Abstract:
An interconnectivity scheme for a PC Theatre system includes the use of compatible plug and display connectors on both the display and the host computer. Audio/video signals received by either the display or the computer may be processed by the computer and transmitted between these devices in a standardized signal format using the compatible connectors. The control scheme for facilitating master-slave control of the display by the computer includes the use of various standardized signals and formats as well to ensure compatibility between products manufactured by different companies.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This non-provisional application is related to provisional application serial no. 60/054,616, filed on Aug. 4, 1997, the entirety of which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field Of The Invention 
     The present invention relates generally to devices with multiple functional modalities and, in particular, to the interconnectivity of various elements of such devices. 
     2. Description Of The Related Art 
     With the advent of multi-media devices, the integration of information, entertainment, and communications technologies has become a much sought-after goal. A highly visible example of this trend is the attempt to integrate computer technologies, such as personal computers for example, with consumer/home electronics technologies, such as televisions (TV), video games, telephones, and video/laser discs for example. One of the likely products of this convergence may be a single integrated device capable of providing information, entertainment, and communications functions. Such a device may, at least in part, utilize the available communications bandwidth, mass storage, and graphics handling capabilities of the personal computer (PC) in a variety of applications to provide a highly versatile product to consumers. 
     In spite of many recent advances in the area of multi-media, several problems persist. One of the more significant difficulties relates to interconnecting a computer with one or more consumer/home electronic devices. In an integrated device of this kind, the interconnection between these various functional elements of the multi-media device should permit a user to control the modes of “functionalities” in a manner that facilitates a seamless transition from one functionality to another. While such controlled interconnectivity may be relatively simple to realize in a multi-media device designed and manufactured by a single manufacturer, it would undoubtedly become an exceedingly complex, if not impossible, task to provide such interconnectivity among different functional elements provided by different manufacturers. 
     Of the new generation of multi-media products, the one of most interest will likely be the convergence of the TV and PC to create a new category of entertainment products. These products will give the consumer more entertainment options by combining the features of a PC and TV in a truly converged environment that is as easy to use as a standard TV. The computing power of a properly adapted computer, called a PC Theatre system, coupled with a large-screen display make this an excellent living room platform for digital and interactive services that are available now, and new services that will be available in the future. 
     As this new product category grows, consumer electronics (CE) companies are likely to include monitor functionality in their TVs. At the same time, PC manufacturers are likely to add TV functionality to their computers. This increased functionality in both the TV and PC greatly increases the value to the consumer. 
     However, as alluded to above, since there are no standards for this new product category, products from different manufacturers will be incompatible. Standard interconnectivity should facilitate consumer confidence in this new product, as well as growth of this new product category. Such standard interconnectivity will allow companies from both industries to develop compatible PC Theatre products so that the consumer will be able to select a display and a PC from different manufacturers and use them together as a system without the need for custom cables and complicated setup procedures. In addition, the PC Theatre standards should be compatible with existing standards so PC Theatre displays and computers may be used with standard products. 
     The present invention may address one or more of the problems discussed above. 
     SUMMARY OF THE INVENTION 
     Certain aspects commensurate in scope with the originally claimed invention are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below. 
     In accordance with one aspect of the present invention, there is provided an interconnection between a display and a computer. The interconnection includes an audio/video input adapted to receive audio signals and video signals. An audio/video signal processor is coupled to the audio/video input for processing the audio signals and the video signals. An analog/digital plug and display connector is coupled to the audio/video signal processor and is adapted to be coupled to the display. The analog/digital plug and display connector is adapted to transmit the audio signals and the video signals to the display. A universal serial bus hub is coupled to the analog/digital plug and display connector. A universal serial bus port is coupled to the universal serial bus hub. 
     In accordance with another aspect of the present invention, there is provided an interconnection between a display and a computer. The inter connection includes an audio/video input adapted to receive audio signals and video signals. An audio/video signal processor is coupled to the audio/video input for processing the audio signals and the video signals. An analog or digital plug and display connector is coupled to the audio/video signal processor and is adapted to be coupled to the computer. The analog or digital plug and display connector is adapted to transmit the audio signals and the video signals to the computer. A universal serial bus hub is coupled to the analog or digital plug and display connector. A universal serial bus port is coupled to the universal serial bus hub. 
     In accordance with still another aspect of the present invention, there is provided a PC Theatre system that includes a video display having a first plug and display connector coupled thereto. A computer has a second plug and display connector coupled thereto. The first plug and display connector is connectable to the second plug and display connector. At least one of the video display and the computer includes an audio/video input adapted to receive audio signals and video signals. At least one of the video display and the computer includes an audio/video signal processor coupled to the audio/video input for processing the audio signals and the video signals. The audio signals and the video signals are transmitted between the video display and the computer via the respective plug and display connectors. 
     In accordance with yet another aspect of the present invention, there is provided, in a PC Theatre system that includes a video display and a computer, where at least one of the video display and the computer includes an audio/video input adapted to receive audio signals and video signals, and where at least one of the video display and the computer includes an audio/video signal processor coupled to the audio/video input for processing the audio signals and the video signals, an improvement that includes a first plug and display connector coupled to the video display and a second plug and display connector coupled to the computer. The first plug and display connector is connectable to the second plug and display connector to transmit the audio signals and the video signals between the video display and the computer. 
     In accordance with a further aspect of the present invention, there is provided an interconnection between a display and a computer. The interconnection includes an audio/video input device adapted to receive audio signals and video signals from the computer. An audio/video signal processor is coupled to the audio/video input device for processing the audio signals and the video signals. An enhanced video connector is coupled to the audio/video signal processor and is adapted to be coupled to the display. The enhanced video connector is adapted to transmit the audio signals and the video signals to the display. A universal serial bus hub is coupled to the enhanced video connector. A universal serial bus port is coupled to the universal serial bus hub. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: 
     FIG. 1 illustrates a high level block diagram of an exemplary PC Theatre system; 
     FIG. 2 illustrates an analog/digital (A/D) Plug and Display (P&amp;D) connector; 
     FIG. 3 illustrates an analog P&amp;D connector; 
     FIG. 4 illustrates a digital P&amp;D connector; 
     FIG. 5 illustrates a diagrammatic view of interaction between the connectors of FIGS. 2,  3 , and  4 ; 
     FIG. 6 illustrates PC Theatre signal interfaces between a PC and a display; and 
     FIG. 7 illustrates a flowchart depicting a process for configuring an interface between a PC and a display; 
     FIG. 8 illustrates a detailed block diagram of one embodiment of a PC Theatre system; and 
     FIG. 9 illustrates a detailed block diagram of another embodiment of a PC Theatre system. 
    
