chips.txt

比较详尽的VGA端口寄存器的文档

         If set CRT registers (3d4h) index: 7 bit 4, 8, 11h bits 4-5,
         13h, 14h, 17h bits 0-1 and 3-7, 18h are write protected.
      3  Write Protect Group 4 Registers.
         If set CRT registers (3d4h) index: 9 bits 5-7, 10h, 11h bits 0-3
         and 6-7, 12h, 15h, 16h, 17h bit 2 are write protected.
      4  Write Protect Group 5 Register.
         If set the Miscellaneous Output (3C2h) and Feature Control
         (3dAh) registers are write protected.
      5  Write Protect Group 6 Registers.
         If set the DAC registers (3C6h-3C9h) are write protected.
      6  Write Protect Group 0 Registers.
         If set CRT registers (3d4h) index: 0, 1, 2, 3, 4, 5, 6,
         7 bits 0-3 and 5-7 are write protected.

3d6h index 16h (R/W):  Trap Enable Register.                       (not 655x0)
bit   0  If set accesses to registers 3B4h or 3B5h cause a Trap.
      1  If set accesses to registers 3B8h or 3BFh cause a Trap.
      2  If set accesses to registers 3C0h-3CFh cause a Trap.
      3  If set accesses to registers 3D4h or 3D5h cause a Trap.
      4  If set accesses to registers 3D8h or 3D9h cause a Trap.
      5  If set accesses to registers 3d4h index 0-0Bh and 10h-18h
         cause a Trap.

3d6h index 17h (R/W):  Trap Status Register.                 (not 64300,655x0)
bit   0  If set a trap occurred due to access to registers 3B4h or 3B5h.
      1  If set a trap occurred due to access to registers 3B8h or 3BFh.
      2  If set a trap occurred due to access to registers 3C0h-3CFh.
      3  If set a trap occurred due to access to registers 3D4h or 3D5h.
      4  If set a trap occurred due to access to registers 3D8h or 3D9h.
      5  If set a trap occurred due to access to registers
         3d4h index 0-0Bh or 10h-18h.
Note: Any bits in this register can be cleared by writing a 1 bit to them.

3d6h index 17h (R/W):                                                  (64300)
bit   0  Bit 8 of the Horizontal Total. Bits 0-7 are in 3d4h index 0.

3d6h index 18h (R/W):  Alternate Horizontal Display Enable End Register
bit 0-7  This register replaces the Horizontal Display Enable End Register
         (3d4h index 1) in low resolution CGA text and graphics modes,
         Hercules Graphics and all flat panel modes.
Note: Probably doesn't exist in the 82c451/2/3.

3d6h index 19h (R/W):  Alternate Horizontal Sync Start Register
bit 0-7  This register replaces the Horizontal Sync Start Register (3d4h index
          4) in low resolution CGA text and graphics modes, Hercules Graphics
         and all flat panel modes.
Note: Probably doesn't exist in the 82c451/2/3.

3d6h index 1Ah (R/W):  Alternate Horizontal Sync End Register
bit 0-4  Alternate Horizontal Sync End. Replaces 3d4h index 5 bits 0-4.
    5-7  Alternate Horizontal Sync Delay.
         For CRTs replaces 3d4h index 5 bits 5-6.
Note: This register replaces the Horizontal Sync End Register (3d4h index 5)
      in low resolution CGA text and graphics modes, Hercules Graphics and
      all flat panel modes.
Note: Probably doesn't exist in the 82c451/2/3.

3d6h index 1Bh (R/W):  Alternate Horizontal Total Register
bit 0-7  This register replaces the Horizontal Total Register
         (3d4h index 0) in low resolution CGA text and graphics modes,
         Hercules Graphics and all flat panel modes.
Note: Probably doesn't exist in the 82c451/2/3.

