diff --git a/src/include/86box/vid_cga.h b/src/include/86box/vid_cga.h
index a503d12ba..2a36eeade 100644
--- a/src/include/86box/vid_cga.h
+++ b/src/include/86box/vid_cga.h
@@ -15,16 +15,65 @@
  *
  *          Copyright 2008-2018 Sarah Walker.
  *          Copyright 2016-2018 Miran Grca.
+ *          Copyright 2025 starfrost (refactoring)
  */
 
 #ifndef VIDEO_CGA_H
 #define VIDEO_CGA_H
 
+// Mode flags for the CGA.
+// Set by writing to 3D8
+typedef enum cga_mode_flags_e
+{
+    CGA_MODE_FLAG_HIGHRES = 1 << 0,                     // 80-column text mode
+    CGA_MODE_FLAG_GRAPHICS = 1 << 1,                    // Graphics mode
+    CGA_MODE_FLAG_BW = 1 << 2,                          // Black and white 
+    CGA_MODE_FLAG_VIDEO_ENABLE = 1 << 3,                // 0 = no video (as if the video was 0)
+    CGA_MODE_FLAG_HIGHRES_GRAPHICS = 1 << 4,            // 640*200 mode. Corrupts text mode if CGA_MODE_FLAG_GRAPHICS not set.
+    CGA_MODE_FLAG_BLINK = 1 << 5,                       // If this is set, bit 5 of textmode characters blinks. Otherwise it is a high-intensity bg mode.
+} cga_mode_flags;
+
+// Motorola MC6845 CRTC registers
+typedef enum cga_crtc_registers_e
+{
+    CGA_CRTC_HTOTAL = 0x0,                              // Horizontal total (total number of characters incl. hsync)
+    CGA_CRTC_HDISP = 0x1,                               // Horizontal display 
+    CGA_CRTC_HSYNC_POS = 0x2,                           // Horizontal position of horizontal ysnc
+    CGA_CRTC_HSYNC_WIDTH = 0x3,                         // Width of horizontal sync
+    CGA_CRTC_VTOTAL = 0x4,                              // Vertical total (total number of scanlines incl. vsync)
+    CGA_CRTC_VTOTAL_ADJUST = 0x5,                       // Vertical total adjust value
+    CGA_CRTC_VDISP = 0x6,                               // Vertical display (total number of displayed scanline)
+    CGA_CRTC_VSYNC = 0x7,                               // Vertical sync scanline number
+    CGA_CRTC_INTERLACE = 0x8,                           // Interlacing mode
+    CGA_CRTC_MAX_SCANLINE_ADDR = 0x9,                   // Maximum scanline address
+    CGA_CRTC_CURSOR_START = 0xA,                        // Cursor start scanline
+    CGA_CRTC_CURSOR_END = 0xB,                          // Cursor end scanline
+    CGA_CRTC_START_ADDR_HIGH = 0xC,                     // Screen start address high 8 bits
+    CGA_CRTC_START_ADDR_LOW = 0xD,                      // Screen start address low 8 bits
+    CGA_CRTC_CURSOR_ADDR_HIGH = 0xE,                    // Cursor address high 8 bits
+    CGA_CRTC_CURSOR_ADDR_LOW = 0xF,                     // Cursor address low 8 bits
+    CGA_CRTC_LIGHT_PEN_ADDR_HIGH = 0x10,                // Light pen address high 8 bits (not currently supported)
+    CGA_CRTC_LIGHT_PEN_ADDR_LOW = 0x11,                 // Light pen address low 8 bits (not currently supported)
+} cga_crtc_registers;
+
+typedef enum cga_registers_e
+{
+    CGA_REGISTER_CRTC_INDEX = 0x3D4,
+    CGA_REGISTER_CRTC_DATA = 0x3D5,
+    CGA_REGISTER_MODE_CONTROL = 0x3D8,
+    CGA_REGISTER_COLOR_SELECT = 0x3D9,
+    CGA_REGISTER_STATUS = 0x3DA,
+    CGA_REGISTER_CLEAR_LIGHT_PEN_LATCH = 0x3DB,
+    CGA_REGISTER_SET_LIGHT_PEN_LATCH = 0x3DC,
+} cga_registers;
+
+#define CGA_NUM_CRTC_REGS   32
+
 typedef struct cga_t {
     mem_mapping_t mapping;
 
     int     crtcreg;
-    uint8_t crtc[32];
+    uint8_t crtc[CGA_NUM_CRTC_REGS];
 
     uint8_t cgastat;
 
