to be f i l tered for 525 since they areabout l / ~ O higb.. .


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Small characters are tough since the defini t ion=atrlx is l imited, yet more can be done thanmight be apparent. Two t r icks that work are tochange th e aspect rat io of the characters(height: width ~ 2 : 1 , thus making 450 angles into600 ) and to us e multiple width strokes for a bold.face effect even on absolutely t iny characters(this t r icks the eyes' f i l ter into trying toenhance the character rather than to remove it asnoise).To sum up . The display surface should probablybe l iquid crystal having at least SO - 100 raster 'points/inch, an aspect rat io of about 2 pointshorizontally for each point vert ical ly and ato tal ras ter of ~ l 0 2 4 x l 0 2 4 .

ICeyboardof course th e keyboard should be as thin aspossible. I t may havo no moving parts a t a l l butbe sensi t ive to pressure, feeding back a cl ickthrough th e loudspeaker when a successful press .has taken place. Keyboards of this kind havebeen available for several years.Once one ha s gotten used to the idea of no moving'parts , he is ready for th e idea of no keyboard 'a tal l :Suppose the display panel covers th e ful l extentof th e notebook surface. Any keyboardarrangement one might wish can then be displayedanyWhere on the surface. Four strain gaugeslDOunted under th e corners of the panel wil lregis ter th e position of any touch to within .3/16- Which is close enough. The bottom portionof the display panel ca n be textur'ed in va%'iousways to p e ~ t touch typing. This arrangeRentallows th e font in w h i ~ h one i s typing to beshown on th e keys, special characters can be ",windowed, and user ident i f iers can be selectedwith one touch.

Pile Storage 'The only technology that currently exis ts whichca n handle th e modest, though important, demandfor a writable f i le storage is magnetic oxideplast ic in th e form of tape casset te or floppydisk. Until recently, tape handling typical lyrequired a conglomeration of pinch rol lers ,capstans, solenoids and motors. Now the problemsof constant tape tension and differential drivehave been solved by a nw:lber of canpanies, th e. most elegant being the cassette by 3M which uses -magic- driveband which contacts th e outside ofthe tape takeup reels and requires only on e motorfo r read, write, search and rewind. Four tracksof tape a t a b i t density of 1600 bpi allows 6400bits/ inch to be stored and retr ieved. Ourrequirement fo r 8M bits thus demands 1250 inches(o r 105 feet) of tape in the casset te. Of coursethere wil l be gaps, e tc . , so to play safe , ourfantasy casset te wi l l have 50' more tape or 150feet . 'the f i le directory wil l be placed in the middleof th e tape (a s in .the LINe) so tha t only 1/4 thetape t raversal tima on th e average' i s required to

. acee.. it . From there , the.verage cUatance. of.

any f i le i s also jus t 1/ 4 th e length of tapeproducing a tota l average random access time of1/2 tape t raversal time. The search speeddepends almost ent i rely on th e desired battery. drain rate and th e capacity of th e motor.Cassettes of th e 3r1 type ca n be positioned a t 180in/sec, lao feet of tape ca n be traversed inabout 7 seconds so the average latency to a f i leis about 4 seconds. This i s very respectable.However, these speeds require far too many wattswhen using th e bat ter ies alone. A morereasonable rate for search on ba t te r i es would be60 in/sec giving a latency of about 10 secondsfor access to a f i le .The floppy disk requires two motors (one a-stepping motor for positioning the head)' and isusually ru n continuously. The la t ter would notbe possible for battery operation, and the devicewould have to be star ted and stopped. The onegreat advantage of th e floppy disk i s thatswapping can be done on one track while s t ~ l l 'allowing decent access time to f i les . (Thenotion and ut i l i ty of swapping storage wil l bediscussed in the section on th e processor.)