    
     DOCUMENTS REFERRED TO IN THE SPECIFICATION 
     This specification refers to the following documents: 
     VESA Display Data Channel (DDC) Standard, Version 3.0, Sep. 15, 1997; 
     VESA Extended Display Identification (EDID) Standard, Version 3.0, Nov. 13, 1997; 
     VESA Monitor Control Command Set (MCCS) Standard, V 1.0; 
     VESA Display Power Management Signaling (DPMS) Standard Version 1.1, Aug. 20, 1993; 
     VESA Plug and Display (P&amp;D) Standard, Version 1.0, Jun. 11, 1997; 
     VESA Display Monitor Timing Specifications (DMTS), Version 1.7, Dec. 18, 1996; 
     Universal Serial Bus Specification, Version 1.0, Jan. 15, 1996; 
     USB Class Definition for Human Interface Devices (HID) Specification, Version 1.0, Dec. 12, 1996; 
     Universal Serial Bus (USB) Monitor Control Class Specification, Version 1.0, Jan. 5, 1998; 
     Universal Serial Bus Device Class Definition for Audio Devices, Version 1.0, Mar. 18, 1998; 
     Universal Serial Bus Device Class Definition for Audio Data Formats, Version 1.0, Mar. 18, 1998; 
     Universal Serial Bus HID Usage Tables, Version 1.0, Oct. 30, 1997; and 
     IEEE Standard for a High Performance Serial Bus, 1394-1995. 
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     Before discussing the drawings specifically, it should be recognized that as the PC and TV converge, a new product category will be created. The VESA PC Theatre Interconnectivity architecture described herein allows both Personal Computer and Consumer Electronics companies to develop products that are compatible, self configuring, work together as a single system, and are easy to use. The primary focus of this specification is the interface between the PC (and simple computing device such as a set-top box) and the large-screen display. 
     This specification discusses a PC Theatre Interconnectivity (PCTI) architecture that allows PC and CE manufacturers to produce PC Theatre computer and display products that are compatible and support automatic configuration. The PCTI architecture has been created using existing VESA and USB standards as building blocks to support identification of the display by the PC, bi-directional communication, display control by the PC, sharing of the display&#39;s resources by the PC, and transportation of audio and video between the display and PC. 
     When the display is in stand-alone mode, product features such as channel mapping and government mandated features such as Closed Caption Decoding and V-Chip will be implemented and controlled by the display&#39;s internal controller. When the display is in slave-mode and the PC has complete control of the tuner and stores the channel map, the host computing device and application software will be responsible for the channel mapping, Closed Caption Decoding, and V-Chip requirements. 
     PC Theatre is a consumer entertainment system that merges computing and traditional forms of media and entertainment content. This system combines the features of a TV and a multimedia PC, delivering more entertainment options in a truly converged environment. The consumer may watch TV, use the PC, or do both at the same time. 
     Turning now to the drawings, and referring initially to FIG. 1, a PC Theatre system is illustrated and generally designated by the reference numeral  10 . The system  10  includes two main parts—a display  12  and a computing device, such as a personal computer (PC)  14 . The system  10  also includes one or more video sources  16  and  18 . As illustrated, one set of video sources  16  may be coupled to the PC  14 , and another set of video sources  18  may be coupled directly to the display  12 . The PCTI standard is primarily concerned with the interface between the PC  14  and display  12 . 
     The display  12  may have the same functionality as a standard VGA monitor with enhancements for displaying TV video. Optionally, the display  12  may also have all the functionality of a stand-alone TV, including the capability to display standard interlaced TV video. A remote control  20  may be included in the system  10  for delivering control signals to an infrared sensor (not shown) on the display  12 . 
     The PC  14  may be a typical multimedia system with USB support and a video subsystem capable of combining PC and TV video from the video sources  16 . The PC  14  may also include IEEE 1394-1995 functionality. In addition, a remote control  22  may be included in the system  10  for delivering the control signals to an radio frequency sensor (not shown) or to an infrared sensor (not shown) on the PC  14 . Also, the system  10  may include a keyboard  24 , that may be coupled to the PC  14  via a standard cable connection or via a standard RF link. 
     The interconnectivity between the PC Theatre system PC  14  and the display  12  will now be described in greater detail. This interconnectivity is defined using existing VESA and USB standards as building blocks to support identification of the display  12  by the PC  14 , bi-directional communication, display control by the PC, sharing of the display&#39;s resources by the PC  14 , and transport of audio and video between the display  12  and PC  14 . 
     The key points of the PC Theatre interface are as follows: 
     The PC  14  and display  12  are connected using VESA Plug and Display (P&amp;D) Standard V1.0 connectors, as illustrated in FIGS. 2-4. 
     The PC  14  drives the display  12  with a standard RGB or TMDS video signal. 
     The PC  14  and display  12  support two different viewing modes: one configured for the display of PC graphics, and the other configured for the display of TV video. 
     The PC  14  and display  12  support at least 480 active lines per frame of progressively scanned video. 
     The PC  14  and display  12  support VESA Display Data Channel (DDC) V3.0 and Extended Display Identification Data (EDID) V3.0 Standards for identification of the display&#39;s capabilities. 
     The PC  14  and display  12  support VESA Display Power Management Signaling (DPMS) Standard V1.1 for PC control of the display&#39;s power state. 
     The PC  14  and display  12  support the USB Monitor Control Class Specification V1.0 and VESA Monitor Control Command Set (MCCS) Standard (proposal) for software control of the display by the PC. 
     The display  12  and PC  14  use separate analog audio cables to transport stereo audio from the PC  14  to the display  12  and optionally from the display  12  to the PC  14 . The PC  14  also supports the USB Device Class Definition for Audio Devices specification V1.0 and USB Device Class Definition for Audio Data Formats specification V1.0 for the support of USB audio. 
     All user input (remote, keyboard, gamepads, display front button panel) is passed from the display  12  to the PC  14  for processing (when the display is in a slave mode) over USB according to the USB Class Definition for Human Interface Devices (HID) specification V1.0, and the USB HID Usage Tables specification V1.0. The display  12  may also support a stand-alone mode where user input is processed internally. 
     The VESA P&amp;D Standard V1.0 combines many signals into one connector with support for digital displays (TMDS), analog displays (RGB), IEEE-1394, USB, and DDC. The main advantages of this connector are virtually any type of display can be supported and all required signals for PC Theatre can be supported. Thus, only one cable is used between the PC  14  and display  12 . It should also be noted that other connectors, such as those supporting the VESA Enhanced Video Connector Standard, may also be used. In fact, the EVC connector has been redesignated as a P&amp;D-A connector. 
     The P&amp;D connector supports the following signals: 
     Standard analog video signals (RGB, H &amp; V sync) for support of analog displays. 
     Transmission Minimized Digital Signaling (TMDS) video for support of digital displays. 
     IEEE 1394-1995 pair for support of digital video and audio paths to and from the display. 
     USB, 12 Mb/s for support of PC control of the display, sending user input from the display to the PC, and audio paths to and from the display. 
     DDC2B for identification of the display&#39;s capabilities. 
     The PC Theatre PC  14  supports the P&amp;D-A/D (analog/digital) connector  30  illustrated in FIG.  2 . The display  12  supports either the P&amp;D-A (analog) connector  32 , illustrated in FIG. 3, or the P&amp;D-D (digital) connector  34 , illustrated in FIG.  4 . The P&amp;D-A/D connector  30  is capable of receiving and transmitting both analog and digital signals, depending upon the type of monitor being used as the display  12 . The P&amp;D-A connector  32  is used on analog monitors, and the P&amp;D-D connector  34  is used on digital monitors. It should be noted that the connector  32  shown in FIG. 3 is the P&amp;D-A receptacle and not the plug that is used for the monitor cable. Similarly, it should be noted that the connector  34  shown in FIG. 4 is the P&amp;D-D receptacle and not the plug that is used for the monitor cable. Furthermore, although PC Theatre products should support this P&amp;D standard, if the display  12  or the PC  14  does not use a P&amp;D connector, an adapter cable may be included that combines the supported signals into a P&amp;D connector. 
     As mentioned above, the P&amp;D-A/D connector  30  on the PC  14  supports both the P&amp;D-A connector  32  and P&amp;D-D connector  34 . FIG. 5 explains the interaction between the different connectors in the P&amp;D family, where the blacked-out contacts illustrate the active signal paths in the respective connectors. It should be noted that the connectors  32  and  34  illustrated in FIG. 5 are shown as the plug versions of the respective connector, while the connector  30  is shown as the receptacle version of the connector. As can be clearly seen, either the analog connector  32  or the digital connector  34  may be plugged into the connector  30 . 
     Now that the basic elements of the system  10  have been described, along with the preferred connectors that couple these elements together, attention may now be drawn to the interconnectivity signals used to provide PC Theatre functionality. The PC Theatre PC  14  supports the signal interfaces and connectors listed below in Table 1. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 PC Signal Interfaces and Connectors 
               
             
          
           
               
                 SIGNAL 
                 CONNECTOR 
                 SIGNAL USE 
               
               
                   
               
               
                 RGB (H&amp;V sync) 
                 P&amp;D 
                 Analog video to drive display 
               
               
                 TMDS 
                 P&amp;D 
                 Digital video to drive display 
               
               
                 USB 
                 P&amp;D 
                 Control of display, return of user 
               
               
                   
                   
                 input, and support of USB audio 
               
               
                 DDC 
                 P&amp;D 
                 For EDID support to identify 
               
               
                   
                   
                 display 
               
               
                 Stereo Analog 
                 Stereo 3.5 mm jack 
                 Stereo analog audio output for 
               
               
                 Audio Output 
                   
                 amplifier in display 
               
               
                 Stereo Analog 
                 Stereo 3.5 mm jack 
                 Stereo analog audio input for 
               
               
                 Audio Input 
                   
                 support of tuner or connector 
               
               
                   
                   
                 panel in display 
               
               
                 Composite Input 
                 Composite video 
                 Composite video source input. 
               
