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The DEVICECONTEXT structure is a device-dependent structure internal to
grabbers. Its layout, content, and length will vary from grabber to
grabber.
 
The following is the DEVICECONTEXT structure for the grabbers for Hercules
adapters:
 
DeviceContext struc
    dcScrMode       db  ?   ;BIOS screen mode
    dcScrStart      dw  ?   ;regeneration of start position
    dcCursorPosn    dw  ?   ;cursor position in CRTC format
    dcCursorMode    dw  ?   ;cursor start/stop scan lines
    dcModeCtl       db  ?   ;3x8 mode register data
    dcExModeCtl     db  ?   ;3xx extended-mode register data
    dcColorSelect   db  ?   ;3D9 color select register data
    dcCrtcParms     dw  ?   ;-> CRTC parameters for non-BIOS modes
    dcfSwitchGmt    db  ?   ;switch graphics/multiple text
DeviceContext ends
 
The following is the DEVICECONTEXT structure for EGA grabbers:
 
DeviceContext struc
    dcScrMode       db  ?           ;BIOS screen mode
    dcScrStart      dw  ?           ;regeneration of start position
    dcCursorPosn    dw  ?           ;cursor position in CRTC format
    dcCursorMode    dw  ?           ;cursor start/stop scan lines
    dcAddrPatch     db  ?           ;3Dx / 3Bx patch byte
    dcfSwitchGmt    db  ?           ;switch graphics/multiple text
    dcFileNum       dw  ?           ;-> random number in swap file
    dcFontBank      db  4  dup (?)  ;ERI font information
    dcSwapPath      db  64 dup (?)  ;full swap path
DeviceContext ends
 
The following is the DEVICECONTEXT structure for VGA grabbers:
 
DeviceContext   struc
    dcScrMode       db  ?           ;BIOS screen mode
    dcScrStart      dw  ?           ;regeneration of start position
    dcCursorPosn    dw  ?           ;cursor position in CRTC format
    dcCursorMode    dw  ?           ;cursor start/stop scan lines
    dcAddrPatch     db  ?           ;3Dx / 3Bx patch byte
    dcfSwitchGmt    db  ?           ;switch graphics/multiple text
    dcFileNum       dw  ?           ;-> random number in swap file
    dcFontBank      db  8  dup (?)  ;VGA has 8 font banks
    dcSwapPath      db  64 dup (?)  ;full swap path
DeviceContext   ends
 
 
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