Editing FNX6809 GraphicsVTIOCalls (section)

=== SS.DScrn ===
Display Screen Settings

Set MCR to display text or graphics or both

 Entry: R$X = Vicky_MCR Low Byte
        R$Y = Vicky_MCR High Byte

 Exit:  Nothing. This just sets the register and updates driver variables

VICKY MASTER CONTROL REGISTER to enable graphics and capabilities
 | 7 |   6   |    5   |   4  |    3   |   2   |   1   |   0  |
 | X | GAMMA | SPRITE | TILE | BITMAP | GRAPH | OVRLY | TEXT |
 |   -----   | FON_SET|FON_OV| MON_SLP| DBL_Y | DBL_X | CLK70|
 $FFC0 MASTER_CTRL_REG_L, MASTER_CTRL_REG_H
 
 ********************************************************************
 * vtio graphics constants (in f256.d)
 ********************************************************************
 * Constants used in SS.DScrn to set the display screen type

 FX_GAM             equ       %01000000              Gamma Correction On
 FX_SPR             equ       %00100000              Sprites On
 FX_TIL             equ       %00010000              Tile Maps On
 FX_BM              equ       %00001000              Bitmaps On
 FX_GRF             equ       %00000100              Graphics Mode On
 FX_OVR             equ       %00000010              Overlay Text on Graphics
 FX_TXT             equ       %00000001              Text Mode On
 FT_FSET            equ       %00100000              Font Set 1 On (0=Font Set 0)
 FT_FOVR            equ       %00010000              FG and BG colors displayed when overlay text 0=transparent
 FT_MON             equ       %00001000              Turn off monitor sync and sleep monitor
 FT_DBX             equ       %00000100              Double-wide text mode characters
 FT_DBY             equ       %00000010              Double-high text mode characters
 FT_CLK70           equ       %00000001              70 Hz screen (640x400 txt,320x200 grf)
 FX_OMIT            equ       %11111111              Setting for SS.DScrn don't change first byte in MCR
 FT_OMIT            equ       %11111111              Setting for SS.DScrn don't change second byte in MCR