               
                   
                 connector (yellow) 
                 A S-video connector may be 
               
               
                   
                   
                 substituted if an adapter for 
               
               
                   
                   
                 Composite video support is 
               
               
                   
                   
                 supplied with the product. 
               
               
                   
               
               
                 NOTE: If the P&amp;D connector is not supported, a P&amp;D adapter may be supplied with the product.  
               
             
          
         
       
     
     The PC Theatre display  12  supports the signal interfaces and connectors listed below in Table 2. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Display Signal Interfaces and Connectors 
               
             
          
           
               
                 SIGNAL 
                 CONNECTOR 
                 SIGNAL USE 
               
               
                   
               
               
                 RGB (H&amp;V sync) 
                 P&amp;D 
                 Analog or digital video to 
               
               
                 or TMDS 
                   
                 drive display 
               
               
                 USB 
                 P&amp;D 
                 Control of display, return of user 
               
               
                   
                   
                 input, and optional audio support 
               
               
                 DDC 
                 P&amp;D 
                 For EDID support to identify 
               
               
                   
                   
                 display 
               
               
                 Stereo Analog 
                 Two RCA jacks 
                 Stereo analog audio input 
               
               
                 Audio Input 
               
               
                   
               
             
          
         
       
     
     The diagram in FIG. 6 shows the PC Theatre communication interface  35  between the PC  14  and display  12 , as well as inputs which may be received by the display  12  and the PC  14 . The display  12  and the PC  14  may receive baseband or modulated audio/video (A/V) inputs at  36  and  38 , respectively, from sources  16  or  18 , for instance. The display  12  and the PC  14  may also receive input signals from an additional input device  40 , which may include one or more devices, such as a keyboard, mouse, remote control, joystick, etc. In regard to the signal interfaces, the user input and command signals are transmitted on USB lines  42  and  44 , the digital graphic display signals are transmitted on a TDMS line  46 , the analog graphic display signals are transmitted on an RGB line  48 , the display identification signals are transmitted on a line  50 , the baseband video input signals are transmitted on a line  52 , and the audio output and input signals are transmitted on lines  54  and  56 , respectively. 
     The individual P&amp;D signals in the following Tables are used for PC Theatre functionality. The signals for the PC  14  support both digital and analog displays. The signals for the display  12  are different depending on the type of display. 
     The PC  14  supports the individual signals listed in Table 3 for the P&amp;D-A/D connector  30 . 
     
       
         
               
             
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 System PC P&amp;D-A/D Connector Signals 
               
             
          
           
               
                 PIN 
                 SIGNAL 
               
               
                   
               
               
                  1 
                 TMDS Data2 + 
               
               
                  2 
                 TMDS Data2 − 
               
               
                  3 
                 TMDS Data2 Return 
               
               
                  4 
                 Sync return 
               
               
                  5 
                 Horizontal sync (TTL) 
               
               
                  6 
                 Vertical sync (TTL) 
               
               
                  7 
                 TMDS Clock Return 
               
               
                  8 
                 Hot Plug Detection (+5 VDC input) 
               
               
                 11 
                 TMDS Data1 + 
               
               
                 12 
                 TMDS Data1 − 
               
               
                 13 
                 TMDS Data1 Return 
               
               
                 14 
                 TMDS Clock + 
               
               
                 15 
                 TMDS Clock − 
               
               
                 16 
                 USB data + 
               
               
                 17 
                 USB data − 
               
               
                 18 
                 USB/1394 common mode shield 
               
               
                 21 
                 TMDS Data0 + 
               
               
                 22 
                 TMDS Data0 − 
               
               
                 23 
                 TMDS Data0 Return 
               
               
                 25 
                 DDC return 
               
               
                 26 
                 DDC data (SDA) 
               
               
                 27 
                 DDC clock (SCL) 
               
               
                 28 
                 +5 VDC (output) 
               
               
                 C1 
                 Red Video 
               
               
                 C2 
                 Green Video 
               
               
                 C4 
                 Blue Video 
               
               
                 C5 
                 Video Return 
               
               
                   
               
             
          
         
       
     
     An analog display  12  supports the individual signals listed in Table 4 for the P&amp;D-A connector  32 . It should be noted that the analog audio and S-video paths specified in the original EVC specification are not supported with the P&amp;D-A version of the connector. 
     
       
         
               
             
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Analog Display P&amp;D-A Signals 
               
             
          
           
               
                 PIN 
                 SIGNAL 
               
               
                   
               
               
                  4 
                 Sync return 
               
               
                  5 
                 Horizontal sync (TTL) 
               
               
                  6 
                 Vertical sync (TTL) 
               
               
                  8 
                 Hot Plug Detection (+5 VDC output to display) 
               
               
                 16 
                 USB data + 
               
               
                 17 
                 USB data − 
               
               
                 18 
                 USB/1394 common mode shield 
               
               
                 25 
                 DDC return 
               
               
                 26 
                 DDC data (SDA) 
               
               
                 27 
                 DDC clock (SCL) 
               
               
                 28 
                 +5 V DC (input to display) 
               
               
                 C1 
                 Red Video 
               
               
                 C2 
                 Green Video 
               
               
                 C4 
                 Blue Video 
               
               
                 C5 
                 Video Return 
               
               
                   
               
             
          
         
       
     
     The digital display  12  supports the individual signals listed in Table 5 for the P&amp;D-D connector  34 . 
     
       
         
               
             
               
               
             
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Digital Display P&amp;D-D Connector Signals 
               
             
          
           
               
                 PIN 
                 SIGNAL 
               
               
                   
               
             
          
           
               
                 1 
                 TMDS Data2 + 
               
               
                 2 
                 TMDS Data2 − 
               
               
                 3 
                 TMDS Data Return 
               
               
                 7 
                 TMDS Clock Return 
               
               
                 8 
                 Hot Plug Detection (+5 VDC output to PC) 
               
               
                 11 
                 TMDS Data1 + 
               
               
                 12 
                 TMDS Data1 − 
               
               
                 13 
                 TMDS Data1 Return 
               
               
                 14 
                 TMDS Clock + 
               
               
                 15 
                 TMDS Clock − 
               
               
                 16 
                 USB data + 
               
               
                 17 
                 USB data − 
               
               
                 18 
                 USB/1394 common mode shield 
               
               
                 21 
                 TMDS Data0 + 
               
               
                 22 
                 TMDS Data0 − 
               
               
                 23 
                 TMDS Data0 Return 
               
               
                 25 
                 DDC return 
               
               
                 26 
                 DDC data (SDA) 
               
               
                 27 
                 DDC clock (SCL) 
               
               
                 28 
                 +5 V DC (input to display) 
               
               
                   
               
             
          
         
       
     
     The display  12  and the PC  14  may also support the signals in Table 6. These signals are recommended to support IEEE 1394-1995 for the transportation of digital audio and video. 
     
