Multi-programmed data processing system with facility for inspecting
Contents
1. 4 and are state diagrams of an application handler mechanism OVERALL VIEW OF THE SYSTEM Referring to FIG 1 the system is based on a micro processor 10 which acts as the central processing unit In the present system the microprocessor is a Motorola MC68008 operating at a clock rate of 7 5MHz The microprocessor 10 is connected to a bus 11 which carries data addresses and control signals 4 713 656 3 The bus 11 is connected to a 128K byte ROM 12 a 128K byte dynamic RAM 13 and a 2K byte static RAM 14 The static RAM is provided with a back up battery 15 so that data in it is preserved when the system is powered down The bus 11 is also connected to a socket 16 for receiving a plug in ROM module 17 This can be used to supply optional software packages as required The bus 11 is also connected to an input output con troller 18 a display controller 19 and a telephone and keyboard controller 20 The input output controller 18 controls a pair of magnetic tape drive units 21 only one shown of the kind using endless loop magnetic tape cartridges as removable storage media The unit 18 also controls a printer 22 The display controller 19 is con nected to a visual display unit 23 having a CRT screen for viewing by the system user The telephone and keyboard controller 20 supervises a keyboard 24 tele phone handset 25 and two telephone lines 26 The keyboard contains all the usual keys arranged in the conventional QWERTY l2. causing that program to be executed 6 A method of operating a data processing system comprising processing means a display screen and a keyboard the method comprising the steps a executing a plurality of programs concurrently in the processing means b maintaining in respect of at least some of the programs display screen data indicating the cur rent status of the program c maintaining a review menu containing a list of those programs currently having display screen data available d in response to operation of a predetermined key on said keyboard displaying the review menu on the screen e in response to operation of a further key on said keyboard while the review menu is being dis played selecting one of the programs listed on the review menu and causing the display screen data of the selected program to be displayed on the screen for as long as said further key is held and f in response to release of said further key restoring to the screen the information that was being dis played prior to operation of said predetermined key t amp
3. hand it is transient it is terminated In either case the next action of the application handler is to consult the pro gram table to determine how many applications are waiting to go into the foreground mode If no application is waiting the application handler causes the top level menu to be displayed FIG 3 inviting the user to select a new application If there is just one application waiting that application is put into the foreground mode Finally if there is more than one application waiting the application handler constructs a special resume menu which lists all the applications waiting to be allocated to the foreground mode This menu is displayed allowing the user to choose one of those applications by pressing an appropriate key The selected application is then put into the foreground mode It can be seen that the START and RESUME keys provide an efficient and convenient mechanism for the user to select new applications to be run and to switch them between the foreground and background modes For example if the user is running one program and wishes to break off to perform another more urgent task it is only necessary to press the START key and then to make the appropriate selection from the top level menu which is displayed When the user wishes to return to the original application program it is only necessary to press the RESUME key and the applica tion will be restored to the foreground mode If there is mor
4. GROUND PROGRAM BACKGROUND TO THE INVENTION This invention relates to data processing systems The invention is particularly although not exclusively con cerned with data processing systems of the kind usually referred to as personal computers Such computers are normally used by non computer oriented persons or inexperienced users It is therefore desirable that they should provide functions which are natural in their operation and easy to use with little or no training and minimal reference to documentation Such a system may be designed to allow a plurality of different application programs to be executed concur rently For example it is possible to run a word process ing program while at the same time running a program which is accessing a remote database Normally a per sonal computer is provided with just a single screen to keep the cost to a minimum In order to view the states of the different applications programs it has been pro posed to use a windowing technique in which the screen is divided into a number of separate areas each of which is allocated to a different program Thus the user can for example refer to data retrieved from the database while using the word processing program However the windowing technique is inconvenient since it introduces extra complexity in the system and restricts the screen area available to each program One object of the present invention is to provide a way of dealing with
