Europaisches Patentamt
`
`European Patent Office
`
`Office european des brevets
`
`111111111111111111111111111111111111111111111111111111111111111111111111111
`@ Publication number : 0 598 54 7 A2
`
`@
`
`EUROPEAN PATENT APPLICATION
`
`@ Application number : 93308968.2
`@ Date of filing: 10.11.93
`
`@) Int. Cl.5
`
`: G06F 1/16
`
`@ Priority: 13.11.92 US 975834
`@ Date of publication of application:
`25.05.94 Bulletin 94/21
`@ Designated Contracting States:
`DE FR GB
`@ Applicant: International Business Machines
`Corporation
`Old Orchard Road
`Armonk, N.Y. 10504 (US)
`
`@ Inventor : Lucente, Samuel Anthony Michael
`83 Kenilworth Drive West
`Stamford, Connecticut 06902 (US)
`Inventor : Balasubramanian, Peruvemba
`20 Hilltop Drive
`Chappaqua, New York 10514 (US)
`Inventor : Sapper, Richard Frank
`Via Beretta 3
`1-20121 Milan (IT)
`Inventor : Lee, Nathan Junsup
`19 Scher Drive
`New City, New York 10956 (US)
`@ Representative : Burt, Roger James, Dr.
`IBM United Kingdom Limited
`Intellectual Property Department
`Hursley Park
`Winchester Hampshire S021 2JN (GB)
`
`@) Pen-based computer system.
`@) A pen-based computer includes a housing
`and a flat panel display integral therewith. The
`computer housing has a rhombohedron con(cid:173)
`figuration with polyhedron-shaped top and bot(cid:173)
`tom surfaces and polyhedron-shaped side and
`end surfaces interconnecting the top and bot(cid:173)
`tom surfaces. The side and end surfaces of the
`housing
`include one adjacent side and end
`surface having an upward exposure, and
`another adjacent side and end surface having a
`downward exposure, with each of the side and
`end surfaces extending at an angle of between
`about 1 0 and 45 degrees from the top surface to
`the bottom surface. The flat panel display for
`the computer is mounted on the top surface of
`the housing proximate one corner, and
`the
`bottom surface of the housing is designed to be
`supported on a horizontal support surface. The
`computer housing has a configuration which
`enables a right-handed user to orient the hous(cid:173)
`ing
`in at least one orientation such that the
`upwardly facing side and end surfaces are
`located along the right side and upper or lower
`ends of the housing to enable the right-handed
`user to comfortably use the computer, and to
`enable a left-handed user to orient the housing
`in at least one other orientation such that the
`upwardly facing side and end surfaces are
`located along the left side and upper or lower
`ends of the housing to enable a left-handed
`user to easily grasp and utilize the computer. A
`switch enables the user to correctly align text,
`data and graphic information on the flat panel
`display with
`the particular orientation of the
`computer.
`
`58 L
`
`28
`Fig.1
`
`34
`
`SA~
`58
`_j
`
`Jouve, 18, rue Saint-Denis, 75001 PARIS
`
`HTC Exhibit 1005
`
`

`

`EP 0 598 547 A2
`
`2
`
`The present invention relates generally to com(cid:173)
`puters and computer displays, and more particularly
`to a pen-based computer with an integral flat panel
`display and digitized screen.
`Recent developments in computer technology
`have been directed toward increasing the speed and
`power of computers while maintaining their compact(cid:173)
`ness. Commonly available computers for a multitude
`of application software programs, such as wordpro(cid:173)
`cessing and spreadsheet tasks, have a full-size key(cid:173)
`board; a relatively large housing enclosing a CPU and
`one or more disk drives; and a CRT monitor which can
`be located and supported on top of the housing. The
`keyboard allows information to be inputted into the
`CPU for processing and display on the monitor. Typ(cid:173)
`ical examples of such computers are the IBM PS/2
`(IBM and PS/2 are trade marks of IBM Corporation)
`series of non-portable desktop personal computers.
`Although these non-portable desktop personal
`computers have been developed with the speed and
`power to handle a multitude of application software
`programs, the size and weight of these computers
`typically relegates them to a desk top or computer
`stand.
`However, "portable" and/or "lap-top" computers
`have emerged as fulfilling the above-mentioned cri(cid:173)
`teria for speed as well as convenience and transport(cid:173)
`ability. These types of computers have a keyboard
`connected (sometimes integrally) to a relatively small
`housing enclosing a CPU and one or more disk drives.