       
         
               
             
               
               
             
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Additional Signals for PC and Display 
               
             
          
           
               
                 PIN 
                 SIGNAL 
               
               
                   
               
             
          
           
               
                 9 
                 1394 TPA* 
               
               
                 10 
                 1394 TPA 
               
               
                 19 
                 1394 Vg 
               
               
                 20 
                 1394 Vp 
               
               
                 29 
                 1394 TPB 
               
               
                 30 
                 1394 TPB* 
               
               
                   
               
             
          
         
       
     
     In addition to the signal support for the P&amp;D connectors, the PC  14  also provides support for separate analog audio and video connectors. The following specifications may apply for analog audio support: 
     1. Source impedance—1K ohm maximum. 
     2. Load impedance—10K ohm minimum. 
     3. Amplitude—2V RMS maximum, 0.5V RMS nominal. 
     The PC  14  may also support a line-level stereo analog audio output on a 3.5 mm stereo jack using standard pin assignments. This audio output connector is used to support a separate analog audio cable to drive the audio amplifier in the display  12 . In addition, the PC  14  may also support a line-level stereo audio input on a second 3.5 mm stereo jack using standard pin assignments. This audio input connector is used to support a separate audio cable for input of audio. The PC  14  may further support a Composite video connector for Composite video input. A S-video connector may be substituted for the Composite connector if an adapter is provided for a Composite video support. 
     The display  12  supports a line-level stereo analog audio input on two RCA jacks. In addition, if video output to the PC  14  is supported, the display  12  may also support two RCA jacks for audio output and a composite video connector for video output. 
     Referring again to the communication interface  35  illustrated in FIG. 6, this interface is used by the PC  14  to identify and control the display  12 . As mentioned previously, the interface  35  is implemented using DDC-2B and USB communication links. The VESA DDC-2B standard is a simple interface that is based on the I 2 C bus. This interface allows the PC  14  to read and write to the display&#39;s memory space. In this embodiment, the PC  14  is always the master, and the display  12  is always the slave. Only the PC  14  may initiate a communication transaction. 
     The interface  35  is used during the boot-up process to allow the PC  14  to query the display  12  for information on its functionality. This information is then used to configure the operating system and video system. DDC2B support is used in both the PC  14  and display  12 . The DDC2B section of the VESA DDC Standard V3.0 may be referred to for more information. 
     The Universal Serial Bus (USB) is a bidirectional serial bus that operates at speeds of 1.5 and 12 Mb/s. The bidirectional functionality of this bus enables both the PC  14  and the display  12  to initiate a communication transaction. This functionality allows the display  12  to inform the PC  14  about events such as a button press on the display&#39;s front panel. The PC  14  and display  12  support the USB Monitor Control Class Specification V1.0 and VESA Monitor Control Command Set (MCCS) Standard V1.0 for software control of the display by the PC  14 . The PC  14  and the display  12  also support the USB Class Definition for Human Interface Devices (HID) specification V1.0, as well as the USB HID Usage Tables specification V1.0 for transportation of user input from the display  12  back to the PC  14 . In addition, the PC  14  supports the USB Device Class Definition for Audio Devices specification V1.0 and USB Device Class Definition for Audio Data Formats specification V1.0 for the support of USB to transport audio. 
     The PC Theatre system may also support IEEE 1394-1995, which is a high-speed bi-directional serial bus that is capable of speeds greater than 1 Gb/s. This bus is intended to be used to transport video and may also be used to control the display or transport audio. The IEEE 1394-1995 specification may be referred to for more information. Hereafter in this document, IEEE 1394-1995 is referred to as IEEE-1394 or just 1394. 
     The PC  14  controls the display  12  using USB according to the requirements of the USB Monitor Control Class specification V1.0 and VESA Monitor Control Command Set (MCCS) Standard V1.0. In addition to USB, display control may be supported over DDC2B and 1394. Assuming that the PC  14  supports DDC-2B, USB, and 1394 display communication, the recommended method of establishing communication with the display is to first attempt to communicate with the 1394 interface. If this fails, the PC  14  should then attempt to establish communication with the USB interface. If this fails, the PC  14  should then attempt to establish communication with the DDC-2B interface. If this fails, the PC  14  should assume the display  12  does not support software control and disable the software user control interface. 
     If communication between the PC  14  and the display  12  is established, the PC  14  requests the supported controls of the display  12  and configures the user interface accordingly. This communication process is described in the block diagram shown in FIG.  7 . The PC  14  reads the EDID file stored in the display  12  over the DDC interface. (Block  60 ). The PC  14  then requests the status of the display  12  over the 1394 interface. (Block  62 ). If a valid response is received (block  64 ), the PC  14  requests supported controls from the display  14  and configures the display control user interface. (Blocks  66  and  67 ). If not, the PC  14  requests the status of the display  12  over the USB interface. (Block  68 ). If a valid response is received (block  70 ), the PC  14  again requests supported controls from the display  14  and configures the display control user interface. (Blocks  66  and  67 ). If not, the PC  14  requests the status of the display  12  over the DC-2B interface. (Block  72 ). If a valid response is received (block  74 ), the PC  14  again requests supported controls from the display  14  and configures the display control user interface. (Blocks  66  and  67 ). If not, the PC  14  disables the display&#39;s control user interface. (Block  76 ). 
     For identification of the display  12 , support of the VESA Extended Display Identification Data (EDID) Standard V3.0 is utilized to communicate the display&#39;s capabilities to the PC  14 . This information is stored in the display  12  as a condensed memory block. 
     With this information, the operating system and PC video subsystem can configure themselves for use with the display  12 . The support of EDID structure Version 1.1 is advantageously utilized for all PC Theatre products. In addition, EDID Structure version 2.0 is advantageously used for the system unit and digital displays. Version 2.0 of EDID resides at a different memory address in the display  12  to allow both EDID Versions 1.1 and 2.0 to be supported together. Note that if EDID structure Version 2.0 is supported, Version 1.1 support is still used. EDID structure Version 2.0 contains additional information that is used by displays that have additional functionality such as a digital video interface and support of USB. Note the EDID structure version and the version of the EDID standard are not the same. The EDID Standard Version 3.0 may be referred to for information about EDID structures 1.1 and 2.0. 
     The PC  14  also queries the display  12  for the supported controls over USB according to the USB Monitor Control Class Definition specification V1.0 and VESA Monitor Control Command Set (MCCS) Standard V1.0 requirements. For each supported control, the display  12  is capable of reporting the type (continuous or discrete), the maximum value (the minimum value is assumed to be zero), and the current value. This information is used by the PC  14  to configure the user control interface. This user control interface presents a graphical user interface (GUI) of the supported controls. Only the appropriate user controls that are supported by the display are presented to the user. 
     The display manufacturer has the option of reporting the support of controls to the PC  14 . If the display manufacturer wants to process the user input and generate the OSD internally for a specific control when the display  12  is in slave mode, the display  12  simply does not report the support of the control to the PC  14 . For this unreported control, the display  12  intercepts the user commands for this control, processes the commands internally, and generates the OSD internally. 
     The VESA Monitor Control Command Set NCCS) Standard V1.0 gives a complete list of display controls. This specification is written to be protocol-independent and is used as the basis for the USB Monitor Control Class Definition and the VESA DDC Command Interface (DDC/CI) specifications. 
     The display controls in Table 7 are utilized for PC Theatre operation with flat panel displays. It should be noted that some of these controls do not apply to all display technologies. If the display technology does not support, or has great difficulty supporting, a specific control, this control can be considered optional. The Brightness and Contrast controls are used to adjust the display for viewing computer graphics in PC mode and full screen video in TV mode. The Volume and Balance controls are used to provide the minimum control of the audio amplifier in the display. It should be noted that the audio controls are not listed in the USB Monitor Control Class Definition specification and VESA Monitor Control Command Set (MCCS) Standard V1.0. Rather, these controls are listed in the USB Audio Class Definition for Audio Devices specification. 
     
       
         
               
             
               
               
             
           
               
                 TABLE 7 
               
             
             
               
                   
               
               
                 Flat Panel Display Controls for PC Theatre 
               
             
          
           
               
                 COMMAND 
                 DESCRIPTION/VALUE 
               
               
                   
               
               
                 Brightness 
                 Continuous control. Increasing this value increases the 
               
               
                   
                 brightness level of the display. 
               
               
                   
                 Unipolar setting: 00h=min 
               
               
                 Contrast 
                 Continuous control. Increasing this value increases the 
               
               
                   
                 contrast level of the display. 
               
               
                   
                 Unipolar setting: 00h=min 
               
               
                 Volume 
                 Continuous control. Increasing this value causes the 
               
               
                   
                 volume in the left and right audio channels to increase. 
               
               
                   
                 Unipolar setting: 00h=mute 
               
               
                 Balance 
                 Continuous control. Increasing this value maximizes the 
               
               
                   
                 volume in the right audio channel and the volume in the 
               
               
                   
                 left audio channel is decreased. 
               
