Patent Document

[0001]    This is a non provisional application of provisional application serial No. 60/248,101, filed Nov. 13, 2000 by Ortlam et al. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to a display system for displaying images representing real-time data simultaneously with images representing non-real-time data.  
         BACKGROUND OF THE INVENTION  
         [0003]    Systems for displaying images representing real-time data have a long history. For example, systems have long existed for displaying a waveform image representing real-time physiological data such as electrocardiogram (ECG) data. More recently, systems have been developed for simultaneously displaying multiple images representing respective real-time data. For example, current ECG systems can simultaneously display all 12 waveforms of a full 12 lead ECG. U.S. Pat. No. 6,104,948, issued Aug. 15, 2000 to Bogart et al., discloses a system for receiving a plurality of physiological real-time data from different sources, such as ECG, electroencephalogram (EEG), skin conductance information, oculometer derived look-point data, and skin temperature. The system also receives other real-time data such as cardiac cine-loop video. The system then simultaneously and synchronously displays a composite image containing the respective images representing all of the received real-time data. The composite image may be recorded utilizing a scan converter on a video tape recorder for future study.  
           [0004]    Systems for simultaneously displaying images representing respective non-real-time data also exist. For example, computer windowing operating systems, such as UNIX X-windows, Apple Macintosh and Microsoft Windows permit programs to be written for displaying multiple images representing respective non-real-time data. For example, U.S. Pat. No. 5,956,013, issued Sep. 21, 1999 to Raj et al. discloses a Microsoft Windows based system for receiving prerecorded ECG data from, e.g. a Holter heart monitor, and displaying a first image of a waveform representing several seconds of ECG data, and simultaneously displaying a second image of a selected number (e.g. one to five) of heartbeat waveforms atop each other aligned on their R waves.  
           [0005]    Further systems exist for simultaneously displaying images representing real-time data and images representing non-real-time data. For example, computer systems operating under the control of the above mentioned windowing operating systems have been designed to include a real-time data collection device, and images representing the gathered real-time data have been displayed simultaneously with images representing non-real-time data. U.S. Pat. No. 4,845,653, issued Jul. 4, 1989 to Conrad et al. discloses a system in which a plurality of two parameter data fields are simultaneously displayed representing respective views of the same multi-parameter data. This data may be displayed in real-time as it is received. A user may define an outline enclosing an area in one of the data fields, and the data points corresponding to those within that area are highlighted in the other data fields. Further non-real-time information, derived from the enclosed data points, may also be displayed.  
           [0006]    One skilled in the art will understand that the computer windowing operating systems, described above, make it relatively simple to design and implement a program to simultaneously display real-time and non-real-time data. Consequently, many programs have been written to perform a wide variety of very desirable tasks for these operating systems. One skilled in the art will also understand that such operating systems are not reliable and will often require restarting, resetting or rebooting, particularly when executing a program or multiple programs including multiple tasks or threads. However, it is always desirable for systems to operate with high reliability. In some applications, such as medical monitoring equipment, it is imperative that the system operate with the highest possible reliability. For example, for an ECG monitor, the display of the waveform images representing the ECG data must never be interrupted, and further must proceed with a minimum latency time between receipt of the real-time ECG data and the display of that data.  
           [0007]    One skilled in the art will understand that display of non-real-time data simultaneously with display of the real-time (e.g. ECG) data would be useful. For example, a doctor analyzing a patient&#39;s real-time ECG display might desire to simultaneously display textual lab results for the patient, or an image of an X-ray, or data from the patient&#39;s chart, or even information from a pharmaceutical company&#39;s web site. The skilled practitioner will also appreciate the advantages provided by using a windowing operating system as the basis for such a system, such as familiarity of use, ease of programming and the availability of a wide variety of programs. Finally, the skilled practitioner will appreciate that, while display of non-real-time information is important and desirable, a malfunction in the non-real-time data display program (such as must be expected when using such windowing operating systems) must not be allowed to interrupt the display of the real-time ECG data under any circumstances. Thus, a system which permits simultaneous display of real-time and non-real-time data using existing windowing operating systems, but which does not permit malfunction in the display of the non-real-time data to interrupt the display of the real-time data is desirable.  
