Colours on a Microbee

[Under4Mhz]

Thanks for the information. Since I'm using sdcc,I updated it to use C:

Code:

enum {
    crtStatusVSync = 5,                // Video is in vsync
    crtStatusLightPen,                 // Keyboard hit
    crtStatusUpdateReady,              // Wrote to reg 31
};

#define VDU_VSYNC_MASK ( 1 << crtStatusVSync )

static volatile __sfr __at 0x0C CrtRegPort;
static volatile __sfr __at 0x0D CrtDataPort;
static volatile __sfr __at 0x08 VduBankPort;

// from the R6545 crt display controller manual
enum {

    crtHorizontalTotalChars = 0,
    crtHorizontalDisplayedChars = 1,
    crtHorizontalSyncPosition = 2,

    crtHorizontalVerticalSyncWidths = 3,

    crtVerticalTotalRows = 4,
    crtVerticalTotalLineAdjust = 5,
    crtVerticalDisplayedRows = 6,
    crtVerticalSyncPosition = 7,
    crtModeControl = 8,
    crtRowScanLines = 9,

    crtCursorPositionHigh = 14,
    crtCursorPositionLow,
};

///< Setup crt to 64x16 tiles and hide the cursor
void vdu_crt_setup() {

    // Cursor off screen
    CrtRegPort = crtCursorPositionHigh;
    CrtDataPort = 0xff;
    CrtRegPort = crtCursorPositionLow;
    CrtDataPort = 0xff;

    CrtRegPort = crtHorizontalDisplayedChars; // Columns on screen
    CrtDataPort = 64;
    CrtRegPort = crtVerticalDisplayedRows;    // Rows on screen
    CrtDataPort = 16;
    CrtRegPort = crtRowScanLines;             // Rows per character - cuts of the bottom of tiles
    CrtDataPort = 15;                         // Rows - 1
}

///< Switch in vdu PCG or colour data at 0xF8000
void vdu_bank( bool colour ) __fastcall {

    VduBankPort = colour ? 0x47 : 0x07;
}

///< Wait for full vblank cycle, so 1/50th of a second has passed (for timing)
void vdu_wait() {

    #define VDU_STATUS_PORT 0x0C
    #define VDU_VSYNC_BIT 5

    __asm

crt_poll:
        in      a,(#VDU_STATUS_PORT)
        bit    #VDU_VSYNC_BIT,a
        jp      z, crt_poll

crt_poll_end:
        in      a,(#VDU_STATUS_PORT)
        bit    #VDU_VSYNC_BIT,a
        jp      nz, crt_poll_end

    __endasm;

}