5. IEW key and which may contain different infor mation from that currently displayed by the application The REVIEW mechanism may also allow inspection of review screens containing data from applications which are not currently active i e which are dormant For example a telephone directory application may remember the most recently selected entry and the 4 713 656 9 REVIEW mechanism may allow this to be viewed even when the telephone directory application is dormant For this purpose when constructing the review menu the application handler considers not only those appli cations which are active but also those that are not active but may have associated stored data which is reviewable This is achieved by an additional table maintained by the application handler in which appli cations can declare the existence of such data What is claimed is 1 A data processing system comprising a means for executing a plurality of programs con currently b a display screen for displaying data associated with any one of the programs c means for allocating any one of the programs to a foreground mode in which it is allowed to access the display screen and for allocating the other pro grams to a background mode in which they are not allowed to access the display screen d means for maintaining in respect of each of the programs currently in the background mode dis play screen data indicating the current status of that progr
6. STRACT A data processing system that can execute a plurality of programs concurrently and has a display screen for displaying data associated with any one of the pro grams Each program maintains display screen data indicating the current status of the program The system maintains a REVIEW menu containing a list of the programs that have display screen data available When a REVIEW key is pressed the REVIEW menu is dis played By pressing a further key one of the listed pro grams can then be selected and its display screen data is displayed on the screen When the key is released the information that was being displayed prior to operation of the REVIEW key is restored to the screen A RE SUME menu lists programs that are currently in a back ground mode and can be called up by pressing a RE SUME key allowing one of those programs to be put into a foreground mode in which it has access to the screen Another menu lists programs that are available for execution and can be called up by pressing a START key allowing one to be selected for execution 6 Claims 5 Drawing Figures US Patent Dec 15 1987 Sheet 1 of 5 4 713 656 21 15 MAGNETIC TAPE BATTERY DRIVE 12 14 STATIC RAM E PRINTER OUTPUT a CONTROLLER MODULE is 11 16 PROCESSOR 19 20 BATTERY TELEPHONE Picea amp KEYBOARD CONTROLLER oe TELEPHONE 23 26 VISUAL DISPLAY KEYBOARD LINES UNIT 5 TELEPHONE HANDSET FIG US Patent Dec 15 1987 She
7. United States Patent 5 Cliff et al 4 713 656 Dec 15 1987 11 Patent Number 45 Date of Patent 54 MULTI PROGRAMMED DATA PROCESSING SYSTEM WITH FACILITY FOR INSPECTING STATE OF BACKGROUND PROGRAM John F Cliff Bracknell Robert R Walton Woking both of England International Computers Limited London England 21 Appl No 789 323 22 Filed Oct 21 1985 30 Foreign Application Priority Data 75 Inventors 73 Assignee Nov 10 1984 GB United Kingdom 8428443 A casiceicteeetia ne GO6F 3 14 52 U S Cl 340 723 364 900 340 724 340 721 340 712 58 Field of Search 364 200 MS File 900 MS File 340 707 709 712 714 798 799 723 721 724 747 56 References Cited U S PATENT DOCUMENTS 4 079 449 3 1978 Mercurio et al 0 364 200 4 200 869 4 1980 Murayama et al 340 723 4 484 302 11 1984 Cason et al ccscereceersreees 364 900 4 550 386 11 1985 Hirosawa et al ve 364 900 4 556 954 12 1985 Advani et al 364 900 4 586 035 4 1986 Baker et al 340 712 4 611 306 9 1986 Crehan et al 364 900 4 641 262 2 1987 Bryan et al 364 900 4 670 752 6 1987 Marcoux cscecesertseerreee 340 721 OTHER PUBLICATIONS Macintosh User s Manual 1983 pp 13 41 54 75 87 90 99 108 Primary Examiner Gary V Harkcom Assistant Examiner Randy W Lacasse Attorney Agent or Firm Lee Smith amp Zickert 57 AB
8. also has the option of pressing a different key or combination of keys to cause the selected display to be held on the screen until it is spe 35 40 45 55 65 2 cifically released e g by means of a further key opera tion The use of menus to guide the inexperienced user is known in itself However in conventional systems the menu called up by the user is generally a high level menu showing all the available programs of the system It is therefore usually necessary to display further sub sidiary menus listing the options in more detail before the user can make the final choice In contrast in the present system the menu which is displayed as a result of pressing the REVIEW key is one specially con structed for this purpose and contains only those pro grams which currently have displays available for view ing In a personal computer it is desirable for the user to be able to initiate new application programs at will as the need arises with the minimum of complication and effort In the system described herein this facility is provided by means of a further manually operable key the START key which when operated and causes the screen to display a menu indicating available appli cation programs allowing one of those programs to be selected for execution by the system Preferably at any given time one of the programs is allocated to a foreground mode in which it is allowed to access the screen the othe
9. am e means for maintaining a review menu containing a list of those programs currently having display screen data available f a manually operable review key g means responsive to operation of the review key to cause said review menu to be displayed on the screen in place of information from the program currently in the foreground mode h manually operable selection means i means responsive to operation of said selection means when the review menu is being displayed to select one of the programs listed on that menu and to cause the display screen data of the selected program to be displayed on the screen for as long as said selection means is operated and j means responsive to release of said manually oper able selection means to restore to the screen the information from the program currently in the foreground mode 2 A system according to claim 1 wherein the manu 10 15 20 25 30 35 ally operable selection means comprises a plurality of 45 further keys and wherein the means responsive to oper ation of said selection means is responsive to operation of a single one of said further keys to select one of the programs listed on the review menu and to cause the display screen data of the selected program to be dis played on the screen for as long as that further key is held 3 A system according to claim 2 further including means responsive to operation of a different one or a combination of sai