         BRIEF SUMMARY OF THE INVENTION  
         [0008]    In accordance with principles of the present invention, a method and apparatus for concurrently displaying respective images representing real-time data and non-real-time data operates by first receiving non-real-time data and receiving real-time data. A windowing operating system is executed for controlling the operation of an application program which is responsive to the non-real-time data, for conditioning a display device to display respective images representing the non-real-time data. A real-time display process is executed concurrently with, but independently from, the windowing operating system, for conditioning the display device to display respective images representing the real-time data concurrently with the display of the non-real-time data. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0009]    In the drawing:  
         [0010]    [0010]FIG. 1 is a block diagram of a computer system according to principles of the present invention; and  
         [0011]    [0011]FIG. 2 is a software architecture diagram illustrating an architecture according to principles of the present invention, executing on the processor for controlling the system;  
         [0012]    [0012]FIG. 3, FIG. 4 and FIG. 5 are screen diagrams illustrating images displayed by the system according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    [0013]FIG. 1 is a block diagram of a computer system  10  according to principles of the present invention. In FIG. 1, a processor  102  has a first bidirectional terminal coupled to a data storage device  104  and one or more further bidirectional terminals coupled to corresponding network interface circuits (NIC)  106 . Each NIC  106  is coupled to a corresponding network  114 . The networks  114  may include a real-time network, such as a patient area network with a required latency time of less than 200 ms from patient sensor to display, a ward area network with latency on the order of seconds, and/or a hospital network which has no real-time latency requirement. One or more of the networks  114 , most likely the hospital network, may also include a bridge (not shown) to a wide area network such as the internet. A source  108  of a user input signal is coupled to a first input terminal of the processor  102  and a source  110  of a real-time input signal is coupled to a second input terminal of the processor  102 . An output terminal of the processor  102  is coupled to an input terminal of a display device  112 .  
         [0014]    In operation, the processor  102  receives program code and data from the data storage device  104 . The processor  102  controls the operation of the system  10  under the direction of the received program code. The architecture of this program code will be described in detail below. In general, the processor  102  receives real-time data from the real-time data source  110  and/or the real-time network  114  and conditions the display device  112  to display images representing the real-time data. For example, the real-time signal source  110  and/or real-time network  114  could include an ECG module having electrodes intended to be connected to a patient. The signals from the electrodes are processed by the processor  102  which, in turn, conditions the display device  112  to display images representing a real-time 12 lead ECG. In accordance with medical monitoring system requirements, this real-time display has a maximum latency of 200 milliseconds from receipt of the data from the ECG module to display of that data on the display device  112  and must have the maximum practical reliability.  
         [0015]    The processor  102  further monitors the user input signals from the user input signal source  108 . The user input signals may be derived from, e.g. a keyboard and/or mouse (not shown) or any other input device. The processor  102  then controls the system  10  in response to the user input signals. These user input signals can control aspects such as size and location of the display of the real-time images, e.g. 12 lead ECG images, and/or selection and display of non-real-time data. For example, in response to identification information received from the user via the user input signal source  108 , a non-real-time application program is executed so that non-real-time data may be retrieved from specified files in the data storage device  104 , or from specified locations on the network  114 , e.g. patient chart data, lab results or X-ray images from the hospital LAN server or other data from the internet, via the NIC  106 . The controller  102  conditions the display device  112  to display images representing the retrieved non-real-time data and/or other data received from the user input signal source  108  on the display device  112  simultaneously with the images representing the real-time data from the real-time data source  110  and/or real-time network  114 . The processor  102  also controls the operation of the system  10  as a whole in response to user input signals from the user input signal source  108  in a manner to be described in more detail below.  