`A lightweight, relatively thin flat panel display is typi(cid:173)
`cally attached to the housing and can be tilted up(cid:173)
`wardly, downwardly and/or removed for viewing.
`Again, the keyboard is utilized to input information
`into the CPU for processing and to output information
`on the flat panel display. The keyboard, CPU and flat
`panel display are relatively compact units which can
`be as small as a briefcase for easy transportability.
`Sti II other developments in computer technology
`have lead to "notebook" computers, which as the
`name suggests, approximate the size of a notebook
`or tablet. These types of computers maintain the
`speed and power of the non-portable, portable and
`lap-top computers in a still smaller and compact de(cid:173)
`sign. The notebook computer typically has a CPU and
`a flat panel display mounted within a housing. A key(cid:173)
`board is connected to the computer for entering infor(cid:173)
`mation into the CPU for processing and display on the
`flat panel display. Commercially available notebook
`computers of this type are marketed by the IBM Cor(cid:173)
`poration under the marks/designations ThinkPad
`700™ and ThinkPad 700C™.
`Further, a more recent development in computer
`technology has lead to "pen"-based computers (also
`referred to as "hand-held", "tablet", "clipboard", "pen(cid:173)
`top" or "hybrid" computers), which are as small (or
`smaller) and as versatile as the notebook computer,
`but use a digitized screen for input of information,
`
`rather than a keyboard. The digitized screen can
`comprise an electromagnetic digitizer, a touch screen
`(resistive) overlay, or other proximity-sensitive
`screen devices which provide a digital output corre-
`sponding to the location of a stylus or finger on the
`screen. The touch screen overlay senses the pres(cid:173)
`sure of a stylus or finger on the screen; while the elec(cid:173)
`tromagnetic digitizer either comprises a screen grid
`which senses a magnetic signal emanating from a
`specially designed stylus, or alternatively, comprises
`a stylus having a coil which senses a position signal
`emanating from the screen. The digitized screen can
`be coupled with handwriting recognition software to
`input information directly into the CPU. Acommercial-
`ly available pen-based computer is marketed by the
`IBM Corporation under the mark/designation Think(cid:173)
`Pad 700T™.
`Although the pen-based computer offers in(cid:173)
`creased flexibility over notebook, non-portable, port-
`able and lap-top computers in being able to easily
`transport the computer while still maintaining suffi(cid:173)
`cient speed and power for a wide variety of applica(cid:173)
`tion software programs, the pen-based computer can
`still be somewhat awkward to use. In particular, pen-
`based computers typically have a rectangular box-li(cid:173)
`ke shape having squared corners, with the flat panel
`display mounted integrally in the upper surface of the
`computer but still supported some distance away
`from the support surface (e.g., from the table top). In
`using the pen-based computer with a digitized
`screen, the palm of the hand typically rests on the
`side of the computer housing when the information is
`inputted using a stylus. The user attempts to enter
`the information using normal writing techniques and
`hand positioning. However, with the box-like shape
`and squared corners, the user can feel awkward sup(cid:173)
`porting the hand in this way over periods oftime, and
`can have difficulty gripping and holding the pen-ba(cid:173)
`sed computer and picking up the pen-based comput-
`er from a support surface.
`Further, the pen-based computers can be partic(cid:173)
`ularly uncomfortable for left-handed writers. This is
`typically due to the ergonomic configuration of the
`pen-based computer, which is designed primarily for
`use by right-handed persons. Left-handed writers
`tend to "curl" the hand around the top of a writing pad.
`However, the sharply angled design of the typical
`box-like pen-based computer also makes this writing
`style awkward and uncomfortable.
`Finally, the known pen-based computers are
`generally designed to rest flat on a support surface or
`to be held on a lap during use. These pen-based com(cid:173)
`puters do not have integral legs or other supporting
`devices which enable the computer to be angled on
`a support surface for proper viewing while still main(cid:173)
`taining a comfortable writing surface in both portrait
`or landscape orientations.
`In any case, there is a demand in the industry for
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`2
`
`HTC Exhibit 1005
`
`

`

`3
`
`EP 0 598 547 A2
`
`4
`
`a pen-based computer which is comfortable to use
`and which can easily accommodate both right(cid:173)
`handed and left-handed writers.
