8514.txt

比较详尽的VGA端口寄存器的文档

Note: In the 8514/A this register is Writeonly,
      In the Chips&Tech 82c480 it is Read/Write.

52E8h W(R/W):  Extended Configuration Register (EC0)           (CT82c480 only)
bit  0-15  Reserved.

56E8h W(R/W):  Extended Configuration Register (EC1)           (CT82c480 only)
bit  0-15  Reserved.

5AE8h W(R/W):  Extended Configuration Register (EC2)           (CT82c480 only)
bit   0-2  Reserved(1)
      3-4  ROMBASE. Latched on reset from P4D3-4.
           Determines start address of ROM:
                    8K ROM         32K ROM
                  MC     ISA      MC     ISA       MC =Micro Channel
             0  0C8000  C6000   0D0000  D0000
             1  0D8000  D8000   0D8000  D8000
             2  0C0000  C0000   0C0000  C0000
             3  0C6000  C8000   0C8000  C8000
        5  ROMSIZE. Latched on reset from P4D5.
           If set the ROM is 8K, if clear the ROM is 32K.
        6  ROMPAGING. Latched from P4D6 on reset.
           If set the ROMPG pins are outputs, if clear they are inputs.
        7  8 Bit planes (8BP).
      8-9  BANKS. Number of VRAM banks.
            0=1  bank, 1=2 banks, 2=3 banks, 3=4 banks.
       10  If set 256Kx4 VRAMs are used, if clear 64Kx4 VRAMs.
           Sampled from MA8 on reset.
       11  5-Pixel Nuggets (5PN). Latched from WE4/ on reset.
           Determines whether there are 4 or 5 pixels to a nugget.
       12  Reserved(0)
       13  8-bit DAC Control (8BITDAC). If set the RAMDAC is 8bit rather than
           6bit. On reset the 8BITDAC pin is sampled, then the pin turns into
           an output driven by this bit. This can be used to switch a DAC with
           6/8bit ability like an IMSG178 or BT478 between 6 and 8 bits.
    14-15  Reserved(0)

5EE8h W(R/W):  Extended Configuration Register (EC3)           (CT82c480 only)
bit   0-3  Selects which registers will be read from BEE8h.
        4  Alternate High Register Select (AHRS). If set writes to video
           timing registers will go to the Alternate-High register set.
        5  Alternate Low Register Select (ALRS). If set writes to video timing
           registers will go to the Alternate-Low register set.
        6  Alternate High Register Enable (AHRE). If set enables the Alternate
           High-resolution video timing register set.
        7  Alternate Low Register Enable (ALRE). If set enables the Alternate
           Low-resolution video timing register set.
     8-10  Clock Select 0-2 (CLKSEL0-2). The CT82c480 maintains 3 different
           clock select register sets. On set each for Alternate High,
           Alternate Low and normal video.
       11  Reserved(0)
       12  OVERRIDE. If set the normal video register set is used.
           If clear the AHRE and ALRE determines the video register set used.
           This bit is reset on any write to the ADVFUNC_CTRL register (4AE8h)
    13-15  Reserved(0)
Note: Writes to this register should be 8-bit.

82E8h W(R/W):  Current Y Position Register (CUR_Y)
bit  0-11  Y Position. Y co-ordinate of current position in pixels.
    12-15  Reserved(0)

86E8h W(R/W):  Current X Position Register (CUR_X)
bit  0-11  X Position. X co-ordinate of current position in pixels.
    12-15  Reserved(0).
Note: In 5PN mode bits 11, 1 and 0 are remainder bits, bits 2-10 are the
      current X position modulo 5.

8AE8h W(R/W):  Destination Y Position & Axial Step Constant Register
               (DESTY_AXSTP)
bit  0-11  During BITBLT operations this is the Y co-ordinate of the
           destination in pixels. During Line Drawing, this is the Bresenham
           constant 2*dminor. (dminor is the length of the line projected
           onto the minor or dependent axis).
       12  AXSTPSIGN. Sign bit for Axial Step Constant.
           Should be 0 during BITBLT operations.
    13-15  Reserved(0)
Note: In the original IBM 8514/A this register is Write only. In the CT82c480
      it is read/writable

8EE8h W(R/W):  Destination X Position & Diagonal Step Constant Register
               (DESTX_DISTP)
bit  0-11  During BITBLT operations this is the X co-ordinate of the
           destination in pixels.
           During Line Drawing this is the Bresenham constant 2*dminor-
           2*dmajor. (dminor is the length of the line projected onto
           the minor or dependent axis, dmajor is the length of the
           line projected onto the major or independent axis)
       12  DGSTPSIGN. Sign bit for Diagonal Step Constant
           (Should be set to 0 for BITBLT operations).
    13-15  Reserved(0)
Note: In the original IBM 8514/A this register is Write only. In the CT82c480
      it is read/writable

92E8h W(R/W):  Error Term Register (ERR_TERM).
bit  0-12  Initial Error Term. This register is programmed to the Bresenham
           initial error term before a line drawing command is issued.
    13-15  Reserved. These bits are read/writable but have no function.