3d6h index 1Ch (R/W):  Alternate Horizontal Blank Start Register         (CRT)
bit 0-7  Alternate Horizontal Blank Start.
Note: For CRT systems this register replaces the Horizontal Blank Start
      Register (3d4h index 2) in low resolution CGA text and graphics
      modes and Hercules Graphics mode.
Note: Probably doesn't exist in the 82c451/2/3.
Note: This register has different meaning for CRT and Plat Panel systems.

3d6h index 1Ch (R/W):  Alternate Horizontal Blank End Register    (Flat Panel)
bit 0-7  For Flat Panel systems this value specifies the end of Horizontal
         Blank in terms of character clocks.
Note: Probably doesn't exist in the 82c451/2/3.
Note: This register has different meaning for CRT and Plat Panel systems.

3d6h index 1Dh (R/W):  Alternate Horizontal Blank End Register           (CRT)
bit 0-4  Alternate Horizontal Blank End
    5-6  Alternate Display Enable Skew Control.
Note: For CRT systems this register replaces the Horizontal Blank End
      Register (3d4h index 3) in low resolution CGA text and graphics
      modes, and Hercules Graphics mode.
Note: Probably doesn't exist in the 82c451/2/3.
Note: This register has different meaning for CRT and Plat Panel systems.

3d6h index 1Dh (R/W):  Alternate Horizontal Blank Start Register (Flat Panel)
bit 0-7  Alternate Horizontal Blank Start.
Note: For Flat Panel systems this register replaces the Horizontal Blank
      Start Register (3d4h index 2).
Note: Probably doesn't exist in the 82c451/2/3.
Note: This register has different meaning for CRT and Plat Panel systems.

3d6h index 1Eh (R/W):  Alternate Offset Register
bit 0-7  Alternate Offset.
Note: This register replaces the Offset Register (3d4h index 13h) in low
      resolution CGA text and graphics modes and Hercules Graphics mode.
Note: Probably doesn't exist in the 82c451/2/3.

3d6h index 1Fh (R/W):  Virtual EGA Switch Register                (655x0 only)
bit 0-3  If bit 7 is 1 one of these bits is read back in the Input Status
         Register 0 (3C2h bit 4) depending on Miscellaneous Output bits 2-3:
          0: bit 3, 1: bit 2, 2: bit 1, 3:bit 0.
      7  If set one of bits 0-3 is read back in the Input Status Register
         (3C2h) bit 4.

3d6h index 20h (R/W):  Sliding Unit Delay                         (452/3 only)

3d6h index 21h (R/W):  Sliding Hold A                               (452 only)

3d6h index 22h (R/W):  Sliding Hold B                               (452 only)

3d6h index 23h (R/W):  Write Mask Control                         (452/3 Only)
bit   0  Enable VRAM Write Mask function if set
    1-2  Write Bit Mask Select:
          0: Write Bit Mask Pattern Register (3d6h index 24h)
          1: Graphics Controller Bit Mask    (3CEh index 8)
          2: Rotated CPU byte
      3  Enable Fast Read/Modify/Write function if set

3d6h index 24h (R/W):  Write Bit Mask Pattern                  (82c452/3 only)
bit 0-7  Write Bit Mask (if 3d6h index 23h bit 1-2 =0)

3d6h index 24h (R/W):  Alternate Maximum Scanline Register        (655x0 only)
bit 0-4  Number of scanlines -1 per character row of TallFont.
Note: Used in Flat Panel text modes when TallFont is enabled.

3d6h index 25h (R/W):  FP AltGrHVirtPanel Size               (453, 655x0 only)
bit 0-7  Should be: (9/8)*(3d6h index 1Ch +1) -1.

3d6h index 26h (R/W):  Configuration                             (82c453 Only)
bit   0  PC/AT if set, PS/2 if not
    1-2  VRAM memory
          0: 512k   16 chips of  64k x4
          1: 512k    4 chips of 256k x4
          2:   1M    8 chips of 256k x4
          3: 512k    8 chips of  64k x4  ?????  maybe 256k ??