               
                   
                 Bipolar setting: 00h=max left channel, min right channel 
               
               
                   
               
             
          
         
       
     
     The display controls in Table 8 are utilized for PC Theatre operation with CRT displays. The Brightness and Contrast controls are used to adjust the display for viewing computer graphics in PC mode and full screen video in TV mode. The geometry controls are used to provide the minimum amount of raster position and size adjustment for a high quality display. The overscan control is used to adjust the display so the edges are not visible in fill screen TV mode. This is used to hide noise commonly found on the edge of the picture. The Volume and Balance controls are used to provide the minimum control of the audio amplifier in the display. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 8 
               
             
             
               
                   
               
               
                 CRT Display Controls for PC Theatre 
               
             
          
           
               
                   
                 COMMAND 
                 DESCRIPTION/VALUE 
               
               
                   
                   
               
               
                   
                 Brightness 
                 Continuous control. Increasing this value 
               
               
                   
                   
                 increases the brightness level of the display. 
               
               
                   
                   
                 Unipolar setting: 00h=min 
               
               
                   
                 Contrast 
                 Continuous control. Increasing this value 
               
               
                   
                   
                 increases the contrast level of the display. 
               
               
                   
                   
                 Unipolar setting: 00h=min 
               
               
                   
                 Vertical 
                 Continuous control. Increasing this value 
               
               
                   
                 Position 
                 moves the image toward the top of the display. 
               
               
                   
                   
                 Bipolar setting: 00h=max down 
               
               
                   
                 Vertical Size 
                 Continuous control. Increasing this value 
               
               
                   
                   
                 increases the distance between the top and 
               
               
                   
                   
                 bottom of the image. 
               
               
                   
                   
                 Bipolar setting: 00h=min size 
               
               
                   
                 Horizontal 
                 Continuous control. Increasing this value 
               
               
                   
                 Position 
                 moves the image toward the right side of the 
               
               
                   
                   
                 display. 
               
               
                   
                   
                 Bipolar setting: 00h=max left 
               
               
                   
                 Horizontal Size 
                 Continuous control. Increasing this value 
               
               
                   
                   
                 increases the distance between the left and right 
               
               
                   
                   
                 sides of the image. 
               
               
                   
                   
                 Bipolar setting: 00h=min size 
               
               
                   
                 Overscan 
                 Non-continuous control. This control is used to 
               
               
                   
                   
                 switch the display into an overscan mode. 
               
               
                   
                   
                 Note: The display should always power-up 
               
               
                   
                   
                 into an underscanned mode. The display 
               
               
                   
                   
                 should not go into an overscanned mode until 
               
               
                   
                   
                 instructed to do so by the PC. 
               
               
                   
                 Volume 
                 Continuous control. Increasing this value 
               
               
                   
                   
                 causes the volume in the left and right audio 
               
               
                   
                   
                 channels to increase. 
               
               
                   
                   
                 Unipolar setting: 00h=mute 
               
               
                   
                 Balance 
                 Continuous control. Increasing this value 
               
               
                   
                   
                 maximizes the volume in the right audio 
               
               
                   
                   
                 channel and the volume in the left audio 
               
               
                   
                   
                 channel is decreased. 
               
               
                   
                   
                 Bipolar setting: 00h=max left channel, min 
               
               
                   
                   
                 right channel 
               
               
                   
                   
               
             
          
         
       
     
     The controls in Table 9 are recommended for PC Theatre functionality in addition to the controls listed in the previous tables. It should be noted that some controls do not apply to flat panel technologies. 
     
       
         
               
             
               
               
             
           
               
                 TABLE 9 
               
             
             
               
                   
               
               
                 Additional Display Controls for PC Theatre 
               
             
          
           
               
                 COMMAND 
                 DESCRIPTION/VALUE 
               
               
                   
               
               
                 Tilt control 
                 Continuous control. Increasing this value rotates the 
               
               
                   
                 image in a clockwise direction. 
               
               
                   
                 Bipolar setting: 00h=max counter clockwise 
               
               
                 Color 
                 Continuous or non-continuous control. This control 
               
               
                 Temperature 
                 is used to change the color temperature of the 
               
               
                   
                 display. 
               
               
                 TV Mode 
                 Non-continuous control. This control is used to 
               
               
                   
                 switch the display into a mode that enhances the 
               
               
                   
                 video for watching TV. 
               
               
                 Stand Alone Mode 
                 Non-continuous control. This control is used to 
               
               
                   
                 switch the display from a stand-alone mode to a 
               
               
                   
                 slave mode. 
               
               
                   
                 Stand-alone mode: 
               
               
                   
                 1. Generate OSD internally 
               
               
                   
                 2. Process user input internally 
               
               
                   
                 3. Disable USB control interface 
               
               
                   
                 Slave mode: 
               
               
                   
                 1. Disable OSD 
               
               
                   
                 2. Pass all user input to PC for processing 
               
               
                   
                 3. Enable USB control interface 
               
               
                 Disable On Screen 
                 Non-continuous control. This control is used to 
               
               
                 Display (OSD) 
                 enable the OSD when in slave mode. This is to 
               
               
                   
                 allow the display to generate the OSD instead of the 
               
               
                   
                 PC. 
               
               
                   
               
             
          
         
       
     
     For a complete list of additional controls, the VESA Monitor Control Command Set (MCCS) Standard V1.0 may be consulted. It should also be noted that an address block has been reserved for manufacturer specific controls in this standard. 
     In this embodiment, the PC  14  supports all CRT controls listed in Table 8, as well as all additional controls listed in Table 9. Support for these controls on the PC  14  includes the ability to query the display  12  for supported controls over USB, configure and present a user interface, and send control commands to the display  12  over USB. The display  12  does not store the control settings used for each mode, as the PC  14  will update the display settings after each mode change. 
     The user input from the display&#39;s front button panel and remote control is passed back to the PC  14 , via USB for processing according to the USB Class Definition for Human Interface Devices (HID) specification V1.0 and the USB HID Usage Tables specification V1.0. Sending all user input to the PC  14  for processing allows the display  12  and PC  14  to act as one system with a common user interface. A front button panel and IR receiver is used to operate as USB devices. Note that this does not mean the front button panel and IR receiver have to be actual USB devices. The display  12  may only present a USB control interface to the PC  14 , but may control these devices internally with an I 2 C or other type of control bus. 
     The communication between the PC  14  and the display&#39;s button panel and IR receiver may be standardized to insure compatibility. The USB Class Definition for Human Interface Devices (HID) specification V1.0 defines the communication and the USB HID Usage Table specification V1.0 specifies the address values to be used for each control. Refer to these specifications for more information. Note the manufacturer is free to use any IR or RF protocol for wireless input devices, as they are not specified in this standard. 
     For PC Theatre functionality, the input controls in Table 10 are supported on the PC  14 . Support for these user controls includes the ability to receive these controls over USB, decode the control commands according to the USB HID Usage Table specification V1.0, present the appropriate user interface, and respond to the control either internally or send a control command to the display. It is advantageous for the controls listed in Table 10 to be supported by the PC  14 , although the PC  14  may also support additional control codes. 
     
       
         
               
             
               
               
             
           
               
                 TABLE 10 
               
             
             
               
                   
               
               
                 Display Support for HID 
               
             
          
           
               
                 USAGE NAME 
                 DESCRIPTION 
               
               
                   
               
               
                 Digits 0-9 
                 Digits for the random selection of television 
               
               
                   
                 channels or other applications. 
               
               
                 Volume UP/DOWN 
                 Volume Control. 
               
               
                 Channel UP/DOWN 
                 Sequential channel changing via Up/Down 
               
               
                   
                 commands. 
               
               
                 Power 
                 Power control for system. Power down does not 
               
               
                   
                 necessarily represent lack of system power. 
               
               
                 Mute 
                 Instant volume mute. 
               
               
                 Menu 
                 Initiates on-device-display main menu. Sets a 
               
               
                   
                 mode where the other menu controls are active. 
               
               
                   
                 A subsequent menu press will cancel the mode. 
               
               
                 Menu Pick 
                 Pick item from an on -screen menu. 
               
               
                 Menu 
                 Menu navigation controls. 
               