10. ayout and also includes special system keys labelled START RESUME and REVIEW the function of which will be described in detail later The keyboard also includes a numeric key pad of the type used in push button telephones The controller 20 uses this keypad in conjunction with the handset 25 and telephone lines 26 to allow the user to make and receive telephone calls in the conventional manner It also allows the system to transmit and re ceive data over the lines 26 The controller 20 continuously monitors the key board 24 and whenever it detects a change of state of any of the keys it produces an interrupt signal to the processor 10 The controller 20 has a back up battery 27 which allows the voice telephony function to con tinue even when the system is powered down Multi tasking The system is designed to allow multi tasking i e a number of different tasks or processes herein referred to as activities can be executed concurrently Actu ally the processor 10 can only execute one activity at a time and multi tasking is achieved by rapidly switching between the different activities so as to give the impres sion that they are all being executed simultaneously Scheduling and co ordination of the activities is car ried out by an item of system software referred to as the kernel which runs on the processor 10 The kernel also provides low level management of the various parts of the system including handling of in
11. d further keys for selecting one of 55 the programs listed on the review menu and causing the 65 10 display screen data of the selected program to be dis played on the screen and to be maintained on the screen after that key or combination of keys has been released 4 A system according to claim 1 including a means for maintaining a resume menu containing a list of programs currently in the background mode b a manually operable resume key c means responsive to operation of the resume key for causing the program currently in the fore ground mode to be reallocated to the background mode and causing the resume menu to be displayed on the screen and d means responsive to operation of the manually operable selection means while the resume menu is being displayed to select one of the programs listed on that menu and to allocate the selected program to the foreground mode 5 A system according to claim 1 including a means for maintaining a start menu containing a list of programs not currently being executed but available for execution b a manually operable start key c means responsive to operation of the start key for causing the start menu to be displayed on the screen in place of any information currently dis played there and d means responsive to operation of the manually operable selection means while the start menu is being displayed for selecting one of the programs listed on the start menu and
12. e than one application to which the user can return he is presented with a menu from which to choose REVIEW key The REVIEW key provides a mechanism which allows the user to make an unpremeditated inspection of data associated with an application The REVIEW action has no permanent effect on the application which is reviewed nor on any other application Each reviewable application contains a section of code which maintains a set of data referred to as the review screen which is available for inspection during the REVIEW action The choice of what data to in clude in the review screen is determined by the designer of the application typically it will be the current screen of the application i e the one which would be dis played if the application were in the foreground mode It might instead be a status report on the job being handled by the application Referring to FIG 5 when the REVIEW key is pressed the application handler consults the program table to find which application is currently in the fore ground mode It then suspends that application from the foreground so that it stops using the keyboard and screen This applies to both extended and transient ap plications the REVIEW key does not cause a transient 15 20 25 35 40 45 50 55 65 8 application to terminate The application handler then causes a special REVIEW menu to be displayed This lists all the applications which currently have revie
13. es tempo rary entries in the program table for them The program table is updated by the application han dler whenever it makes a scheduling decision e g allo cating the foreground mode to an application and by the applications when they make a call to the applica tion handler to notify it of a change of state e g re questing to be put into the foreground mode FIGS 3 4 and 5 show a state diagram of those parts of the application handler relevant to the present inven tion START key Referring to FIG 3 when the START key is pressed this is detected by the keyboard controller 20 which causes an interrupt in the processor 10 This is detected by the kernel which informs the application handler by setting one of the bits in its event register The application handler then consults the program table to find which application is currently in the fore ground mode and whether it is extended or transient If it is an extended application the application handler sends it a message instructing it to stop using the screen and keyboard Alternatively if the application is tran sient the application handler sends it a message instruct ing it to terminate In either case the application handler receives from the application an acknowledgement that it has stopped using the screen and keyboard The application handler then uses the screen to display a top level menu listing all the applications that are currently available for