`In accordance with a first aspect of the invention
`there is provided a computer system comprising: a
`housing having a first major surface, facing in a first
`direction, on or in which is mounted a flat panel dis-
`play and a second major surface, facing in a second
`direction, opposite the first surface, for supporting
`the computer system on a support surface, the hous-
`ing having a rhombohedron configuration in which
`the first and second major surfaces are polyhedron(cid:173)
`shaped, the housing further including polyhedron(cid:173)
`shaped side and end surfaces interconnecting the
`first and second surfaces, the side and end surfaces
`including one adjacent side and end surface facing in
`a direction having a component in the first direction,
`and another adjacent side and end surface facing in
`a direction having a component in the second direc-
`tion, each of the side and end surfaces extending at
`an angle of between about 10 and 45 degrees be(cid:173)
`tween the first surface and the second surface.
`A computer system having such a housing config(cid:173)
`uration enables both left-handed and right-handed
`writers to input information comfortably and efficient-
`ly. The computer housing configuration has an ergo(cid:173)
`nomic design which can be used by left-handed writ-
`ers when the housing is in one orientation, and by
`right-handed writers when the housing is in another
`orientation. The configuration of the housing further
`enables both left-handed and right-handed writers to
`use the computer when the flat panel display is in
`either a portrait orientation (vertically aligned) or
`landscape orientation (horizontally aligned). In any of
`these orientations, a switch device in a preferred sys-
`tern changes the display on the flat panel display
`such that the display maintains the correct alignment
`for proper viewing.
`In use, the first and second major surfaces cor-
`respond to upper and lower surfaces which in one
`preferred arrangement are rectangular in shape. In a
`preferred arrangement, the digitized flat panel dis-
`play is mounted on the housing proximate one corner
`of the upper rectangular surface. The side and end
`surfaces of the housing extend at an angle of be-
`tween about 10 and 45 degrees from the upper sur-
`face to the lower surface, and preferably at an angle
`of about 22 degrees, to enable the computer to be
`comfortably used. One side and end surface is visible
`from the top oft he computer, while the other side and
`end surface is visible only from the bottom of the
`computer.
`For right-handed writers, the housing is oriented
`such that the upwardly visible side and end surfaces
`are located on the right side and lower end of the
`housing to enable the user to rest the palm oft he right
`hand on these surfaces for use in the portrait mode
`(flat panel display vertically aligned). The housing
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`3
`
`can then be rotated 90 degrees counterclockwise into
`another orientation wherein the upwardly visible side
`and end surfaces are located on the top end and right
`side of the housing to enable the right-handed writer
`to rest the palm of the right hand on these surfaces
`for use in the landscape mode (flat panel display hor(cid:173)
`izontally aligned).
`Alternatively, for left-handed writers, the housing
`is rotated a further 90 degrees counterclockwise such
`that the upwardly visible side and end surfaces are lo(cid:173)
`cated on the left side and top end of the housing to
`enable a left-handed writer to rest the palm of the left
`hand on these surfaces for use in the portrait mode
`(flat panel display vertically aligned). Finally, the
`housing can be rotated a still further 90 degrees
`counterclockwise into another orientation wherein
`the upwardly visible side and end surfaces are locat(cid:173)
`ed on the left side and lower end of the housing to en(cid:173)
`able the left-handed writer to rest the palm of the
`hand on these surfaces for use in the landscape
`mode (flat panel display horizontally aligned). In any
`of the orientations described above, the user can rest
`the palm of the writing hand on the respective side or
`end surface for comfort and ease of writing.
`The flat panel display for the pen-based comput(cid:173)
`er has a digitized (preferably electromagnetic) screen
`for input of information to the CPU. In a preferred sys(cid:173)
`tem, a switch is located in the housing preferably at
`the opposite edge of the upper surface from the flat
`panel display to change the display on the flat panel
`display for proper viewing in any of the above(cid:173)
`described orientations. The switch provides for auto(cid:173)
`matic or manually selectable reformatting of the ad(cid:173)
`dresses of the-data locations on the screen such that
`the display data is aligned on the flat panel display
`correctly in any of the orientations described above.