3d6h index 27h (R/W):  Force Sync State

3d6h index 28h (R/W):  Video Interface
bit   0  BLANK/Display Enable Polarity.
         Positive if set, Negative if clear.
      1  Blank /Display Enable Select (CRT).
         If set the BLANK/ pin outputs DE, if clear BLANK/
      2  Shut Off Video.
         If set the video signal is forced to default video
         (3d6h index 2bh) during the blanking interval.
      3  Shut Off Blank.
         If set the BLANK/ output is forced active
         during the blanking interval.
         (655x0)  Read/writable, but has no function.
      4  (655x0)  256 Color Video Path.
           If set Video Data Path is 8 bits rather than 4 bits.
         (64300)  Set in 256c or Hi/Truecolor modes, clear all other modes
      5  (655x0)  Interlace Video. CRT graphics modes only.
         If set Video is interlaced.
      6  (655x0)  8-bit Video Pixel Panning.
         If set 3C0h index 13h bits 0-2 are used to control
         pixel panning rather than bits 1-2.
      7  (655x0)  Read/writable, but has no function.

3d6h index 29h (R/W):  External Sync Control                        (452 only)

3d6h index 2Ah (R/W):  Frame Interrupt Count                        (452 Only)
bit 0-4  Generate Vertical Interrupt every (n+1) frames

3d6h index 2Bh (R/W):  Default Video Register                        (not 453)
bit 0-7  On CRTs this is the color displayed during blank time.

3d6h index 2Ch (R/W):  FP Vsync (FLM) Delay Register.
bit 0-7  Number of Hsync pulses between internal Vsync and the
         rising edge of First Line Marker (FLM).
Note: Only used in Flat Panel modes when 3d6h index 2Fh bit 7 is 0..

3d6h index 2Dh (R/W):  FP Hsync (LP) Delay Register.
bit 0-7  Number of character clocks between the FP Blank inactive
         edge and the rising edge of the LP.
Note: Only used in Flat Panel modes when 3d6h index 2Fh bit 6 is 0 and
      graphics mode horizontal compression is disabled.

3d6h index 2Eh (R/W):  FP Hsync (LP) Delay Register.
bit 0-7  Number of character clocks between the FP Blank inactive
         edge and the rising edge of the LP.
Note: Only used in Flat Panel modes when 3d6h index 2Fh bit 6 is 0
      and 9 dot text mode is used.

3d6h index 2Fh (R/W):  FP Hsync (LP) Width Register
bit 0-3  Width of the LP output pulse in number of character clocks.
         Only in 8 dot text modes on Flat Panels.
      4  Bit 8 of the FP Hsync (LP) Delay Register (3d6h index 2Eh).
      5  Bit 8 of the FP Hsync (LP) Delay Register (3d6h index 2Dh).
      6  FP Hsync (LP) Delay Disable.
         If set the FP Hsync (LP) active edge will coincide with the
         FP Blank inactive edge.
      7  FP Vsync (FLM) Delay Disable.
         If set the external FP Vsync (FLM) will coincide with
         the internal FP Vsync (FLM) active edge.

3d6h index 30h (R/W):  Graphics Cursor Start Address High           (452 only)
bit 0-7  Bit 8-15 of the Cursor Start Address.

3d6h index 31h (R/W):  Graphics Cursor Start Address Low            (452 only)
bit 0-7  Lowest 8 bits of the Cursor Start address. 3d6h index 30h and index
         Ah forms the upper 10 bits. In 256 color modes this address has a
         granularity of 16 bytes and 4 bytes in 16 color modes.

3d6h index 31h (R/W):  Clock Numerator                                 (64300)
bit 0-6  If 3C2h/3CCh bits 2-3 is 2 or 3 the clock is determined by this and
         the next index. Clock = 2*RefClk*(index 31h +a)/(index 32h +b).
         RefClk is normally 14.18318. a and b are small constants that must be
         added. For now I use 2 for both.

3d6h index 32h (R/W):  Graphics Cursor End Address                  (452 only)
bit 0-7  End address of the cursor bit map.

3d6h index 32h (R/W):  Clock Denominator                               (64300)
bit 0-6  See index 31h for details.