Processor and StorageThese two categories represent, respectively, thel eas t expensive and th e most expensive c o ~ p o n e n t ain our fantasy machine. They are presentedtogether because of the grea t influence th eprocessor ha s ()n th e amount of primary memoryneeded.What follows i s an attempt to show that both th eperformance and th e packaging requirements ar enot necessarily incompatible with today'stechnologies (although a hand wil l occasionallyhave to be waved). Just as in th e HP-35 pocketelectronic "sl ide rule", th e main savior of ou rdreams i s cheap LSI components. The HP-35 usesfive LSI chips with an equivalent of 30,000. t ransistors, for an average density of 6000t ransis tors /chip. Even better packagingdensit ies are now being accomplished. The priceot a packaged LSI chip seems to approach $12.00asymtotically over a two-year period, then may

' dip s u ~ e n l y to about $5.00.Complete CPUs are'now available on single chips.The challenge now l i e s more in determining whatCharacteristics th e processor should have ratherthan using jus t anything that wil l packagenicely. '

'LSI Random Access Memory is now routinely, available in 1024 l ,b i t chips (700 ns cycle time).fo r l/bi t packaged. A 4096*1 chip ha s now been:announced an d looks as though it ca n be packagedfor .35/bit . An SK*16 memory would thus costabout $460 ( s t i l l to o much, but encouraging).The rechargeable-battery state-of-the-art ha sbeen considerably advanced by th e advent ofportable shavers, tape recorders, toothbrUShes,TV, etc . We may expect even higherperformance/charge in th e futU%'e.. .Since les i. th e current estimate of the. number of chips, needed in ' the DynaBook, we ca n be


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reasonably sure that th e electronics part of th e ,device wil l package quite nicely.The processor is envisioned as being implementedas 1, or a t most 2, LSI chips. Such devicesalready exi s t fo r less than $100 with a projectedprice of less than $15. They typical ly containth e equivalent of several thousand t ransistors"have registers fo r a p r o g r ~ ~ counter, arithmeticoperations, an instruction return stack, etc . ,and even may us e a carry-lookahead arithmeticuni t . A standalone "smart teroinal" that usesone of these chips for a processor (and includesmemory, a keyboard, a display and two cassettes)is now on th e market for about $6000 (Datapoint2200).Since the DynaBook i s an attempt to be much morethan a terminal, for much less cost , a grea t dealof careful thought needs to be expended on the .. processor-memory design. We would obviously l iketo maximize th e us e of th e expensive corereplacement RAMr th is can be done by:1. Efficiently encoding th e operators fo r maximum 'instruction densi ty/bi t .2. Encoding the basic logical data element (theordered set) to minimize space r e q u i r ~ e n t s .3. Removing an y systems routines from th e RAM(including th e interpreter) so that a l l of thespace ca n be ut i l ized by th e user.4 . Mapping th e virtual address space onto th ef i le device, so that the RAM serves as a cachefor most recently used portions of memory.(oOubting Thomases, who feel this would beworthless on a tape machine, are advised to 'consult the LINe l i terature (17,18) for a ' , 'description of a similar scheme which ha s

been successfully used fo r years by thousandsof users.)5 . Eliminating th e need for a re'sidEmt: "system" per :se by merging th e concept of f i les with uservariables, by permitting the user to conversedirect ly with the interpreter , and by using: 'the multiple control path evaluator to .allow "interrupts , etc . , to be handled within the 'ayatem. (7,8) ---

-The thought of th e Middle Agesvas not l imited, but perhaps i t svocabulary was.", '-williamsIn ,mat fashion should anyone of a potent ial lyvide variety of users communicate with himself ."through his machine? A language containingfeatures tha t supply -a l l things to a l l people" .ia clearly not possible. Neither i s anWextensible language- in the usual sense. withthese two tempting sinkholes removed fromconsideration (by defini t ion, as it were), whatremains i s a chance to present to a user a verysimpleminded language (which r e ~ e a l s the trues t a t . of programming semantics) that ,'nonetheless, i s capable of a wide 'variety of '

I expression. W ~ l l " jus t what i s it that C o m p u t e ~have over other lIlessaga systems? For. em. thiz:aq, ,

they ca n delay a message indefini tely (memory),they ca n transduce th e message into othermessages (processing), and they ca n representt r a n ~ d u c t i o n s themselves as messages(procedures) The us e of th is language i s essent ial ly divided, into two activit iess 1 . giving names to objectsand classes (memory association), and 2.retr ieving objects and classes by supplying th ename under which they had been previously stored.A process consists of these (act ivi t ies) an d i sterminated ~ e n there are no longer any names .under scrutiny. Although a l l of s u c ~ a languagecan be easi ly derived from jus t these two,notions, a few names would have an a p r i o r i ~meaning in order to allow interest ing things tobe done r ight away.The following principles should be used, in th edesign of th e DynaBook language1. We need a uniform notion as to what objectsare, how they may be referred to , and howthey can manipulate other objects .2. I f each object ca n have i t s own control path,then there must be a concise way to coordinate and "control- these paths when morethan one i s active.