         [0016]    In a preferred embodiment, the processor  102  operates under the control of a windowing operating system, and in the illustrated embodiment, the windowing operating system is the Microsoft NT operating system. FIG. 2 is a diagram illustrating the architecture of the program code executed by the processor  102  to control the system  10 . An operating system (OS)  202  provides services for the rest of the software system  20  consisting of functions and data common to all other software modules which execute on the system  20 . For example, the message transmission system necessary for multiprocessing, and the graphics display interface, is administered in the OS  202 . In addition, processes and threads may be initiated and terminated, and memory may be allocated to and deallocated from a process and/or thread, in the OS  202 .  
         [0017]    Parameters related to the operation of the software system  20  are also maintained in the OS  202 . For example, data related to total processor usage; the length of the message queue for each process and thread; available memory; virtual memory page access faults; working set size and paging rate; a count of handles allocated to processes and threads; the proportion of processor time being used by each process or thread; the rate of data transmission on the network  114 ; and responsiveness of respective processes and threads to user input signals, among other things, may all be determined by and stored in the OS  202 . It is also possible for physical parameters of the hardware system  10  to be received by circuitry under control of the OS  202  and data related to these parameters to be stored in the OS  202 . For example, data such as central processing unit (CPU) chip temperature, power supply voltage, hard disk usage elapsed time, and hard disk storage free space, may be maintained in the OS  202 .  
         [0018]    In general, the program  20  is a three tiered architecture. The first tier is a common software architecture  204  which provides a software interface between application packages ( 206  and  208 ) and the OS  202 . The common software architecture  204  provides the application program interfaces (APIs) for the application programs. By providing APIs, the operating system simplifies the task of programming applications. Functions, such as requesting initiation of a thread or allocation of memory, are provided to the application programmers through simple function calls, all in a known manner.  
         [0019]    Common and specific application packages,  206  and  208 , form a second tier. Common application packages  206  refer to applications which are provided by the providers of the operating system. These are generally applications which are used by most or all of the users of the operating system. The common application packages  208  can include text editors, image viewers, HTML viewers (web browsers), etc. Furthermore, portions of these common application packages may be used by the specific application packages  208 . Specific application packages  208  are those providing special functions required by the system. In general, a single specific package  208  provides a desired special processing. The common and specific application packages,  206  and  208  receive operating system services via APIs in the common software architecture  204 , and generate images to be displayed on the display device  112  through a common human interface  210 . The human interface  210  forms a third tier. The human interface  210  is provided as a part of the operating system and provides another API for allowing common and specific application programs  206  and  208  to produce images on the display device  112 , all in a known manner.  
         [0020]    The portion of the software architecture  20  described so far is the standard architecture for non-real-time programs implemented on the Windows NT operating system. This portion of the software architecture executes as a single executable, calling for functions through the various APIs described above, spawning tasks and threads, and requesting and returning memory as required.  
         [0021]    In the illustrated embodiment, an additional process  212  receives the real-time ECG signals from the real-time signal source  110  and/or real-time LAN  114 , and processes the received real-time ECG signals to generate images for the display device  112  representing a 12 lead ECG corresponding to the received signals in a manner to be described in more detail later. The real-time display process  212  receives operating system services from the OS  202  only. It does not use services in the common software architecture  204  or the common human interface  210 . This process executes as a second executable, independent of, but coordinated with the non-real-time executable described above. In addition, the real-time process  212  is implemented as a single thread which processes data from receipt from the data source to generation of the display image, insuring minimum latency.  
         [0022]    The following operational parameters all relate to the Windows NT environment. Other windowing operating systems have similar parameters. In the illustrated embodiment, all non-real-time applications, and all processes and threads spawned by those applications, are assigned a priority of 13 or less, the real-time process  212  is assigned a higher priority (&gt;13) than any of the processes or threads in the non-real-time process, giving the real-time application higher execution priority. Therefore, the real-time display process  212  processes messages from the OS  202  in a rate determinate manner. One skilled in the art will understand that this guarantees that all messages sent to the real-time display process  212  will be processed properly because the real-time process has a higher priority and will not be interrupted by non-real-time threads.  