               
                 UP/DOWN/LEFT/RIG 
               
               
                 HT 
               
               
                   
               
             
          
         
       
     
     The VESA Display Power Management Signaling (DPMS) Standard V1.1 may specify the operation of low power states in the display  12 , and DPMS can be used by the PC  14  to control the power state of the display  12 . The modes of DPMS are ON, STANDBY, SUSPEND, and ACTIVE-OFF. When both the horizontal and vertical syncs are active, the display  12  is fully active and in the ON state. The display  12  enters the STANDBY state when only the vertical sync is active. In this mode, the screen is blanked, but the display  12  remains fully active. The display  12  enters the SUSPEND state when only the horizontal sync is active. In this mode, the display  12  either enters a very low power state or the ACTIVE-OFF state. In the ACTIVE-OFF state, neither the horizontal nor vertical syncs are active. In this mode, the display&#39;s electronics should be completely shut down, with the exception of the microcontroller, USB interface, and IR receiver. If both of the syncs are restored, the display  12  enters the ON state. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 11 
               
             
             
               
                   
               
               
                 DPMS Modes 
               
             
          
           
               
                   
                   
                   
                   
                 POWER 
               
               
                 STATE 
                 H SYNC 
                 V SYNC 
                 REQUIREMENT 
                 SAVINGS 
               
               
                   
               
               
                 On 
                 Active 
                 Active 
                 Mandatory 
                 None 
               
               
                 Standby 
                 No 
                 Active 
                 Mandatory-PC Only 
                 Minimal 
               
               
                 Suspend 
                 Active 
                 No 
                 Mandatory-PC Only 
                 Substantial 
               
               
                 Off 
                 No 
                 No 
                 Mandatory 
                 Maximum 
               
               
                   
               
             
          
         
       
     
     In this embodiment, the PC  14  supports all four DPMS states (ON, STANDBY, SUSPEND, and ACTIVE-OFF). The PC  14  reads the EDID data from the display  12  to determine the supported DPMS modes. For digital displays that only support ACTIVE-OFF, it is recommended that the TMDS transmitter be turned off for all DPMS modes. 
     The display advantageously provides DPMS support as well. To provide a minimum level of support, the display  12  would include only two modes: a fully active mode and a low power mode. Of course, but fill support of DPMS by the display is typically advantageous. 
     The display  12  monitors the vertical sync line. If this sync line is active, the display  12  is fully active for the ON and STANDBY modes. If the vertical sync is not active, the display  12  enters a low power state to support SUSPEND and ACTIVE-OFF modes. In this low power mode, the power LED on the front panel is extinguished (or changes color) and the microcontroller, USB interface, and IR receiver remain active. The USB Specification V1.1 may be consulted for information about USB power management. 
     Both analog and digital displays go into a low power state if any of the video data or timing signals are out of range or are invalid. It is recommended that an OSD be used to communicate the problem to the consumer. 
     The PC Theatre display  12  and PC  14  support two modes of operation: TV and PC. Each mode is advantageously configured for the best video quality of the mode. For example, the PC mode is displayed with the best settings for computer graphics, and the TV mode is displayed with the best settings for TV video. Special video enhancements may be used in TV mode for video that is more like that of a standard TV. Examples of such video enhancements are velocity scan modulation, white peaking, black stretch, and flesh tone correction. The Display-Mode control in the VESA Monitor Control Command Set (MCCS) Standard V1.0 may be used by the PC  14  to enable these display video enhancements in TV mode and disable them in PC mode. Table 12 contains the typical video modes supported by both the PC  14  and display  12 . 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 12 
               
             
             
               
                   
               
               
                 Video Modes 
               
             
          
           
               
                   
                 Horizontal 
                 Vertical 
                   
               
               
                 Format 
                 Frequency (kHz) 
                 Frequency (Hz) 
                 Standard Type 
               
               
                   
               
             
          
           
               
                 640 × 350 
                 31.5 
                 70 
                 Industry Standard 
               
               
                 640 × 400 
                 31.5 
                 70 
                 Industry Standard 
               
               
                 720 × 400 
                 31.5 
                 70 
                 Industry Standard 
               
               
                 640 × 480 
                 31.5 
                 59.95, 60 
                 Industry Standard 
               
               
                 720 × 480 
                 31.5 
                 59.94 
                 VESA (proposed) 
               
               
                   
               
             
          
         
       
     
     In addition to the video modes listed in Table 12, support of the video modes listed in Table 13 may also be considered for the PC Theatre PC  14  and display  12 . 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 13 
               
             
             
               
                   
               
               
                 Additional Video Modes 
               
             
          
           
               
                   
                 Vertical Frequency 
                   
               
               
                 Format 
                 (Hz) 
                 Standard Type 
               
               
                   
               
               
                 640 × 480 
                 72, 75, 85 
                 VESA 
               
               
                 720 × 576 
                 50 
                 IEC 1146 
               
               
                 (for PAL support) 
                   
                 ITU-R Report 624-4 
               
               
                 800 × 600 
                 59.94, 60, 72, 75, 85 
                 VESA 
               
               
                 1024 × 768  
                 59.94, 60, 70, 75, 85 
                 VESA 
               
               
                 1280 × 1024 
                 59.94, 60, 75, 85 
                 VESA 
               
               
                   
               
             
          
         
       
     