. 3. The evaluation of a control path should followsimple rules which show how objects are passedmessages an d return results .4. Every object in a system should be redefinable

in terms of other objects .The basic idea i s to exploit th e duali ty between'functions and tables (o r processes and memory).English has nouns which refer to -objects" , and.verbs which refer to "actors- and "relators".This i s a Newtonian epistemology. Hodern physics.and philosophy tend towards the idea that both"objects" and "actors" are jus t different aspectsof th e notion of process. A process has s tate (aBe t of relat ions having only to do with i t ) which.'.changes as time (defined as interact ions withother objects) passes. Using this view "data" isa process which changes "slowly, "function" i s a 'process vhich changes more rapidly. Each processhas the logical a t t r ibu tes of a complete -microcomputer: they ca n have inputs, give backoutputs, act as a memory on fi le system, performcomputations, be interrupted, etc . since acomputer" can simulate a l l other computers(modulo time and space), having th e notion of a 'process in a l a n ~ u a g e allows useful ideas such as: 'arrays, records, recursive procedures, etc . , tobe added to th e repertoire a t any time. .'The techniques for evaluating such a languagedirect ly by hardware are well known and arewithin reach of a single chip p r o c e ~ s o r . (7)'The notion of multiple control paths allows th eseparate notions of "f i les" , operating system","monitor", e tc . , to be replaced by the 's ingleidea that th e user i s also a process (and thus'has a ta te which consists of variables an d .bindinqs, e tc . ) . 'When he leavea th e m a ~ e , h i.


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process is passivated unt i l th e next time herejoins his DynaBook. His state (which i s nowactivated) constituted "f i les" while he was away. 'The control of the evaluation of various programsis also ,accomplished without any additional~ c h a n i s m through direct execution of user input(the "direct" ~ o d e of JOSS, LISP, etc .) . Sincemultiple control paths are allowed, manyprocesses can be in various stages of evaluationand debugging. (1,B,9,10,11,12,13,14)

Sizes and CostsPrevious experience with evaluators of th e kindwe have been discussing indicates that on th eorder of aooo bi ts of control memory is needed toreal ize it in hardware. This memory at presentwould require 1 ROM LSI chip and th e processoranother. I t is not to o far out to assume thatboth ca n be combined in one package withoutstraining the current state-of-the-art . ;Theprice of LSI packages tends to approach S12-14/package because ~ o s t of th e cost to th emanufacturer comes from tes t ing, substrat ing,padding, etc . , a l l rather independent of devicecomplexity (providing yield i s reasonable).Intel l igent encoding of data and code- allowsa bet ter than 3-fold reduction in memory needed,to hold equivalent structures in a somewhatsimilar language such as BBN-LISP. That meansthat aK 16 h i t words of RJ\H are approximatelyequivalent to 12K 36-bit words for BaN-LISP onth e PDP-10.The DynaBook computer can now be postulated as a.Ing1e bu s machine consisting of

1 processor chip, '16 (BKl) RAM memory chips4 %0 controllers (also processor chips - ,why not?)n chips @$14, "'$294.00 for electronics. 'This price has very l i t t l e credibi l i ty because o fscience f ict ion a:rur haiidWiving. However, somebrave readers might decide that it i s ' ,ridiculously high rather than jus t ridiculous!Conclusion

Speculation and fantasy were promised and mostreaders will probably agree by now that thepreceding pages delivered jus t that (along withsome gas an d maybe even a s l ight t inge of 'credibi l i ty? ) " 'We do feel that th e pedagogical merits ofteaching algorithmic thinking, having easyedit ing, etc . (a l l wrapped up in an environmentwhich can go anywhere and can, belong toeverybody), are undeniable. Considerations ofpackaging, power and weight requireznents were,derived from current technology as were theelectronics and are probably t rue. The software' 'knowledge, language design philosophy, and userinterface ideas are a t l eas t 5 Years 'old. The, three main handwaves are the f la t screen low~ display (which does not currently eXISt but". . . . poaaible) , t h e cjuess about how much ca n be '