14. et 2 of 5 4 713 656 30 FOREGROUND MODE TERMINATED SUSPEND FROM FOREGROUND START DORMANT 31 BACKGROUND MODE FINISHED REQUIRE USE OF SCREEN KEYBOARD WAITING FOR FOREGROUND FOREGROUND ALLOCATED FIG2 US Patent Dec 15 1987 Sheet 3 of 5 4 713 656 FIND FOREGROUND APPLICATION EXTENDED TRANSIENT EXTENDED TRANSIENT SUSPEND FROM FOREGROUND Q TERMINATE DISPLAY TOP LEVEL MENU KEY OPERATED START SELECTED APPLICATION ALLOCATE FOREGROUND Fic 3 U S Patent Dec 15 1987 Sheet 4 of 5 4 713 656 FIND FOREGROUND APPLICATION EXTENDED OR TRANSIENT EXTENDED TRANSIENT SUSPEND FROM TERMINATE FOREGROUND FIND HOW MANY MORE THAN ONE APPLICATIONS WAITING FOR FOREGROUND DISPLAY TO RESUME MENU ALLOCATE Fig 3 FOREGROUND OPERATED ALLOCATE SELECTED APPLICATION TO FOREGROUND fic US Patent Dec 15 1987 Sheet 5 of 5 FIND FOREGROUND APPLICATION SUSPEND FROM FOREGROUND DISPLAY REVIEW MENU RESUME KEY START KEY FUNCTION KEY OTHER KEY WAKE UP REVIEW ACTIVITY WAKE UP REVIEW ACTIVITY TERMINATE REVIEW ACTIVITY RE ALLOCATE FOREGROUND 4 713 656 4 713 656 1 MULTI PROGRAMMED DATA PROCESSING SYSTEM WITH FACILITY FOR INSPECTING STATE OF BACK
15. hich does not require the use of the screen and keyboard for example it can continue to send and receive data over one of the telephone lines However if it reaches a stage where it requires to interact with the user before it can proceed any further it makes a request to use the screen and keyboard and then goes into a waiting state The system user can choose which of the applications is to be in the foreground mode by use of the START and RESUME keys as will be described later Applications are classified as extended or transient Transient applications are typified by relatively short access to the screen and keyboard to perform single updates or enquiries on data held in the system and they are likely to be invoked at unpredictable times while longer applications are running An example of a tran sient application is one which provides a telephone directory service where the user may wish to access the directory from time to time to look up a telephone number or to update an entry When the user selects a new foreground application by operation of the START or RESUME keys the assumption is that he has finished with the transient application and so it is terminated This is a very convenient feature since it allows the user to terminate such applications without the need for an explicit command 4 713 656 5 Extended applications are typified by lengthy user interactions by way of the screen and keyboard The user may wish t
16. ith the application handler by means of the START RESUME and REVIEW keys as described below The application handler makes use of a table referred to as the program table which is held at a predeter mined location in the RAM 13 This contains an entry for each application program currently known to the system Each entry contains a the name of the application 10 15 20 25 30 35 45 50 55 65 b its address in ROM or RAM c an activity identifier which is used by the kernel to identify the activity d status flags indicating the status of the application These include flags to indicate whether or not the application has requested to be put into the fore ground mode whether the foreground has been allo cated to it and whether this is an extended or tran sient application When the system is initially powered up the applica tion handler puts a number of fixed entries into the program table corresponding to those applications which are supplied as standard features of the system The application handler then scans all addresses at which an application program might exist whether in the ROM 12 or the plug in ROM modules 17 When ever it finds an application program at any of these addresses it makes a corresponding entry into the pro gram table When requested by the user it also reads the names of any application programs supplied on mag netic cartridge in the tape drive 21 and mak
17. o break off to perform other more urgent tasks while retaining the ability to return to the extended application Thus when the user selects a new foreground application by means of the START and RESUME keys the extended application is not termi nated but is simply put into the background mode relin quishing the screen and keyboard until it is selected again as the foreground application In the meantime it can continue processing if appropriate Some applications may be wholly transient or wholly extended However some applications may be some times transient and sometimes extended For example a teletext program may be extended when handling con nections to a teletext computer over the telephone line but transient when displaying stored pages captured during a previous connection Referring to FIG 2 this is a state diagram of a typical application program State 30 represents the foreground mode in which the application is active and has access to the screen and keyboard If the application is termi nated it immediately stops using the screen and key board It may however continue running to complete any data transfers it may have been performing so as to leave the data in a consistent state It then goes into the dormant state 31 The application will remain in this state until it is restarted by use of the START key It will then request to be allowed to use the screen and keyboard and when this request is granted goe