     Digital TV support is recommended for both the PC Theatre PC  14  and display  12 . The ATSC specifications may be consulted for information about the digital television formats. Although detailed information about video modes is beyond the scope of this specification, the following standards may be studied for more information about the video modes listed in Tables 12 and 13: VESA Display Monitor Timing Specifications (DMTS), Version 1.7, Dec. 18, 1996; Digital Television Standard for HDTV Transmission, ATSC A/53, 1995; Guide to the Use of the Digital Television Standard for HDTV Transmission, ATSC A/54, 1995; Program for System Information for Terrestrial Broadcast and Cable, ATSC A/65, 1997; Basic Parameter Values For The HDTV Standard For The Studio And For International Programme Exchange—Section 11A—Characteristics of Systems for Monochrome and Colour Television, ITU-R BT.709, 1990; National Television Standards Committee (NTSC), ITU-R Report 624-4, 1990; and PAL (Phase Alternating Line), Video Cameras (PAL/SECAM/NTSC)—Methods of Measurement—Part 1: Non-Broadcast, Single-Sensor Cameras, First Edition, IEC 1146; ITU-R Report 624-4, 1994. 
     Advantageously, the PC  14  and the display  12  share resources to prevent unnecessary duplication of components. For example, if the display  12  has an optional television tuner, the PC  14  can make use of this device to provide Picture-In a-Picture (PIP) functionality. The display  12  can support software control of the tuner and a video multiplexer via USB. The PC  14  sends USB commands to the tuner, and uses the Output Source Select  1  control in the VESA Monitor Control Command Set (MCCS) Standard V1.0 to select it as the output video source. The composite video is sent to the PC  14  through a separate cable to the Composite Video input connector 
     The PC  14  and the display  12  may also support USB television tuner controls that allow the PC  14  to control the tuner  12  in the display. For these controls the channel map is stored and controlled by the PC  14 . 
     The use of the display&#39;s connector panel by the PC  14  greatly increases the flexibility and expandability of the system. If the desired video source is connected to the display  12 , the PC  14  can select the source via USB with the Output Source Select  1  control in the VESA Monitor Control Command Set (MCCS) Standard V1.0 and receive the composite video through separate cable to the Composite Video input connector. 
     The PC  14  and the display  12  have many possible configurations depending upon the price-point and level of functionality required. Two possible configurations are described herein. The first configuration is a minimalistic configuration for PC Theatre functionality, while the second configuration includes additional support that may be included for full PC Theatre functionality. 
     The block diagram in FIG. 8 illustrates the PC Theatre system  10  in the first configuration. The key subsystems of the display  12  are represented as blocks in order to simplify the diagram. The display electronics  80  represents all the functionality of a standard VGA monitor. The control electronics  82  is coupled to the display electronics  80  by an I 2 C bus  84 , and it represents the display microcontroller communication and control functionality. The USB hub  86  is shown to be part of the control electronics  82  as this functionality can be integrated into the main display microcontroller. The control electronics  82  is coupled to an audio amplifier  88  by a USB bus  90 , which in turn is coupled to a left speaker  92  and a right speaker  94 . 
     The control electronics  82  may receive input signals from a control panel  96 , and input and output signals may pass to a from the control electronics via the USB hub  86  which is coupled to the appropriate P&amp;D connector  32  or  34  via a USB and DDC interface  98 . The display electronics  80  may receive command signals from the control electronics  82  via the I 2 C bus  84  or from the PC  14  directly via an RGB interface  100  that is coupled to the P&amp;D connector  32  or  34 . 
     The PC  14  includes an A/V subsystem with tuner  102  that receives input signals from various A/V inputs  104 . The A/Y subsystem  102  is coupled to the P&amp;D connector  30  via an A/V interface  106 . The PC  14  also includes a root USB hub  108  that is coupled to the P&amp;D connector  30  via a USB interface  110  and that is also coupled to USB ports  112 . 
     As can be seen from FIG. 8, in the first configuration, the PC  14  supports the following functionality: 
     USB (12 Mb/s) 
     Audio (USB and Analog) 
     P&amp;D-A/D connector with signals support listed in Table 3 
     A/V subsystem 
     The PC  14  also supports a root USB hub  108  and the software for 12 Mb/s USB functionality. The PC  14  supports the USB Monitor Control Class Specification V1.0 and VESA Monitor Control Command Set (MCCS) Standard V1.0 for software control of the display  12  by the PC  14 . This control of the display  12  includes querying the monitor for supported controls, configuring to support all controls, and providing a user interface to allow the consumer to adjust the display settings. The PC  14  also supports the USB Class Definition for Human Interface Devices (HID) specification V1.0, and the USB HID Usage Tables specification V1.0 for transportation of user input from the display  12  back to the PC  14 . In addition, the PC  14  supports the USB Device Class Definition for Audio Devices specification V1.0 and USB Device Class Definition for Audio Data Formats specification V1.0 for the support of USB to transport audio. 
     In regard to audio, the PC  14  supports both USB and analog stereo audio output to the display  12 . For USB Audio, the PC  14  is capable of sending uncompressed linear 16-bit stereo audio to the display via USB according to the USB Device Class Definition for Audio Data Formats specification V1.0. The PC  14  first queries the display  12  to determine if USB audio is supported before this functionality is enabled. The PC  14  also supports a line-level analog audio output. The connector for this output may be a 3.5 mm stereo audio jack. The PC  14  controls the display&#39;s audio amplifier  88  via USB for both USB and analog audio monitors according to the USB Device Class Definition for Audio Devices specification V1.0. 
     The PC&#39;s A/V subsystem  102  is capable of combining PC and TV video sources and sending the combined video to the display  12 . This ANV subsystem  102  is capable of processing video and audio from the optional internal tuner, an optional tuner in the display  12 , and input through the rear connector panel. The PC  14  also supports at least one Composite video input connector, as well as two 3.5 mm stereo jacks for input and output of line-level stereo audio. 
     In this first configuration, the display  12  supports the following functionality: 
     USB Control (1.5 Mb/s) 
     Analog Audio Amplifier 
     Standard VGA monitor electronics 
     The display  12  also supports 1.5 Mb/s USB functionality to enable control by the PC  14 . Note that the support of 1.5 Mb/s does not allow down-stream USB connectors or audio to be supported. The display  12  further provides a standard HID monitor control interface to the PC  14  according to the USB Monitor Control Class Specification V1.0 and is capable of reporting supported controls, reporting current status, and receiving control commands from the PC  14 . 
     The display  12  also may include a stereo audio amplifier  88  to process analog audio received from the PC  14 . For analog audio input, the display  12  supports two RCA audio connectors on the back panel, and analog audio typically utilizes an additional cable between the PC  14  and display  12 . The audio amplifier  88  acts as a separate USB device and follows the requirements of the USB Device Class Definition for Audio Devices specification V1.0. 
     The display  12  supports the video electronics of a standard monitor. The display  12  receives either analog RGB video or digital TMDS video through the appropriate P&amp;D connector  32  or  34  and displays the video according to the user settings. 
     The block diagram in FIG. 9 illustrates the PC Theatre system  10  in the second configuration. Like FIG. 8, the key subsystems of the display  12  are represented as blocks in order to simplify the diagram. Also, in the interest of clarity, reference numerals of previously discussed elements are used to designate like elements illustrated in FIG.  9 . The it display electronics  80  represents all the functionality of a standard VGA monitor. The control electronics  82  is coupled to the display electronics  80  by an I 2 C bus  84 , and it represents the display microcontroller communication and control functionality. The USB hub  86  is shown to be part of the control electronics  82  as this functionality can be integrated into the main display microcontroller. The control electronics  82  is coupled to an audio amplifier  88  by a USB bus  90 , which in turn is coupled to a left speaker  92  and a right speaker  94 . 
     The A/V electronics  120  represents additional functionality that has been added to the display  12  to support stand-alone TV functionality. The ANV electronics  120  may be coupled directly to the control electronics  82  by an I 2 C interface  122 , or the A/V electronics may be coupled to a tuner  124  which is coupled to the control electronics  82  by an I 2 C interface  126 . The A/V electronics may also receive or transmit signals via the AN ports  128 . 
     The control electronics  82  may receive input signals from a control panel  96 , and input and output signals may pass to a from the control electronics via the USB hub  86  which is coupled to the appropriate P&amp;D connector  32  or  34  via a USB and DDC interface  98 . The display electronics  80  may receive command signals from the control electronics  82  via the I 2 C bus  84  or from the PC  14  directly via an RGB interface  100  that is coupled to the P&amp;D connector  32  or  34 . 
     Like the first configuration, the PC  14  includes an AN subsystem with tuner  102  that receives input signals from various A/V inputs  104 . The ANv subsystem  102  is coupled to the P&amp;D connector  30  via and ANV interface  106 . The PC  14  also includes a root USB hub  108  that is coupled to the P&amp;D connector  30  via a USB interface  110  and that is also coupled to USB ports  112 . In addition to the first configuration, the PC  14  may include a USB port  130  that is coupled to the root USB hub  108 . Also, the PC  14  may include a  1394 _ 132  which receives signals from the  1394  port  134  and transfers these signals to the P&amp;D connector  30 . 
     As can be seen from FIG. 9, in the second configuration, the PC  14  may support the following features that are in addition to the functionality described above in relation to the first confiruation: 
     Additional USB Connectors 
     Additional A/V Connectors 
     Tuner 
     IEEE- 1394  Support 
     In addition to USB support through the P&amp;D connector  30 , the PC  14  may support USB connectors on the front and rear panel through the ports  112  and  130 . In addition to the single Composite Video connector supported in the first configuration, the PC  14  may also support other video connectors (Composite and S-video) on the front and/or rear panels. The PC may also support an internal tuner for watching TV without the need for the tuner  124  in the display  12 . Also, the PC  14  may provide support for IEEE- 1394  to the display  12  through the P&amp;D connector  30 , and the PC  14  may support  1394  connectors on the front and/or rear panels via the  1394  ports  134 . 
     In this second configuration, the display  12  may support the following features that are in addition to the functionality described above in relation to the first configuration: 
     Stand-alone TV Functionality 