`In one embodiment, the pen-based computer in(cid:173)
`cludes display legs stored in recesses in the back sur(cid:173)
`face oft he computer housing. The display legs can be
`pivoted outwardly away from the housing for angled
`viewing and writing on a horizontal surface in either
`the portrait or landscape orientation. The rhombohe(cid:173)
`dron-shaped housing, and in particular the angle of
`the side and end surfaces which taper down to a thin
`peripheral edge (preferably 5mm), facilitates support(cid:173)
`ing the angled computer on a horizontal support sur(cid:173)
`face (e.g., a table top) in a comfortable writing posi(cid:173)
`t ion and at a proper viewing angle. Alternatively, the
`display legs can be stored in their recesses and the
`computer can be hung on a wall or supported on a lap.
`Finally, the pen-based computer can be linked to per(cid:173)
`ipheral equipment (keyboards, printers, hard disk
`drives, etc.) for further application software program
`capabilities.
`In summary, a pen-based computer is provided
`which can be easily and comfortably used by both
`left-handed and right-handed writers. The pen-based
`computer has a configuration which provides a com-
`
`HTC Exhibit 1005
`
`

`

`5
`
`EP 0 598 547 A2
`
`6
`
`fortable writing surface and proper viewing angle
`when the computer is supported either on a flat sur(cid:173)
`face or at an angle. The configuration of the pen-ba(cid:173)
`sed computer further enables the computer to be
`comfortably gripped, held, and easily picked-up from
`a support surface.
`In a second aspect of the invention there is pro(cid:173)
`vided a flat panel display for a computer, comprising:
`a screen display for display of text, data and graphic
`information, a signal path for connecting said screen
`display to said computer for communication of the
`text, data and graphic information, said text, data and
`graphic information being at least temporarily stored
`in said computer and reproducible on said screen dis-
`play in at least one orientation relative to the orienta-
`tion of said flat panel display, a switch for changing
`the orientation of said text, data and graphic informa-
`tion relative to said computer such that said text, data
`and graphic information is properly aligned on said
`screen display relative to the orientation of said flat
`panel display.
`Such a display may be used in different orienta(cid:173)
`tions, ie the display can be rotated in 90 degree incre(cid:173)
`ments while maintaining correct alignment oft he text,
`data and graphics on the flat panel display.
`A preferred embodiment of the present invention
`will now be described, by way of example only, with
`reference to the accompanying drawings in which:
`Figure 1 is a top plan view of the pen-based com-
`puter constructed according to the principles of
`the present invention wherein the computer is in
`a right-handed portrait orientation;
`Figure 2 is a top plan view of the pen-based com(cid:173)
`puter of Figure 1, wherein the computer is rotated
`90 degrees into a right-handed landscape orien-
`tat ion;
`Figure 3 is a top plan view of the pen-based com(cid:173)
`puter of Figure 2, wherein the computer is rotated
`an additional 90 degrees into a left-handed por-
`trait orientation;
`Figure 4 is a top plan view of the pen-based com-
`puter of Figure 3, wherein the computer is rotated
`an additional 90 degrees into a left-handed land(cid:173)
`scape orientation;
`Figure 5A is a right side view of the pen-based
`computer of Figure 1;
`Figure 58 is a lower edge view of the pen-based
`computer of Figure 1;
`Figure 6 is a bottom plan view of the pen-based
`computer;
`Figure 7 is a schematic illustration of the electri-
`cal components of the pen-based computer;
`Figure 8 is an enlarged schematic illustration of
`the mechanical switch fort he pen-based comput-
`er;
`Figure 9 is a schematic of the electronics of the
`rotating function of the present invention;
`Figure 10 is a flow chart illustrating the rotating
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`4
`
`scheme;
`is an equation table illustrating the
`Figure 11
`equations used for the rotating function;
`Figure 12 is a sectional side view of the storage
`and retrieval system for the present invention,
`the keyboard being shown in a stored and locked
`position; and
`Figure 13 is a sectional view of the storage and
`retrieval system of Figure 12 in which the key(cid:173)
`board is shown in a partially removed and un(cid:173)
`locked position.
`Referring to the drawings, and initially to Figures
`1-7, a pen-based computer is illustrated having a
`housing 10 with a display flat panel display 12. The
`housing 10 encloses electronics and/or software (de(cid:173)
`scribed in more detail hereinafter) which enable the
`computer to provide application software programs
`such as word processing and spreadsheet tasks, and
`to display text, data and graphic information on the
`flat panel display 12.
