Background of invention
Accelerated graphics display adapter with higher functionality just is used widely in industry, and these adapters are replacing the VGA adapter gradually as industrial standard.The accelerated graphics adapter has special one's own processor, be used for picture information is sent into memory device, and VGA is to use the processor of system or main frame that picture information is sent into memory device.Just because of have own special-purpose processor, the accelerated graphics adapter is quicker than VGA, efficient is higher.
Yet, because the VGA application program that has existed continues supply VGA adapter and just becomes long-standing demand in the industry.For satisfying such demand, some display adapter manufacturers have designed the accelerated graphics display adapter with VGA function.Fig. 1 has described an accelerated graphics adapter 100 with this VGA function, and it comprises accelerated graphics controller 110 and a VGA port and an input port.Graphics controller 110 is linked a frame buffer zone 130, and frame buffer zone 130 is further linked random access memory digital to analog converter (RAMDAC) 150 again.RAMDAC150 has a display port, and being used for provides image to display monitor 160, also has a VGA port to be used to receive the VGA pictorial data simultaneously.Graphics adapter 100 also comprises a vga controller 120, is connected to the VGA port of accelerated graphics controller 110, the VGA port of RAMDAC150.An and dynamic RAM (DRAM) 140.
The accelerated graphics data that the input port of slave controller 110 receives are accelerated graphics controller 110 and handle and be stored in the frame buffer zone 130.When needs were shown, data were admitted to RAMDAC150, were used for finally showing on watch-dog 160.Be accelerated the VGA data that controller 110 receives, be admitted to vga controller 120 by the VGA port, and be stored among the DRAM140.When DSR shows, retrieved from DRAM140 by vga controller 120, send into RAMDAC150 by the VGA port of RAMDAC150 then.
As shown in Figure 1, for realizing the VGA compatibility, the accelerated graphics adapter uses two memory device-frame buffer zones 130 and DRAM140, and the use of these two memory devices constitutes whole expenses of adapter.
Many times owing to various reasons, the user may wish VGA Display image and acceleration image on screen simultaneously.In this case, every images is displayed in the window.Yet when the image of VGA generation was shown, graphics adapter shown in Figure 1 did not allow to use acceleration controller.More particularly, the use of vga controller has determined the operation of RAMDAC150, RAMDAC operation that VGA controlled and the RAMDAC operation of accelerated graphics control and incompatible.Therefore, simultaneously on a screen VGA Display image and accelerogram like impossible.
Therefore, need a kind of technology, be used to have the VGA function, only use a memory device to come the graphics image display adapter of (comprising the VGA image), show when allowing VGA and accelerated graphics image.
Embodiment
Fig. 2 is by the employed digital machine 200 of the preferred embodiment for the present invention.In the calculating machine frame 205 with input equipment 230 and output device 240, computing machine comprises primary processor 210 and the primary memory 220 that is attached thereto.Input equipment 230 can comprise keyboard, mouse, the input equipment of graphic tablet or other type.Output device 240 can comprise the text watch-dog, the output device of plotting apparatus or other type.Primary processor 210 can also link to each other with graphical output device 310, as the graphic alphanumeric display via graphics adapter 300.Graphics adapter 300 can be arranged in an adapter slot 260A, receives graphics command from primary processor 210 on bus 250.Modulator-demodular unit or other communication adapter 350 and a hard disk 355 also can be positioned on groove 260C and the 260D, and being used for provides and the communicating by letter of primary processor by bus 250.Modulator-demodular unit 350 can be communicated by letter with other data handling system 370 by order wire 360.Primary memory 220, hard disk 355 and floppy disk all are called storer.
The present invention realizes that in graphics adapter 300 Fig. 3 is the part block diagram as the above-mentioned graphics adapter of describing 300 in Fig. 2.These parts comprise and grating mechanism 420 address decoders 480 that link to each other with a vga controller 425 that vga controller 425 also links to each other with grating mechanism 420.Address decoder 480 is used for transmitting data to grating mechanism or vga controller.Address decoder is well-known in this area, and their realization has not just here illustrated.Grating mechanism is defined as producing a specific pictorial data, and which pixel need be updated, and how to upgrade pixel to produce visually demonstration accurately.The pictorial data that vga controller 425 usefulness obtain from processor 210 is upgraded the VGA storer.The part that also has in the graphics adapter 300 is a frame buffer zone 430, but it comprises that a display-memory 432 and one can not display-memories 434.Frame buffer zone 430 links to each other with grating mechanism 420.Vga controller 425 uses and can not store the VGA data by display-memory 434, but display-memory 432 also links to each other with RAMDAC440.