     Front Button Panel 
     Remote Control and IR Receiver 
     USB Connectors and Audio Support 
     IEEE- 1394  Support 
     The display  12  may support two modes of operation: stand-alone mode and slave mode. In stand-alone mode, the display  12  operates as a standard TV. In addition to the standard monitor electronics, the display  12  also includes a video and audio subsystem embodied in the ANV electronics  120  capable of providing stand-alone TV functionality. This subsystem may include a tuner or tuners  124 , A/V connectors  128  on the back panel, and video and audio multiplexers. 
     This subsystem has two modes of operation. When in stand-alone mode, this subsystem provides the functionality necessary for stand-alone TV operation. When connected to a PC Theatre PC  14  and in slave-mode, the video from the tuner  124  or A/V connectors may be selected and sent to the PC  14  via the control electronics  82  for processing. In slave mode, the display  12  passes all user input to the PC  14  for processing, disables the On Screen Display (OSD), displays the VGA video from the PC  14 , and responds to USB commands from the PC  14 . 
     The display&#39;s front panel  96  can include buttons for Channel-Up, Channel-Down, Volume-Up, Volume-Down, Menu, Select, Power, etc. These buttons on the front panel have two modes of operation. When the display  12  is in stand-alone mode, the control electronics  82  responds directly to a button press. When the display  12  is connected to a PC Theatre PC  14  and in slave mode, the display  12  sends a USB command to the PC  14  when a button is pressed and does not generate an OSD internally. The USB command may be sent according to the requirements of the USB Class Definition for Human Interface Devices (HID) specification V1.0, and the USB HID Usage Tables specification V1.0. The PC  14  then processes the user input. 
     As mentioned previously, the display  12  may include a remote control and IR or RF receiver. The receiver may also have two modes of operation. When the display  12  is in stand-alone mode, the receiver data from the remote is processed internally. When the display  12  is connected to the PC  14  and in slave mode, the remote button presses are sent as USB commands to the PC  14  according to the requirements of the USB Class Definition for Human Interface Devices (HID) specification V1.0, and the USB HID Usage Tables specification V1.0. The PC  14  then processes the user input. 
     The display  12  may include a 12 Mb/s USB hub and external USB connectors  140  and  142 . The connectors  140  and  142  may be on the front and/or rear panel. Note that USB connectors are typically connected to the PC  14  regardless of the display&#39;s power state (On or Active-Off) and operational mode (stand-alone or slave). The display  12  may also support USB audio. For USB audio support, the audio amplifier  88  receives the uncompressed linear stereo 16-bit USB audio stream through the P&amp;D connector according to the requirements of the USB Device Class Definition for Audio Data Formats V1.0. 
     The display  12  may support IEEE-1394 video processing and connectors  144  on the front and/or rear panel. Note that 1394 connectors are typically connected to the PC  14  regardless of the display&#39;s power state (On or Active-Off) and operational mode (stand-alone or slave). 
     Next, a high level description the operational procedures utilized for the PC  14  and the display  12  is presented to provide PC Theatre functionality and to insure compatibility. The appropriate VESA or USB specification may be consulted for more information. 
     The startup procedures for a PC Theatre system  10  as it initializes itself are described below. The PC Theatre system startup procedures are as follows: 
     Determine if an active display is connected to the system. This is determined by checking to see if the voltage on pin  8  of the P&amp;D connector is greater than +2 VDC. 
     Attempt to read the 256 KB EDID data structure 2.0 at the I 2 C slave address of A2h. 
     If the read was successful, determine if the EDID 2.0 data is valid by checking the checksum of the EDID structure. 
     If the EDID 2.0 data is valid, parse and store the data. 
     With the parsed EDID 2.0 data, configure the video subsystem and activate appropriate video interface (RGB or TMDS). 
     If the attempt to read the EDID 2.0 data fails, attempt to read the 128 KB EDID data structure 1.1 at the I 2 C slave address of A0h. 
     Determine if the EDID 1.1 data is valid by checking the checksum of the EDID structure. 
     If EDID 1.1 data is valid, parse and store data 
     With parsed data, configure the video subsystem and activate the appropriate video interface (RGB or TMDS). For a digital display, assume the default configuration of 24 bit MSB-aligned RGB TFT. 
     If the attempt to read the EDID 1.1 data fails, assume the display does not support DDC and use default RGB video settings. 
     Request status from HID monitor control device via USB. 
     If a valid response is received from the display, request the list of supported controls and the type and range of each control. 
     With the data of supported controls, configure the display control panel user interface. 
     Check the list of monitor supported controls to determine if a tuner is supported. 
     If tuner controls are supported, configure the user interface to use the tuner and configure the video subsystem to receive the video through the Composite video connector. 
     Check the list of monitor supported controls to determine if the Output Source Select control is supported. 
     If this output control is supported, configure the user interface to use the rear connector panel of the display and configure the video subsystem to receive the video through the Composite video connector. 
     Check to see if the default control values of the display are stored internally. 
     If the default values have not been stored internally, restore the default values of the display using the RestoreFactoryDefault or RestoreSaved command (if supported). Read all of the displays picture quality and geometry control settings and store them internally as the defaults. Repeat the process for each supported DisplayMode (Productivity, Games, Movies). 
     Request the status of the USB audio amplifier in the display. 
     If a valid response is received, request the supported audio controls and configure internal audio subsystem to send USB audio to the display using a supported format (compressed, uncompressed, number of channels, etc). 
     If a valid USB response is not received, assume display does not support PC Theatre functionality and disable the user interface. 
     If the display is in Stand-alone mode, use the Display Transition procedures to change the display to Slave mode. 
     Next, the startup procedures for the PC Theatre display  12  as it initializes itself are described below. The display  12  startup procedures are as follows: 
     1. Perform normal initialization procedures for either a standard monitor or TV. 
     2. Set all controls using internally stored settings. 
     3. For a stand-alone TV, set the status of the internal Operation Mode control to Stand-alone and operate as a standard TV. 
     4. If the display does not support stand-alone operation, set the status of the internal Operation Mode control to Slave and operate as a standard monitor. 
     The mode transition procedures are described below for the PC  14  as this device transitions the display  12  from stand-alone mode to slave mode or slave mode to stand-alone mode. The procedures for transitioning the display  12  from stand-alone mode to slave mode are as follows: 
     1. Send an Operation Mode command to the display to switch to Slave mode. This enables the PC to control the display. 
     2. Read back the status of the Operation Mode control. Do not send other USB commands to the display until the status of this control indicates Slave mode. Repeat the read process if necessary. 
     3. Send an Input Source Select command to switch the display to the P&amp;D input. This enables the PC to drive the video input of the display. 
     4. If the computer is in TV mode, and the controls are supported, send a Scan Format command to switch the display to Overscan and a Display Mode command to switch the display to Movies which enables the TV video enhancements. In addition, disable internal screen savers and DPMS operation. 
     5. If the computer is in PC mode, and the controls are supported, send a Scan Format command to switch the display to Underscan and a Display Mode command to switch the display to Productivity which disables the TV video enhancements. 
     6. Send appropriate video quality and geometry commands to the display for the current mode. 
     The procedures for transitioning the display  12  from slave mode to stand-alone mode are as follows: 
     1. Send Operation Mode command to the display to switch to Stand-alone mode. 
     2. Disable USB command communication to the display. 
     The mode transition procedures are described below for the display  12  as it transitions from stand-alone mode to slave mode or slave mode to stand-alone mode. The PC Theatre display procedures for transitioning from stand-alone mode to slave mode are as follows: 
     1. Wait until internal transition is complete before reporting the status of the Operation Mode command as set to Slave. 
     2. Enable the reception of other USB commands from the PC. 
     3. Enable DPMS operation of the display. 
     4. Disable internal processing of user input from remote and front button panel. 
     5. Send all user commands to the PC for processing over USB. 
     6. Disable internal OSD. 
     The procedures for transitioning the display  12  from slave mode to stand-alone mode are as follows: 
     1. Wait until internal transition is complete before reporting the status of the Operation Mode command as set to Stand-Alone. 
     2. Disable the reception of all USB commands except Operation Mode and status from the PC. 
     3. Disable DPMS operation of the display. 
     4. Enable internal processing of user input from remote and front button panel. 
     5. Disable sending all user commands to the PC. 
     6. Enable internal generation of user interface. 
     7. Restore internal default values for picture quality and geometry. 
     8. Switch Input Source Select to Tuner. 
     9. Resume normal TV operation. 
     The normal operation procedure is describe below for a fully active PC  14 . 
     1. Process all user input from keyboard, mouse, gamepad, and display. 
     2. Display the appropriate user interface. 
     3. Control internal subsystems. 
     4. Send control commands to the display. 
     The normal operation procedure is described below for the PC Theatre display  12 . The PC Theatre display  12  normal operation procedures for stand-alone mode are as follows: 
     1. Process all user input internally. 
     2. Display appropriate user interface. 
     3. Send appropriate control commands to internal subsystems. 
     The PC Theatre display normal operation procedures for stand-alone mode are as follows: 
     1. Send all user input to the PC for processing. 
     2. Disable internal display of user interface. 
     3. Disable internal control of display subsystems. 
     The shutdown procedure is described below for a PC Theatre PC  14  as this device transitions to a sleep mode. 
     1. Send Operation Mode command to the display to switch to Stand-alone mode. 
     2. Perform normal shut down procedures for a PC. 
     The shutdown procedure is described below for a PC Theatre display  12  as this device transitions to a sleep mode. 
     1. If the display is in Slave mode, pass the user shutdown command to the PC for processing. 
     2. If the display is in Stand-alone mode, perform normal shutdown procedures. 
     3. Ignore all USB commands from the PC after shutdown. 
     While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.