`The housing for the pen-based computer in(cid:173)
`cludes an top housing portion 14 and a bottom hous(cid:173)
`ing portion 16 connected together along the edge 17
`of the housing. The top housing portion 14 is prefer(cid:173)
`ably formed from carbon fiber reinforced plastic for
`durability; while the bottom housing portion 16 is pre(cid:173)
`ferably formed from magnesium for thermal heat dis(cid:173)
`sipation.
`The top and bottom housing portions of the pen(cid:173)
`based computer together form a rhombohedron (a
`parallelepiped whose 6 faces are rhombuses). In par(cid:173)
`ticular, the rhombohedron-shaped housing includes
`a substantially planar top surface 20, and a parallel
`substantially planar bottom surface 22. The top sur(cid:173)
`face 20 and the bottom surface 22 each have a rec(cid:173)
`tangular configuration in plan view and are slightly
`offset from one another.
`The side and end surfaces of the rhombohedron(cid:173)
`shaped housing extend at an angle from the top sur(cid:173)
`face 20 to the bottom surface 22. In particular, refer(cid:173)
`ring to Figure 1, both the right side 26 and the lower
`end 28 extend at an angle of between about 10 and
`45 degrees from the top surface to the bottom sur(cid:173)
`face of the housing, and preferably at an angle of
`about 22 degrees. The right side and lower end have
`surfaces which face upwardly and are exposed in the
`top plan view of Figure 1.
`Forming the other side and end surfaces of the
`rhombohedron are a left side 30 and the upper end
`32. Both of the left side and upper end also extend
`from the top surface to the bottom surface at an angle
`of between about 10 and 45 degrees, and preferably
`at an angle of about 22 degrees. However, the left
`side and upper end are not visible from the top plan
`view of Figure 1, but rather are exposed in the bottom
`plan view shown in Figure 6. Finally, each side and
`end surface tapers down to the distal edge 17 which
`is about 5 mm thick and extends around the entire
`
`HTC Exhibit 1005
`
`

`

`7
`
`EP 0 598 547 A2
`
`8
`
`periphery of the housing. With any of the side and end
`surfaces described above, these surfaces can be tex(cid:173)
`tured to facilitate grasping.
`The flat panel display 12 for the computer hous-
`ing is mounted proximate one corner 34 of the top
`surface 20 of the housing. This corner is adjacent the
`right side 26 and the lower end 28 of the housing. As
`will be described herein in more detail, the location of
`the flat panel display proximate this corner provides
`a design which is comfortable to use for writing over
`periods of time.
`The flat panel display 12 for the pen-based com(cid:173)
`puter comprises a digitized Thin Film Transistor(TFT)
`35 with a backlit screen 36 (shown in Figure 7) which
`displays text, data and graphic information and which
`enables information to be input directly into the CPU
`via the screen. The digitized screen preferably has an
`electromagnetic digitizer 37 controlled by digital con-
`trol logic 38, although a touch overlay digitizer screen
`could also be used with the present invention. Soft-
`ware-based prompts and graphics can facilitate the
`information input on the screen. A TFT backlit screen
`appropriate for the present invention is available from
`the IBM Corporation with the ThinkPad 700T™, al-
`though other types of digitized screens could be used
`with the present invention.
`The flat panel display 12 for the pen-based com(cid:173)
`puter can be used in a number of orientations. For ex(cid:173)
`ample, the flat panel display can be supported on a
`base or on display legs as will be described below, or
`can be held by hand or in a lap. In any case, the flat
`panel display can be rotated into either a "portrait" ori(cid:173)
`entation, in which the screen is oriented vertically
`(Figures 1 ,3); or rotated into a "landscape" orienta-
`tion, in which the screen is oriented horizontally (Fig-
`ures 2,4 ). The different orientations of the pen-based
`computer of the present invention will be discussed
`in more detail below.