18. r programs all being allocated to a background mode in which they are not allowed to access the screen The system conveniently includes a further manually operable key the RESUME key which when operated causes the current foreground program to be put into the background mode and causes the background program if any to become the new foreground program in its place or if there is more than one background program currently waiting to use the screen displays a menu indicating which programs are so waiting Thus it can be seen that the START and RESUME keys provide a convenient mechanism to allow the user to initiate new programs and to return to a previous program as required Preferably the programs are divided into two cate gories extended and transient and the operation of the START or RESUME key causes the current fore ground program to be automatically terminated if it is transient but allows that program to continue running as a background program if it is extended This is conve nient since it means that in the case of a transient pro gram the user does not have to specifically terminate it when he switches to another program BRIEF DESCRIPTION OF THE DRAWINGS One data processing system in accordance with the invention will now be described by way of example with reference to the accompanying drawings FIG 1 is a block diagram of the system FIG 2 is a state diagram of a typical application program FIGS 3
19. run ning on the system It then waits for another key to be pressed The user may select any of the applications listed in the top level menu by pressing the key indicated by the menu For example a calculator program may be se lected by pressing the 6 key This is detected by the kernel and notified to the application handler The ap plication handler then requests the kernel to start up the selected application As soon as the selected application starts running it sends a message to the application handler requesting permission to go into the foreground mode and also informing the application handler whether it is cur rently extended or transient The application handler updates the program table and sends a message back to the application telling it that it has been allocated to the foreground mode 4 713 656 7 Alternatively when the top level menu is displayed the user may press a key which selects a subsidiary menu listing further applications This will lead the application handler into further states not shown which display the subsidiary menu and start the selected application RESUME key Referring now to FIG 4 when the RESUME key is pressed the application handler again consults the pro gram table to find which application is currently in the foreground mode and whether it is extended or tran sient If the foreground application is extended it is suspended from foreground mode If on the other
20. s into the foreground mode If the application is suspended from the foreground mode by use of the START or RESUME key it imme diately stops using the screen and keyboard If it is an extended application it then enters the background mode state 32 in which it continues to run without using the screen or keyboard In the case of a transient application suspension from the foreground mode causes the application to go into the dormant state If the application completes its processing in the background mode it terminates and goes into the dor mant state 31 However if it reaches a stage where it requires to use the screen or keyboard it goes into a suspended state 33 waiting for the use of the screen and keyboard to be allocated to it When they are allocated the application returns to the foreground mode 30 Application handler The applications programs are supervised by a mech anism referred to as the application handler The appli cation handler may be a systems program which runs on the processor 10 and is treated as an activity by the kernel being multi tasked with the other activities Alternatively the application handler could be imple mented wholly or partly by means of hardware The application handler acts as a high level sched uler allowing the user to decide which applications are to be run and which of these is to be the foreground application with access to the screen and keyboard The user interacts w
21. t program in this way the function key is pressed along with key 3 on the keypad In this case there is no need to hold down the keys they can be released immediately The review activity continues to run and hence the review screen continues to be displayed even when the keys are released This allows the user to inspect the review screen at leisure and to perform other actions such as using the telephone facil ity When the user wishes to return to the original appli cation he presses the RESUME key which causes the application handler to terminate the review activity The application which was interrupted by the RE VIEW sequence is then restored to the foreground Alternatively the user can press the START key which causes the top level menu to be displayed FIG 3 Similarly while the review menu is being displayed the user can press the RESUME key which causes the original application to be restored immediately without viewing any review screen Alternatively he can press the START key to cause the top level menu to be displayed The use of the START key during the REVIEW operation as described in the preceding two para graphs has the same effect on the interrupted applica tion as at other times i e the application becomes sus pended or is terminated depending on whether it is extended or transient The current foreground application may itself have a review screen which can be displayed by use of the REV