3d6h index 33h (R/W):  Graphics Cursor X Position High              (452 only)
bit 0-3  Bits 8-11 of the X co-ordinate of the cursor.

3d6h index 34h (R/W):  Graphics Cursor X Position Low               (452 only)
bit 0-7  Lower 8 bits of the X co-ordinate of the cursor.

3d6h index 35h (R/W):  Graphics Cursor Y Position High              (452 only)
bit 0-3  Bits 8-11 of the Y co-ordinate of the cursor.

3d6h index 36h (R/W):  Graphics Cursor Y Position Low
bit 0-7  Lower 8 bits of the cursor Y co-ordinate.

3d6h index 37h (R/W):  Graphics Cursor Mode                         (452 only)
bit   0  Cursor Enabled if set
      1  Cursor Status enable
      2  Horizontal Zoom. Zoom to 64 pixels wide if set.
         (Normally 32 pixels wide).
      3  Cursor Blink enabled if set
      4  Cursor Blink Rate. 8 frames if clear, 16 if set

3d6h index 38h (R/W):  Graphics Cursor Plane Mask                   (452 only)
bit   0  Enables graphics cursor in bit plane 0 if set
      1  Enables graphics cursor in bit plane 1 if set
      2  Enables graphics cursor in bit plane 2 if set
      3  Enables graphics cursor in bit plane 3 if set

3d6h index 39h (R/W):  Graphics Cursor Color 0                      (452 only)
bit 0-7  Background color of Graphics Cursor.

3d6h index 3Ah (R/W):  Graphics Cursor Color 1                      (452 only)
bit 0-7  Foreground color of Graphics Cursor.

3d6h index 44h (R/W):  Scratch #0 Register                (82c453, 655x0 Only)
bit 0-7  Available

3d6h index 45h (R/W):  Scratch #1/Foreground Color               (82c453 Only)
bit 0-7  Used as foreground color if in Fast Font Paint mode,
         Available as scratch if not.

3d6h index 50h (R/W):  Panel Format                          (82c455/6/7 Only)
bit 0-1  Frame Rate Control
          0: No grey scale simulated for mono,
             8 colors simulated for color panels.
          1: 4 simulated colors for color panels only
             (64 colors displayed).
          2: (82c455/6) 64 grey levels simulated for mono. panels only.
             (82c457)   16 levels simulated for each color output.
                        4096 colors simulated.
          3: (82c457)   3 levels simulated for each color output.
                        27 colors simulated.
    2-3  Pulse Width Modulation
          0: No grey scales for mono or color systems.
          1: 4 colors supported by the color panels only
             (64 colors displayed).
          2: 16 grey levels supported by the mono panels only.
          3: 256 grey levels supported by the color single panels only.
             (655x0) Dither Enable.
               0: Disable Dither.
               1: Enable dither for 256 color modes.
               2: Enable dither for all modes.
    4-5  Clock Divide (CD).
          0: Shift Clock = Dot Clock
          1: Shift Clock = Dot Clock/2
          2: Shift Clock = Dot Clock/4
          3: (655x0) Shift Clock = Dot Clock/8.
      7  Shift Clock Mask.
         If set the Shift Clock stops outside the Display Enable interval.
    6-7  (655x0)  VAM/FRC Control
           0: bit 2-3 determine the dither:
               0: 6 bpp VAM (dither bits 0-1).
               1: 4 bpp VAM (dither bits 0-1).
               2: 2 bpp VAM (dither bits 2-3).
               3: 1 bpp VAM (dither bits 4-5).
           1: 3 Bits/Pixel VAM (dither bits 1-2).
              Use with bit 2-3=0 or 1 for mono panels,
              Use with bit 2-3=0 for color panels.
           2: (65530) 2-Frame FRC
              3 level grey scale simulation without dither or
              9 level grey scale simulation with dither.
           3: (65530) 3 Bits/Pixel VAM + 2-Frame FRC.
              15-level grey scale simulation without dithering and
              56 level grey scale simulation with dithering.