@@ -40,7 +89,6 @@ typedef struct cga_t {
     int      vc;
     int      cgadispon;
     int      con;
-    int      coff;
     int      cursoron;
     int      cgablink;
     int      vsynctime;
diff --git a/src/include/86box/vid_hercules.h b/src/include/86box/vid_hercules.h
index c58a50aa3..a468dce55 100644
--- a/src/include/86box/vid_hercules.h
+++ b/src/include/86box/vid_hercules.h
@@ -47,7 +47,6 @@ typedef struct {
     uint16_t ma;
     uint16_t maback;
     int      con;
-    int      coff;
     int      cursoron;
     int      dispon;
     int      blink;
diff --git a/src/include/86box/vid_mda.h b/src/include/86box/vid_mda.h
index d13c45a28..eeea5a093 100644
--- a/src/include/86box/vid_mda.h
+++ b/src/include/86box/vid_mda.h
@@ -29,7 +29,6 @@ typedef struct mda_t {
     uint16_t ma;
     uint16_t maback;
     int      con;
-    int      coff;
     int      cursoron;
     int      dispon;
     int      blink;
diff --git a/src/include/86box/vid_pgc.h b/src/include/86box/vid_pgc.h
index 35e2d9e42..43226a0f5 100644
--- a/src/include/86box/vid_pgc.h
+++ b/src/include/86box/vid_pgc.h
@@ -116,7 +116,6 @@ typedef struct pgc {
     int      vc;
     int      cgadispon;
     int      con;
-    int      coff;
     int      cursoron;
     int      cgablink;
     int      vsynctime;
diff --git a/src/machine/m_amstrad.c b/src/machine/m_amstrad.c
index 814d95ffd..57e8367ff 100644
--- a/src/machine/m_amstrad.c
+++ b/src/machine/m_amstrad.c
@@ -117,7 +117,6 @@ typedef struct amsvid_t {
     int        vc;
     int        cgadispon;
     int        con;
-    int        coff;
     int        cursoron;
     int        cgablink;
     int        vsynctime;
@@ -515,7 +514,6 @@ vid_poll_1512(void *priv)
         }
         if (vid->sc == (vid->crtc[11] & 31)) {
             vid->con  = 0;
-            vid->coff = 1;
         }
         if (vid->vadj) {
             vid->sc++;
@@ -1319,7 +1317,6 @@ lcdm_poll(amsvid_t *vid)
         }
         if (mda->sc == (mda->crtc[11] & 31) || ((mda->crtc[8] & 3) == 3 && mda->sc == ((mda->crtc[11] & 31) >> 1))) {
             mda->con  = 0;
-            mda->coff = 1;
         }
         if (mda->vadj) {
             mda->sc++;
@@ -1483,7 +1480,6 @@ lcdc_poll(amsvid_t *vid)
         }
         if (cga->sc == (cga->crtc[11] & 31) || ((cga->crtc[8] & 3) == 3 && cga->sc == ((cga->crtc[11] & 31) >> 1))) {
             cga->con  = 0;
-            cga->coff = 1;
         }
         if ((cga->crtc[8] & 3) == 3 && cga->sc == (cga->crtc[9] >> 1))
             cga->maback = cga->ma;
diff --git a/src/machine/m_pcjr.c b/src/machine/m_pcjr.c
index cb69bd9e5..f2da2e2b5 100644
--- a/src/machine/m_pcjr.c
+++ b/src/machine/m_pcjr.c
@@ -82,7 +82,6 @@ typedef struct pcjr_t {
     int           vc;
     int           dispon;
     int           con;
-    int           coff;
     int           cursoron;
     int           blink;
     int           vsynctime;
@@ -1167,7 +1166,6 @@ vid_poll(void *priv)
         }
         if (pcjr->sc == (pcjr->crtc[11] & 31) || ((pcjr->crtc[8] & 3) == 3 && pcjr->sc == ((pcjr->crtc[11] & 31) >> 1))) {
             pcjr->con  = 0;
-            pcjr->coff = 1;
         }
         if (pcjr->vadj) {
             pcjr->sc++;
diff --git a/src/machine/m_tandy.c b/src/machine/m_tandy.c
index 7072c5e78..4d0768378 100644
--- a/src/machine/m_tandy.c
+++ b/src/machine/m_tandy.c
@@ -92,7 +92,6 @@ typedef struct t1kvid_t {
     int      vc;
     int      dispon;
     int      con;
-    int      coff;
     int      cursoron;
     int      blink;
     int      fullchange;
@@ -1212,7 +1211,6 @@ vid_poll(void *priv)
         }
         if (vid->sc == (vid->crtc[11] & 31) || ((vid->crtc[8] & 3) == 3 && vid->sc == ((vid->crtc[11] & 31) >> 1))) {
             vid->con  = 0;
-            vid->coff = 1;
         }
         if (vid->vadj) {
             vid->sc++;
diff --git a/src/video/vid_cga.c b/src/video/vid_cga.c
index a24162019..4a9a032c5 100644
--- a/src/video/vid_cga.c
+++ b/src/video/vid_cga.c
@@ -16,7 +16,7 @@
  *
  *          Copyright 2008-2019 Sarah Walker.
  *          Copyright 2016-2019 Miran Grca.
- *          Copyright 2023 W. M. Martinez
+ *          Copyright 2023 W. M. Martine
  */
 #include <stdio.h>
 #include <stdint.h>
@@ -73,10 +73,10 @@ void cga_recalctimings(cga_t *cga);
 static void
 cga_update_latch(cga_t *cga)
 {
-    uint32_t lp_latch = cga->displine * cga->crtc[1];
+    uint32_t lp_latch = cga->displine * cga->crtc[CGA_CRTC_HDISP];
 