If graphics system is designed to show 1024 * 768 or the 768K byte data, frame buffer zone has the storage capacity of 1024K byte data usually, 768K byte wherein is used to hold the data that are shown the most at last, therefore be called display-memory, do not deposit must data presented for the 256K byte in addition, and therefore being called as can not display-memory.Usually this 256K byte in the storage capacity is not used, and therefore has been wasted.The present invention has used this storage capacity to store the VGA pictorial data effectively, no longer needs other memory device to store these data.Although the present invention uses one to be designed to show that the system of 768K byte data describes, use the system of the pictorial data of different sizes also can use.For example, be designed to show that the system of 1280K byte pictorial data uses the frame buffer zone that 2048 bytes store abilities are arranged, the 768 byte frame buffer zones that are not used are used as the VGA storer.
Traditional VGA memory device or DRAM are divided into 4 grades of maps usually, the different information that each grade map is used to save image.For example under Text Mode, first order map is preserved character code information, and second level map is preserved attribute information, and third level map is preserved font information, and fourth stage map only is used for graphic model usually.Equally, can not be divided into 4 grades of storage mappings by display-memory 434, be used to preserve the different information of VGA image.Although frame buffer zone can not may be divided into 4 grades of maps physically in the display part, it is divided into virtual image in this example.Just, vga controller use addressing mechanism effectively application memory as 4 grades of different maps.For transmitting effectively, the VGA map data combines with independent storer 434 accesses.
In operation, when host-processor 210 when graphics adapter 300 transmits data, decipher to determine that data are sent to grating mechanism 420 or vga controller 425 480 pairs of data addresses of address decoder.The data of importing vga controller 425 into are handled by vga controller, and being sent to then can not display-memory 434 storage.Equally, but the data of importing grating mechanism 420 into are sent to display-memory 432 storages after treatment.When the VGA data need be shown, vga controller 425 was handled to generate image data on request from retrieving data the display-memory 434, then it is sent into grating mechanism 420.But grating mechanism 420 is sent into display-memory 432 to the VGA data, with synthetic VGA image with by any image of grating mechanism 420 generations.Grating mechanism obtains the start address of VGA image window in the required composite image by the primary processor 210 among Fig. 2.But the VGA pictorial data is by map place by start address and the decision of VGA image size in the display-memory 432, and these information are defined by the VGA mode of operation.If desired, can also do transformation of scale, to be suitably for the final screen resolution that display 470 generates to the VGA image.But the data through these processing are admitted to display-memory 432 storages, and when needs were shown, data passed to display 470 by RAMDAC440.
But the pictorial data in the display-memory 432 is presented on the display monitor 470 in the mode of raster scanning.Just, Tu Xiang display mode is that the scanner by the whole display space of display monitor 470 scans line by line with a branch of adjustable electron beam.Accordingly, the pictorial data relevant with the upper left chitin of watch-dog at first provided, and the pictorial data relevant with lower right corner pixel provided at last.After arriving lower right corner pixel, the vertical blanking of electron beam or close is to prevent returning display element in the process in the watch-dog upper left corner at it.At vertical initial stage of blanking, vga controller 425 begins sense data from can not display-memory 434, it is offered grating mechanism 420 handle.But grating mechanism 420 deal with data also store it into display-memory 432.Therefore, before the raster scanning processing procedure of display 470 needed pictorial data, the VGA image in the storer 432 had generated.This just and be that display 470 generates the VGA image synchronously, when having avoided scanning when showing, the situation of image imperfect (part is newly visual, the old image of part) in the storer.Note, but the expedited data in the display-memory 432 all is refreshed when graphics adapter transmits the accelerated graphics data at each primary processor 210.
Fig. 4 has described the detailed diagram that is used for showing the equipment of multiwindow on display monitor.Equipment comprises 510, one window identifier (wid) 530 of graphic process unit and the RAMDAC540 that links to each other with frame buffer zone 520.RAMDAC540 also links to each other with wid530 and frame buffer zone 520.Graphic process unit 510 is included in the grating mechanism 420 of Fig. 3, and it is wanting data presented (VGA and accelerated graphics) to pass to frame buffer zone 520 by data bus 570.Graphic process unit 510 is also delivered to wid530 by address bus 580 transmitting several addressing informations.Palette among the LUT545 is upgraded by graphic process unit 510 by control bus 560.
But wid530 and display-memory 520 are shone upon in the same manner, and just, each position among the wid530 is corresponding to a pixel location in the storer 520.The code that wid530 produces is used for determining the attribute of corresponding pixel by RAMDAC540, as the color depth of pixel etc.RAMDAC540 uses these attributes to come for the correct interpretation of a certain certain window selection to data, as the figure place of each pixel, palette address etc.Like this, VGA pictorial data and accelerogram image data can be simultaneously displayed on the display monitor, respectively in separately pixel interpretation mode in window separately.For example, the VGA data of 8 of every pixels can together show with the acceleration image of 16 of every pixels.
Although described the present invention with reference to specific implementations, to those skilled in the art, clearly also have other embodiments.Therefore, as above explanation can not be considered as limitation of the scope of the invention, and scope of the present invention is determined by claims.