         [0023]    In addition, the ‘application boost’ parameter for the non-real-time processes and threads is set to “None”. The real-time network  114  must use LAN switches instead of hubs. Routers are not allowed in the network  114 . The computing environment is further controlled to minimize the invocation of Interrupt Service Routines and Deferred Procedure Calls. The working set (page frames used to contain memory pages in a virtual memory environment) for the real-time process  212  is locked down using a device driver in the OS  202  so that the working set is not swapped out to the storage device  104  during virtual memory swaps. Finally, a GDI probe in the OS  202  locks down an instance of the GDI engine and its associated resources for use exclusively by the real-time process  212 .  
         [0024]    The architecture  20  illustrated in FIG. 2, thus, includes two executables, one for handling the non-real-time data and one for handling the real-time data. This architecture provides the following advantages. First, the separation of executables provides robustness. There are two separate message queues maintained by the OS  202 . If one queue becomes blocked, the other will still operate. Second the display device  112  is driven with two separate and independent graphical display interfaces. The common human interface  210  provides only a single window display interface in which different windows are arranged in a parent-child relation, requiring message and/or event propagation from child to parent and back again. By providing a separate graphical interface for the real-time display process, there is no parent-child relationship with other windows, improving reliability and decreasing message and/or event propagation. This, in turn, decreases the latency time from receipt of real-time data from the real-time signal source  110  to display of images representing that data on the display device  112 .  
         [0025]    One skilled in the art will understand that, to improve readability and controllability by the user, it is desirable to make the graphical ‘look’ of the real-time display process  212  the same as, or very similar to, the ‘look’ of the non-real-time display generated under the control of the common human interface  210 . In the illustrated embodiment, the graphical interface generated by the real-time display process  212  is designed to graphically integrate with the graphical interface generated by the common human interface  210 . More specifically, in the illustrated embodiment the graphical interface of both the real-time display process  212  and the common human interface  210  use a tabcard paradigm. The process for generating the combined display will be described in more detail below. One skilled in the art will understand that the particulars of the ‘look’ are not germane to the present invention, only that they are the same or similar for the non-real-time and real-time processing.  
         [0026]    The image generated by the real-time process  212  is combined with the image generated by the non-real-time process  204 ,  206 ,  208 ,  210  by use of the graphics device interface (GDI) engine built into the OS  202 . One skilled in the art will understand that the GDI engine receives image descriptive instructions from applications. In response to these instructions, the GDI updates the values stored in the video memory in the hardware video adapter (not shown) to represent the combined images of the application programs. The video adapter, in turn, generates video signals for the display device  112  in response to the contents of the video memory.  
         [0027]    The real-time process  212  requests and receives an identifying graphics handle from the OS  202  in the usual manner. The single-thread real-time process  212  then receives the real-time signals from the real-time signal source  110  and, identified by the assigned graphics handle, generates instructions for the GDI engine for displaying the desired real-time image. The real-time process  212  then makes a call to the instance of the GDI assigned exclusively to the real-time process  212  to provide these instructions. This GDI engine is assigned the same high priority as the real-time process  212  so that its execution may not be interrupted by the non-real-time applications. The GDI engine, in turn, conditions the display device  112  to display the combined real-time and non-real-time images via the display device driver.  
         [0028]    More specifically, in the illustrated embodiment where the real-time signals are ECG signals, the real-time display process thread receives the ECG electrode signals from the real-time signal source  110  or the real-time LAN  114  and generates a bit map representing the instantaneous waveform images of the 12 ECG lead signals. The real-time process thread  212  then directly calls the GDI in the OS  202  and gives it instructions (bit block transfer instruction) to transfer the bit map to the video memory in the display device  112 . The GDI engine transfers the bit map to the appropriate location in the video memory in the video adapter.  