96E8h W(R/W):  Major Axis Pixel Count & Rectangle Width Register
               (MAJ_AXIS_PCNT)
bit  0-10  For BITBLT and rectangle commands this is the width of the area.
           For Line Drawing this is the Bresenham constant dmajor.
           Must be positive.
    11-15  Reserved(0)
Note: In the original IBM 8514/A this register is Write only.
      In the CT82c480 it is read/writable

9AE8h W(R):  Graphics Processor Status Register (GP_STAT)
bit   0-7  Queue State.
             00h = 8 words available - queue is empty
             01h = 7 words available
             03h = 6 words available
             07h = 5 words available
             0Fh = 4 words available
             1Fh = 3 words available
             3Fh = 2 words available
             7Fh = 1 word available
             FFh = 0 words available - queue is full
        8  DATARDY. If set data is ready to be read from
           the PIX_TRANS register (E2E8h).
        9  Graphics Processor Busy (GPBUSY)
           If set the Graphics Processor is busy.
    10-15  Reserved(0)

9AE8h W(W):  Command Register (CMD)
bit     0  WRTDATA. If set VRAM write operations are enabled. If clear
           operations execute normally but no writes to memory is performed.
        1  PLANAR defines the orientation of the display bitmap.
             0=Through plane mode, 1=Across plane mode.
        2  If set the last pixel of a line command (CMD_LINE, SSV or LINEAF)
           is not drawn. This is used for mixes such as XOR where drawing the
           same pixel twice would give the wrong color.
           For rectangle commands the effect is different depending on the
           INC_X and INC_Y fields:
              CMD_RECT
                 If INC_X is set then the rightmost column is not drawn,
                 if clear the leftmost column is not drawn.
              CMD_RECTV1
                 If INC_Y is set the bottom row is not drawn,
                 if clear the top row is not drawn.
              CMD_RECTV2
                 No effect
              CMD_BITBLT
                 If INC_X set the rightmost column is not drawn,
                 if clear the leftmost column is not drawn.
        3  LINETYPE.
             0: Bresenham line drawing
                  CMD_LINE draws a line using the Bresenham algorithm as
                  specified in the DESTY_AXSTP (8AE8h), DESTX_DIASTP (8EE8h),
                  ERR_TERM (92E8h) and MAJ_AXIS_PCNT (96E8h) registers
             1: Vector line draws.
                  CMD_NOP allows drawing of Short Stroke Vectors (SSVs) by
                  writing to the Short Stroke register (9EE8h).
                  CMD_LINE draws a vector of length MAJ_AXIS_PCNT (96E8h)
                  in the direction specified by LINEDIR (bits 5-7).
        4  DRAW. If clear the current position is moved, but no pixels
           are modified. This bit should be set when attempting read or
           write of bitmap data.
      5-7  LINEDIR. When a line draw command (CMD_LINE) with LINETYPE=1
           is issued, these bits define the direction of the line
           counter clockwise relative to the positive X-axis.
             0 = 000 degrees
             1 = 045 degrees
             2 = 090 degrees
             3 = 135 degrees
             4 = 180 degrees
             5 = 225 degrees
             6 = 270 degrees
             7 = 315 degrees
        5  INC_X. This bit together with INC_Y determines which quadrant
           the slope of a line lies within. They also determine the
           orientation of rectangle draw commands.
           If set lines are drawn in the positive X direction (left to right).
        6  YMAJAXIS. For Bresenham line drawing commands this bit determines
           which axis is the independent or major axis. INC_X and INC_Y
           determines which quadrant the slope falls within. This bit further
           defines the slope to within an octant.
           If set Y is the major (independent) axis.
        7  INC_Y. This bit together with INC_X determines which quadrant
           the slope of a line lies within. They also determine the
           orientation of rectangle draw commands.
           If set lines are drawn in the positive Y direction (down).
        8  (Pixel Data Enable) PCDATA.
           If set the drawing engine waits for read/write of the PIX_TRANS
           register (E2E8h) for each pixel during a draw operation.
        9  16BIT. If set the PIX_TRANS register (E2E8h) is processed
           internally as two bytes in the order specified by BYTSEQ.
           If clear all accesses are 8bit.
    10-11  Reserved(0)
       12  Byte Sequence (BYTSEQ). Affects both reads and writes of
           SHORT_STROKE (9EE8h) and PIX_TRANS (E2E8h) when 16bit=1.
           If set take low byte first, if clear take high byte first.
    13-15  Draw Command:
            0 = CMD_NOP.    (Should be used for Short Stroke Vectors).
            1 = CMD_LINE
            2 = CMD_RECT    (Fill rectangle in X direction)
            3 = CMD_RECTV1  (Fill rectangle in Y direction)
            4 = CMD_RECTV2  (Fast filled Y direction rectangle)
            5 = CMD_LINEAF  (Outline)
            6 = CMD_BITBLT  (Copy rectangle)
            7 = illegal

9EE8h W(R/W):  Short Stroke Vector Transfer Register (SHORT_STROKE)
bit   0-3  Length of vector projected onto the major axis.
           This is also the number of pixels drawn.
        4  Must be set for pixels to be written.
      5-7  VECDIR. The angle measured counter-clockwise from horizontal
           right) at which the line is drawn,
             0 = 000 degrees
             1 = 045 degrees
             2 = 090 degrees
             3 = 135 degrees
             4 = 180 degrees
             5 = 225 degrees
             6 = 270 degrees
             7 = 315 degrees
     8-15  The lower 8 bits are duplicated in the upper 8 bits so two
           short stroke vectors can be drawn with one command.
Note: The upper byte must be written for the SSV command to be executed.
      Thus if a byte is written to 9EE8h another byte must be written to