22. tems are well known in the art and so it is not necessary to describe the kernel in any greater detail Application programs The user of the system will require to run one or more application programs These may either be sup plied with the system or written by the user or pur chased from a third party Application programs may include for example programs for word processing spread sheet analysis data base management and mes sage handling These application programs can be pro vided as standard items in the ROM 12 or can be sup plied as options in the form of ROM modules 17 Alter natively they can be supplied on magnetic tape car tridges and loaded into the RAM 13 from the tape drive unit 21 when required Each application program is treated by the system as one or more activities which are scheduled by the kernel as described above Hence several application programs can be active concurrently in the system In general application programs require to interact with the system user by means of the display screen 23 and keyboard 24 However only one of the currently active applications is allowed to use the screen and keyboard at any given time This is referred to as the foreground application and is said to be running in fore ground mode Any other currently active applications are referred to as background applications running in background mode An application in background mode can continue to perform processing w
23. terrupts from the controllers 18 19 20 Each activity has its own stack and register values which are held in an area of the RAM 13 allocated to that activity When the kernel selects an activity to run it loads the register values of that activity into the actual registers of the processor 10 and then passes control of the processor to that activity The activity then runs until either a it completes its processing task b it reaches a point where it must wait for a response from some other part of the system or c an interrupt signal is received The interrupt may be from one of the controllers 18 19 20 requesting some service or may be a time out interrupt indicating that the current activity has used up its time allocation When any of these events occurs the kernel takes over again examines any interrupts 10 20 25 30 35 45 50 55 60 65 4 present and decides which activity should be selected next Each activity has a 32 bit event register held in its allocated area of RAM Any activity can request the kernel to set one of the bits in the event register of another activity When an activity runs it can test the bits of its event register and can take different actions according to their settings for example it can decide to wait until a bit has been set before taking a particular action This provides a means for communication be tween activities Control programs for multi tasking sys
24. this problem which is more conve nient than the windowing technique and which is suit able for use by the inexperienced user SUMMARY OF THE INVENTION According to the invention there is provided a data processing system arranged to execute a plurality of programs concurrently and having a display screen for displaying data associated with any one of the pro grams characterised in that a each of the programs maintains display screen data indicating the current status of that program b the system maintains a review menu containing a list of those programs having display screen data cur rently available c the system has a manually operable review key which when operated causes the review menu to be displayed on the screen in place of any information currently displayed there and d the system has manual selection means operable when the review menu is being displayed to select one of the programs listed on that menu and to cause the display screen data of the selected program to be displayed on the screen It can be seen that the REVIEW key thus allows a quick unpremeditated inspection of the state of any selected program Preferably when the review menu is displayed the user can select one of the programs listed in the menu by pressing a single key and the display screen data of the selected program is then displayed on the screen only for as long as the user holds down that key How ever the user preferably
25. w screens available for inspection The user can select one of these screens in two ways The first way is to press and hold down a single key corresponding to the desired review screen as indicated on the review menu For example the review screen for the spread sheet program may be selected by pressing the 3 key This causes the application handler to send a wakeup message to a special activity referred to as the review activity This activity then runs and causes the review screen of the selected application to be dis played on the screen of the display unit Meanwhile the application handler checks every tenth of a second whether the key has been released When the user releases the key the application handler sends a terminate message to the review activity causing it to go back into the dormant state Finally the application handler puts the application which was interrupted by the REVIEW sequence back into the foreground mode In summary it can be seen that the review screen is displayed for as long as the user holds down the se lected key As soon as the key is released the original application is returned to the screen The other way of selecting a review screen from the review menu is to press the Function key on the keyboard this is a standard key on conventional key boards along with the numeric key on the keypad cor responding to the desired selection For example to select the spread shee
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