         [0029]    Using this technique, the real-time image may be integrated with the non-real-time images using the same ‘look’, as provided by the GDI of the OS  202 . One skilled in the art will understand that is may also be possible to interface directly with the display device adapter, although this presents many security and reliability problems. One skilled in the art will further understand that other interface methods, such as DirectX may also be used to provide the image representative signals to the video adapter.  
         [0030]    [0030]FIG. 3 is a screen diagram illustrating real-time images displayed by the system according to the present invention under the control of the real-time display process  212 . FIG. 3 illustrates an exemplary 12 lead ECG image. In FIG. 3, the display device  112  includes a display screen  113 , such as the face of a CRT, which displays respective images  302  of 12 real-time waveforms (I, II, III, aVR, aVL, aVF, V 1 , V 2 , V 3 , V 4 , V 5  and V 6 ). These waveforms are updated in real-time within the latency limit (200 ms) described above. The waveforms are displayed as if they were contained in a tabbed page  304  having an associated tab  306  which includes indicia (“Patient View”) identifying the contents of that associated page. An additional tab  312  will be described in detail below.  
         [0031]    [0031]FIG. 4 illustrates a display screen  113  in which a non-real-time display image  308  of a chest X ray is displayed in a tabbed page  310 . The tabbed page  310  includes an associated tab  312  which includes indicia (“Custom View”) identifying the contents of the associated page. This tabbed page  310  overlays the real-time data tabbed page associated with the tab  306 , completely obscuring it. One skilled in the art will understand that the image illustrated in FIG. 4 represents only a single tabbed page, but that more than one such tabbed page may be simultaneously made available, each representing different non-real-time data. Furthermore, each tabbed page may simultaneously display more than one window, each displaying an image representing respective non-real-time data. For example, as described above, textual lab results or web pages may be simultaneously displayed on different tabbed pages or in overlapping windows on a single tabbed page, in a manner controlled by the Windows NT operating system.  
         [0032]    As described above, and as is well known to one skilled in the art, it is possible for the non-real-time processing software to malfunction. Should this happen, it is possible for the real-time (ECG) information to be blocked from sight by the image of the non-real-time information displayed on the display device  212 . For example, should the non-real-time portion ( 204 ,  206 ,  208 ,  210 ) of the program architecture  20  malfunction while displaying the image illustrated in FIG. 4, the images representing the real-time ECG data  302  will be hidden. To provide a solution to this problem, the OS  202  is conditioned to be responsive to data from the user input signal source  108  to activate the tabbed page  304  displaying images  302  representing the real-time information from the real-time signal source  110 , as in FIG. 3. For example, a specific key or key combination, e.g. &lt;Control-R&gt;, on a keyboard is specially recognized by the OS  202 , and when recognized, the real-time display  302 , being generated by the real-time display process  212 , is displayed, atop the frozen non-real-time image  308 . The key or key combination is termed a ‘hot key’, and the functions necessary to implement this are part of the Windows NT operating system.  
         [0033]    In another situation, the images representing the real-time information may be partially obscured by an image representing non-real-time information. FIG. 5 is a screen diagram illustrating the real-time images  302  atop which a window  314  including textual lab results is displayed. The window  314 , generated by the non-real-time portion ( 204 ,  206 ,  208 ,  210 ) of the software architecture  20 , partially obscures the real-time images  302 . That portion of the real-time images  302  which remains visible continues to display the real-time data received from the real-time signal source  110 . However, the real-time portion behind the window  314  is not visible. Should the non-real-time portion ( 204 ,  206 ,  208 ,  210 ) of the program architecture  20  malfunction while displaying the image illustrated in FIG. 5, the portion of the images representing the real-time ECG data  302  obscured by the window  314  will be hidden. In this case, the OS  202  recognizes signals from the user input signal source  108  representing a mouse click in the area of the display screen  113  outside of the window  314  and activates the real-time images  302 , making them completely visible. Alternatively, the hot key combination, described above, may also be used to activate the real-time images  302 , making them visible.  