`With reference to Figure 7, the electronics fort he
`pen-based computer preferably include a 486SLC/50
`based central processing unit (CPU) 39 having up to
`16MB memory 40 for executing instructions and ma(cid:173)
`nipulating data; solid state mass storage system 41
`having a removable 60MB memory card, such as
`found in the IDE Series marketed by Sun Disk Corp.;
`and an audio subsystem 42 using an IBM M-wave dig-
`ital signal processor. The CPU is interconnected to
`the flat panel display through the customary buffers,
`busses, clocks and latches (see, e.g., Figure 7). Disk
`drive(s) 43 can be incorporated into the electronics if
`necessary. Further, a remote power source 44 and
`control45 (e.g., an AC power source through an input
`46), can be included to power the CPU and disk
`drives; or a rechargeable battery pack 47 (and sub-
`battery 48) can be included with the computer for
`portable use. Such power supplies are conventional
`and well known to those skilled in the art. By way of
`example, a preferred electronic package of the type
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`5
`
`described above is found in the IBM ThinkPad
`700T™. Further, the interested reader is referred to
`Arnold, et al, U.S. Patent No.5, 142,626, for "Personal
`Computer with Removable Media Identification"; and
`W. Rosch, "TheWINN Rosch Hardware Bible", Simon
`& Schuster, Inc., NY, NY (1989) for disclosures of the
`electrical components of a computer. However, the
`electronics described above are only exemplary in
`nature and can be modified depending on the partic(cid:173)
`ular speed and power considerations of the computer.
`For display on the flat panel display 12, the elec(cid:173)
`tronics include a video RAM 49 with 512K bytes. The
`addresses stored in the video RAM can be accessed
`in different ways to provide user-defined output, as
`will be described in detail below. Typically the ad(cid:173)
`dresses are accessed to provide a display which, in
`the case of text, reads from left to right and top to bot(cid:173)
`tom when the flat panel display is in a portrait orien(cid:173)
`tation (vertically aligned such as illustrated in Figure
`1 ). However, the addresses in the video RAM can be
`changed such that the output is displayed from bot(cid:173)
`tom to top and left to right. The display will then have
`the correct alignment if the flat panel display is rotat(cid:173)
`ed into a landscape orientation (horizontally aligned
`such as in Figure 2). By having the output of the video
`RAM changeable relative to the axis of the computer,
`the housing can be rotated into different orientations
`with the display maintaining correct alignment for
`proper viewing.
`The electronics for the computer further include
`a mechanical switch 50 which accesses the video
`RAM to select the output of the video RAM. The
`switch 50 can be located at the opposite corner 52 of
`the upper surface from the flat panel display and can
`be manually manipulated to change the display on the
`flat panel display for proper viewing in any of the
`above-mentioned orientations. As illustrated in more
`detail in Figure 8, the mechanical switch 50 preferably
`includes five position buttons: left button 53, right
`button 54, up button 55, down button 56 and reset/de(cid:173)
`fault button 57, which are each accessible from the
`outer surface of the housing.
`The mechanical switch 50 is located over a print(cid:173)
`ed circuit board 58 to provide a digital output to the
`CPU and to "rotate" the screen display if necessary.
`The circuit board can be incorporated into a switch
`card 50 in the electrical layout (see Figure 7), or at an(cid:173)
`other appropriate location. As will be described be(cid:173)
`low, each position button 53-56 can be manually ma(cid:173)
`nipulated to change the orientation of the screen dis(cid:173)
`play to align the display with a certain axis of the com(cid:173)
`puter, while the reset/default button 57 resets the dis(cid:173)
`play to a program-defined alignment (e.g., a land(cid:173)
`scape orientation for a spreadsheet task), or in the
`case of a mercury switch, prevents the rotation of the
`screen display if desired.
`Alternatively, it is also within the scope of the
`present invention to provide a switch mounted within
`
`HTC Exhibit 1005
`
`

`

`9
`
`EP 0 598 547 A2
`
`10
`
`the housing of the computer. Such a switch could be
`e.g., a mercury switch (not shown) having a ring(cid:173)
`shaped frame with four recesses. As the orientation
`of the computer is changed, the mercury flows into a
`particular recess in the frame and outputs a position
`signal. The position signal indicates the orientation of
`the computer so that the display can be aligned ap(cid:173)
`propriately.
`With respect to the mechanical switch 51, as il-
`lustrated in Figure 9, the position buttons 53-57 are
`pulled down to ground by pull-down resistors 158-161
`normally causing the output of2-way AND gates 162-
`165 to be low. The D-Latches 166-169 are reset with
`the SYSTEM RESET 170 atthe power on time. Con-
`sequently, the outputs of D-latches 166-169 are reset
`to low level, 0. The output of four way OR gates 175
`is, therefore, 0 enabling the AND gates 162-165.
