Augusto Baffa's pages

// Videx Videoterm Card Emulator
// by Augusto Baffa feb 2024
// 
// Based on Apple II Simulator
// by Peter Koch, May 6, 1993 

int videx_slot = 3;
bool card_videx = true;
bool card_videx_mem_on = false;
bool card_videx_80col = false;

class VidexCard {


    /*
    //notes:

    // To turn on/off 80 columns mode:
    // Write at 0xC058 or 0xC059 
    //        card_videx_80col = (addr == 0xc059);
    //
    // To Control the card:
    //
    // IOSEL (0xC300-C3FFF - slot 3)
    // Read 
    //        r = videxcard.getRomIoSel(addr & 0x1FF);
    //        card_videx_mem_on = true;
    // Write
    //        card_videx_mem_on = true;
    //
    // DEVSEL (0xC0B0-C0BF - slot 3)
    // Read
    //        r = videxcard.getC0SLOTX(addr);
    //        
    // Write
    //        videxcard.putC0SLOTX(addr, val);
    //
    // IOSTB  (0xC800-CFFF)
    // Read
    //        if (((addr >> 9) & 0b11) == 0b11) card_videx_mem_on = false;
    //
    //        if (card_videx_mem_on && addr >= 0xC800 && addr <= 0xCDFF)
    //            r = videxcard.getSLOTC8XX(addr & 0x7ff);
    //
    // Write
    //        if (((addr >> 9) & 0b11) == 0b11) card_videx_mem_on = false;
    //
    //        if (card_videx_mem_on && addr >= 0xC800 && addr <= 0xCDFF) 
    //            videxcard.putSLOTC8XX(addr - 0xC800, val);   
    //
    // To Render:
    //
    //
    //for (int y = 0; y < 25; y++) {
    //    for (int x = 0; x < 80; x++) {
    //
    //        int vkeycode = videxcard.getCSLOTXX(x, y); // get ascii code from memory
    //        bool vinverse = videxcard.isCursorPosition(x, y); // check cursor position to inverse
    //
    //        for (int i = 0; i < 9; i++) {
    //
    //            int video_bits = videxcard.getVideoBits(vkeycode, i); // get bits for the current char/scanline
    //
    //            if (vinverse)
    //                display_bit_80col(renderer, x, y, ~video_bits, i); // render char/scanline
    //            else
    //                display_bit_80col(renderer, x, y, video_bits, i); // render char/scanline
    //
    //        }
    //    }
    //}
    */

private:
    uint8_t videx_rom[0x400]; // 0x0400 at C800-CBFF 
    uint8_t videx_chars[0xfff]; // 0x0-0x7ff rom 1 | 0x800-0xfff rom2 character rom (12x8) Matrix)  
    uint8_t videx_vram[2048]; // 0x0800 at CC00-CDFF in 4 banks of 0x1FF


    // internal variables 
    int videx_bankSLOT, videx_regvalSLOT;  // active memory bank, selected register 
    unsigned char videx_regSLOT[17];// registers of the CRT-controller 
    //int videx_oldcursorSLOT;      // old cursor position 
    //int videx_upperSLOT, videx_lowerSLOT;  // cursor size 
    //*******************************************************
    // Registers
    //    register r/w     normal value    Name              
    //    00:      w       7B              Horiz. total      
    //    01:      w       50              Horiz. displayed  
    //    02:      w       62              Horiz. sync pos   
    //    03:      w       29              Horiz. sync width 
    //    04:      w       1B              Vert. total       
    //    05:      w       08              Vert. adjust      
    //    06:      w       18              Vert. displayed   
    //    07:      w       19              Vert. sync pos    
    //    08:      w       00              Interlaced        
    //    09:      w       08              Max. scan line    
    //    10:0A    w       C0              Cursor upper      
    //    11:0B    w       08              Cursor lower      
    //    12:0C    w       00              Startpos Hi       
    //    13:0D    w       00              Startpos Lo       
    //    14:0E    r/w     00              Cursor Hi         
    //    15:0F    r/w     00              Cursor Lo         
    //    16:10    r       00              Lightpen Hi       
    //    17:11    r       00              Lightpen Lo       
    //
    // The registers are addressed as follows:
    //    To write                  To read
    //    LDA #$          LDA #$         
    //    STA $C0B0                 STA $C0B0                
    //    LDA #$             LDA $C0B1                
    //    STA $C0B1                                          
    //*******************************************************
    
public:
    int getC0SLOTX(int adr)// 0x0400 at C800-CBFF 
    {
        int value = 0x00;

        //define current memory bank
        videx_bankSLOT = (adr & 0x000c) >> 2;

        if (adr & 0x0001)
            // get current register value
            value = videx_regSLOT[videx_regvalSLOT];
        else 
            // define current register
            videx_regvalSLOT = value;

        return value;
    }


    void putC0SLOTX(int adr, int value)// 0x0400 at C800-CBFF 
    {

        //define current memory bank
        videx_bankSLOT = (adr & 0x000c) >> 2;

        if (adr & 0x0001)
        {
            // set current register value
            videx_regSLOT[videx_regvalSLOT] = value;

            /*
            //10:0A Cursor upper //11:0B Cursor lower
            if ((videx_regvalSLOT == 10) || (videx_regvalSLOT == 11)) 
                modifySLOT();

            //14:0E Cursor Hi //15:0F Cursor Lo
            if ((videx_regvalSLOT == 14) || (videx_regvalSLOT == 15)) 
                cursorSLOT();

            //13:0D Startpos Lo
            if (videx_regvalSLOT == 13) 
                redrawSLOT();
            
            //12:0C Startpos Hi
            */
            
        }
        else
 // define current register
...