         [0034]    The inventor has also realized that it is possible to monitor the operation of the non-real-time portion ( 204 ,  206 ,  208 ,  210 ) of the software ( 20 ) to identify indications that the non-real-time portion has malfunctioned or is in danger of malfunctioning. In response to such indications, it is possible to control the non-real-time portion in such a manner that the malfunction is automatically corrected or avoided.  
         [0035]    One skilled in the art will understand that the non-real-time processes should not be allowed to interfere with the operation of the real-time process. As described above, the OS  202  maintains information concerning the operation of the application programs, the operating system and the computer system in general. However, during standard operations, the operating system does not monitor this information or perform any functions based on the values of this information.  
         [0036]    The architecture  20  illustrated in FIG. 2 further includes a software and hardware monitor  214 . The monitor  214  monitors the information (described above) which is maintained in the OS  202 . The monitor  214  then performs actions based on the values of the information in the OS  202 . The monitor process  214  is made very simple to ensure maximum reliability and is assigned the highest or a very high priority to ensure that it is always able to execute.  
         [0037]    In general, the OS  202  maintains an indication of the usage of various resources. The monitor process  214  retrieves the usage values from the OS  202  and monitors the amount of resources available. If the amount decreases to a dangerously low level, corrective actions are taken. For example, in an appropriate case, non-real-time processes are terminated to free resources taken by those processes for use by the real-time process. That is, if one of the non-real-time processes malfunctions, then that process is terminated. The terminated process may then be automatically restarted. Alternatively, notifications may be sent as an alert to a user that a problem exists. In response to such an alert, the user can take corrective actions.  
         [0038]    More specifically, there are several groups of resources monitored by the process monitor  214 : the availability of general resources; the availability of system resources; the availability of computer resources; and the operation of the non-real-time processes, tasks and threads. The following four tables describe respective resource groups monitored by the monitor process  214 . Within each table, a first column sets out the resource monitored. The second column sets out an explanation of the check, e.g. why it is important, what effect it might have, and how it is monitored, etc. The third column sets out the parameters which indicate a failure for that resource. Unless indicated otherwise, these parameters are variable and any threshold value may be changed by the user at any time. One skilled in the art will further understand that even those parameters indicated by a specific number are only related to the illustrated embodiment and a range of permissible numbers is available for those parameters. The fourth column sets out the actions which are taken when a failure is indicated. Table 1 illustrates memory resource checks. Table 2 illustrates system resource checks. Table 3 illustrates computer resource checks. Table 4 illustrates process checks.  
                                 TABLE 1                           Memory Resource checks            Specific       Failure           Check   Check Explanation   Parameters   Failure Action               Page Fault   If the Page Fault count   The Page Fault   An attempt will be       count.   is growing, then the   count above a   made to increase           system&#39;s memory is   predetermined   Working Set           too heavily loaded,   threshold   size of the real-                   time process and                   to decrease the                   Working Set                   sizes of all non-                   real-time                   processes.               The real-time   All non-real-time               process&#39;s Page   applications will               Fault count is   be terminated in               still above the   turn, until Page               threshold.   Fault count                   returns to normal                   or there are no                   more non-real-                   time applications.                  