`While the outputs of four D-latches 166-169 are low,
`if any one of the position buttons 53-57 is pressed,
`the output of the corresponding 2-way AND gates
`162-165 will become high and clocks the correspond-
`ing D-latches 166-169. Since the D input of these D(cid:173)
`latches 166-169 is pulled up high via a pullup resistor
`176, the output of the corresponding D-latches 166-
`169 becomes high. This event will cause -SWIRQ 177
`to go active low through an open collector inverter
`178 causing an interrupt to the CPU. At the same
`time, the very same output of the D-latches 166-169
`will cause the 2-way AND gates 162-165 to be dis-
`abled outputting O's. This locks up any further inputs
`from the position buttons until the D-latches are
`cleared either by CPU via SWCLR signal179 from D-
`latch 180 or by pressing RESET SWITCH 181.
`Once the CPU is interrupted, the CPU will read
`the outputs on D ?! -D3 (182-185, respectively) by ac-
`tivating -SWREAD 186 (a decoded read probe).
`When -SWREAD is low, the tri-state buffers 187-190
`are enabled; while when -SWREAD is high, the out-
`put will be tri-state, regardless of the input to the buf-
`fers. If more than one bit is set to 1 by pressing more
`than one position buttons, the CPU can either discard
`the input and report an error message to the user, or
`use one of the position buttons as an input. For ex(cid:173)
`ample, if the position buttons 55 and 54 are pressed
`together at the same time by mistake, the software
`can default to less angle of rotation, or can return an
`error message. With a locking mechanism, such a sit(cid:173)
`uation cannot occur in most cases.
`Figure 10 shows the flow chart of the CPU proc-
`ess once the interrupt (on -SWIRQ) is detected.
`When CPU finds that one of these four bits is turned
`on, it computes the rotation angle using an equation:
`Rotation Angle = New Position Current Position.
`The CPU then assigns the new position as the cur-
`rent position. Using the equations shown on Figure
`11, the address of video data will be translated. This
`is possible since the one picture element (PIXEL) of
`this system is 8 bit similar to XGAand the video data
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`6
`
`is stored in a contiguous memory. Since IBM non(cid:173)
`portable desktop personal computers reserve only
`128K bytes of memory locations for video memory
`address, only 128K bytes of memory wi II be visible to
`the system out of 409600 bytes of the video buffer.
`Using this fact, the starting address of the video
`memory can be dynamically changed. In case the
`button 53 or 56 is selected, the starting offset ad(cid:173)
`dress should be 19000 hex. On the other hand, if the
`button 55 or 54 is selected, the starting offset ad(cid:173)
`dress should be 0. In case button 53 or 56 is selected,
`the display should be able to shift the window area so
`that it can show hidden area.
`Once the rotating task is completed, the CPU will
`write 1 to the SWCLR register 179 in D-latch 180 by
`activating -SWWRITE 191 (a decoded write probe) in
`Figure 9. This will activate SWCLR 179 to 1 causing
`a clear to D-latches 166-169. Consequently, this
`event unlocks the 2-way AND gates 162-165 so that
`the logic can accept the next user input. The CPU
`also has to make sure to write 0 after the clear oper(cid:173)
`ation is finished in order to accept the next input. In
`case the user wants to unlock the AND gates 162-165
`or deactivate the SWCLR signal, the user can press
`the RESET SWITCH 180. When the RESET SWITCH
`is pressed, an R-C (Resistor-Capacitor) circuit 192,
`194 will delay the charging of the capacitor 194 pro(cid:173)
`viding a low level pulse to the input of a Schmitt trig(cid:173)
`gered inverter 196. This event will cause a low pulse
`at the output of the three way NOR gate 198 and a
`low level pulse on the output of 2-way NOR gate 199
`to D-latch 180, clearing all D-latches 166-169, 180 on
`Figure 8.
`The housing 10 fort he computer is ergonomically
`designed to provide comfortable use for finger and
`stylus writing in a normal manner. In particular, refer(cid:173)
`ring again to Figures 1-6, the rhombohedron shape of
`the housing allows a writer to rest the palm of the
`hand on the angled side and lower edge surfaces 26,
`28 for comfort during text, data, and information en(cid:173)
`try. As described previously, for a right-handed writer,
`the computer will be in at least one orientation and
`the user will have a palm restforthe right hand, while
`f