done "standalone on an SK machine ( i t has notY,et been simulated), and th e price.Suppose th e OynaBook could be sold for $500(ridiculously low compared to current mini 's ,ridiculously hich compared to current TVtechnology), Whe.re is the money to allow mostchildren (and adults) to have one? The averageyearly amount expended/child for a ll his 'education i s only Sa50. One reason tha t somecare was taken with very high quali ty charactergeneration i s that about $90-95/year of thestudent money goes for the purchase, maintenance,etc . of school bOOKS. I f th e D y n a B ~ k couldassume this function over i t s useful l i f ~ ra tl eas t 40 months) then about $300 is madeavailable. Perhaps the device i t se l f should beqiven away as with a looseleaf notebook, and onlythe content (casset tes, f i les , etc .) be sold.This would be similar in sp i r i t to th e waypackaged TV or music i s now dist r ibuted.We have purposely made no quarrel with thosepeople Who feel l i fe can best be served throughsharing resources. The analogy with th e bOOKs t i l l holds: ' l ibraries are very useful , yet oneneither wants to put up with thei r schedules norlocations (o r content) 100\ of the time. What'about terminals say, through radio, as LarryRoberts has suggested? (21) Well, OK, fo rinverting large matrices, but not for graphicsantmation or any other high bandwidth output.Enough Said.Let ' . jus t do i t !

AcknowledgementI would l ike to thank Danny Bobrow very much fo rhelping me to organize th is very "breadthfirst"paper, and Xerox for providing a nice place tothink about ' things l ike th is .

References1. ' :Bush, V., "As We May Think", AtlanticMonthly, September 19462. Pines, M., Revolution in Learning,. Harper Row, Uew York3. Moore, O. K., Andersen, A. R., Some Principles for the Design of Clarifying Educat ional Environments," Chapter 10 inHandbook of Socialization Theory and Research,Goslin (Ed), Rand ~ ~ l a l l y Co. (1969)4. Papert, S ., Solomon, ,C., "Twenty Things To 'Do with a Computer, AI Laboratory, MIT .(1911) ,5 . ' Papert, S ., "LOGO Book Notes, AI Laboratory,HIT (1910)6. Feurzeig, W.; e t a l , "The LOCO Project , Volumes 1-4 , Bolt , Beranek and Newman, Inc.(1911)1 . XAy, A. C -The Reactive Enqine,- U. of

" Utah. Dept. Ccmputer ~ c i e n c e Technical,Report (1969)


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8. A. C., "Plex, A Flexible Extendible ~ -.guage," U. of Utah, Dept. of ComputerScience Technical Report (1968)9. Reynolds, J . , "Gedanken, A Simple TypelessLanguage Which Permits Functional Data'Structures and CoRoutines," ArgonneNational Laboratory Report ANL-762l,September 196910. Fisher, D. A., "Control Structures for Programming Languages, Computer Science Dept.,Carnegie-Mellon University Thesis (1970)11 . Dahl, o. J. , nygaard, K ., "Simula - A Lan-guage for Programming and Description ofDiscrete Event Systems, CACM, October196612 . Teitelman, w., e t a l, "BBN LISP ReferenceManual," Bolt, Beranek and Newman (1911)13. Stachey, C., Towards a Formal Semantics,Formal Language Description Languages forComputer Programming, North Holland PublishingCo., Amsterdam, 196614. Landin, P. J . , "A Correspondence BetweenALGOL.60 and Churches Lambda Notation,W

CACH 8, 89-101, 158-16515 . EngliSh, W., Lampson, B., Bates, R.,Laws, B., Kay, A. C., A High Quality Loadable Font Video character Generator,"

PARe ;echnical Report (1972)16 . wysocki, J . J . , e t a l , CholestericNematic Phase Transit ion Displays," 1971SID Syntposium Proceddings, Winner Publish-.ing, New York17 . Clark, W., "Programming th e LInC," ComputerSystems Lab, Washington University"St.

Loui.s, .Technical Report (1966)18 . Wilkes, M., "Conversational Access to a2048 Word Machine, Computer Systems Lab,

WAshington university, s t . Louis, Technical~ p o r t (1967)

19 . Stone, Irving, The Agony and th e Ectasy,Doubleday20 . Hinsky, M., "Remarks, Prec. Park City Conference on Computers in UndergraduateEducation, u. of Utah, Department of ComputerScience (1968), W. Viavant tEd.) .

ROberts, L., "Extension of Packet Communication Technology to a Hand-Held Personal. Terminal," Proc. SJCC (1912), AFIPS Press ','

kay a personal computer for children of all ages aug72

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