 
         [0039]    [0039]                                 TABLE 2                           System Resource Checks            Specific       Failure           Check   Check Explanation   Parameters   Failure Action               Total   Too high usage will   Over 80%   All non-real-time       Processor   lead to overall system       applications will       Usage   unresponsiveness. If       be terminated in           using a multiprocessor       turn.           computer, System:           Total Processor Time           for the system as a           whole, and Processor:           Processor Time for           each processor may be           monitored separately.       Processor   Sustained presence of   Sustained   All non-real-time       Queue   two or more tasks in   count of 2 or   applications will       Length   the queue indicates   greater lasts   be terminated in           processor congestion   longer than 5   turn.               minutes       Available   The Available Mem-   Available   An attempt will be       Memory   ory counter indicates   memory is   made to force all           how many bytes of   below a   non-real-time           memory are currently   predetermined   processes to be           available for use by   amount.   paged out. If that           processes. Low values       does not help, all           for the Available Bytes       non-real-time           counter can indicate       applications will           that there is an overall       be terminated in           shortage of memory on       turn.           the computer or that an           application is not           releasing memory.       Paging   The Pages/sec counter   Hard disk   An attempt will be       Rate   indicates the number   paging rate is   made to force all           of pages that either   too high.   non-real-time           were retrieved from       processes to be           disk due to hard page       paged out. If that           faults or written to       does not help, all           disk to free space in       non-real-time           the working set due to       applications will           page faults. A high       be terminated in           rate for the Pages/sec       turn.           counter could indicate           excessive paging.           Monitor the Memory:           Page Faults/sec           counter to make sure           that the disk activity is           not caused by paging.                    
         [0040]    [0040]                                 TABLE 3                           Computer Resource Monitor Checks            Specific       Failure           Check   Check Explanation   Parameters   Failure Action               Network   Ping time shows the   Ping time is   A high-priority       status.   rate of data exchange   longer than a   notification is sent           on the network. If a   predetermined   to the system-wide           ping times out, it   interval,   Notification           means that the       component.           connection is broken           or unacceptably slow,       CPU chip   CPU Chip temperature   The   A medium-priority       tempera-   rising too high in-   temperature is   notification is sent       ture.   dicates malfunctioning   above a   to the system-wide           in the CPU cooling   predetermined   Notification           system and may lead   threshold   component.           to processor damage           and malfunction of the           processes.       Input   Voltage outside of the   Voltage is   A medium-priority       voltage   standard range will   outside of   notification is sent       from   lead to the partial or   predetermined   to the system-wide       the power   complete system   limits,   Notification       source.   shutdown. Wild power       component.           fluctuation may be           indicative of power           source&#39;s failure.       Hard disk   Hard disk has a usage   Disk spinning   A single low-       spinning   time limit documented   time exceeds a   priority notification       time.   by the manufacturer.   specified   is sent to the           When the disk spin-   interval,   system-wide           ning time approaches       Notification           the specified limit,       component.           hard disk service or           replacement may be           needed to prevent           failures.       An   Either the windowing   The partition is   A high-priority       important   operating system   over 80% full.   notification is sent       logical   partition, or real-time       to the system-wide       hard   system partition (if it       Notification       disk&#39;s   is not installed on the       component.       partition   operating system       is low on   partition) of hard disk       space   is nearing its capacity.           Some data has to be           removed from the           partition,                    
         [0041]    [0041]                                 TABLE 4                           Process Checks            Specific       Failure           Check   Check Explanation   Parameters   Failure Action               Handle   If the Handle count for   Handle count   The process will       count   a process is increasing,   reaches a   be terminated.           the process is probably   threshold level           leaking handles.   and keeps               steadily               increasing after               that.       Working   If the Working Set size   The Working   An attempt will be       Set size   of a process is   Set size reaches   made to empty           increasing, the process   a threshold   the Working Set.           is probably leaking   level   If the Working           memory or allocating       Set could not be           excessive amounts of       emptied or is still           memory.       above the                   threshold, the                   process will be                   terminated.       Verify   Responsiveness means   The process   The process will       respons-   that the process has   has not retriev-   be terminated.       iveness of   retrieved messages   ed messages       processes   from its message   from its       with GUI   queue recently. If it   message queue           has not, it is probably   within last           hung up.   10 seconds.       CPU load   If a process consistent-   The process   The process will           ly spends large   consistently   be terminated.           percentage of   consumes over           process&#39;s time   90% of           executing processor   process&#39;s time           instructions, it is   to execute           probably running a   processor           busy loop,   instructions.                    
         [0042]    A system operating in the manner described above will be able to display images representing real-time data with a high degree of reliability and minimum latency simultaneously with images representing non-real-time data.

Technology Category: 1