     cga->crtc[0x10] = (lp_latch >> 8) & 0x3f;
-    cga->crtc[0x11] = lp_latch & 0xff;
+    cga->crtc[CGA_CRTC_LIGHT_PEN_ADDR_LOW] = lp_latch & 0xff;
 }
 
 void
@@ -89,20 +89,22 @@ cga_out(uint16_t addr, uint8_t val, void *priv)
         addr = (addr & 0xff9) | 0x004;
 
     switch (addr) {
-        case 0x3D4:
+        case CGA_REGISTER_CRTC_INDEX:
             cga->crtcreg = val & 31;
             return;
-        case 0x3D5:
+        case CGA_REGISTER_CRTC_DATA:
             old                     = cga->crtc[cga->crtcreg];
             cga->crtc[cga->crtcreg] = val & crtcmask[cga->crtcreg];
             if (old != val) {
+                // Recalc the timings if we are writing any invalid CRTC register or a valid CRTC register 
+                // except the CURSOR and LIGHT PEN registers
                 if ((cga->crtcreg < 0xe) || (cga->crtcreg > 0x11)) {
                     cga->fullchange = changeframecount;
                     cga_recalctimings(cga);
                 }
             }
             return;
-        case 0x3D8:
+        case CGA_REGISTER_MODE_CONTROL:
             old          = cga->cgamode;
             cga->cgamode = val;
 
@@ -113,18 +115,18 @@ cga_out(uint16_t addr, uint8_t val, void *priv)
                 cga_recalctimings(cga);
             }
             return;
-        case 0x3D9:
+        case CGA_REGISTER_COLOR_SELECT:
             old         = cga->cgacol;
             cga->cgacol = val;
             if (old ^ val)
                 cga_recalctimings(cga);
             return;
 
-        case 0x3DB:
+        case CGA_REGISTER_CLEAR_LIGHT_PEN_LATCH:
             if (cga->lp_strobe == 1)
                 cga->lp_strobe = 0;
             return;
-        case 0x3DC:
+        case CGA_REGISTER_SET_LIGHT_PEN_LATCH:
             if (cga->lp_strobe == 0) {
                 cga->lp_strobe = 1;
                 cga_update_latch(cga);
@@ -146,21 +148,20 @@ cga_in(uint16_t addr, void *priv)
         addr = (addr & 0xff9) | 0x004;
 
     switch (addr) {
-        case 0x3D4:
+        case CGA_REGISTER_CRTC_INDEX:
             ret = cga->crtcreg;
             break;
-        case 0x3D5:
+        case CGA_REGISTER_CRTC_DATA:
             ret = cga->crtc[cga->crtcreg];
             break;
-        case 0x3DA:
+        case CGA_REGISTER_STATUS:
             ret = cga->cgastat;
             break;
-
-        case 0x3DB:
+        case CGA_REGISTER_CLEAR_LIGHT_PEN_LATCH:
             if (cga->lp_strobe == 1)
                 cga->lp_strobe = 0;
             break;
-        case 0x3DC:
+        case CGA_REGISTER_SET_LIGHT_PEN_LATCH:
             if (cga->lp_strobe == 0) {
                 cga->lp_strobe = 1;
                 cga_update_latch(cga);
@@ -235,12 +236,12 @@ cga_recalctimings(cga_t *cga)
     double _dispontime;
     double _dispofftime;
 
-    if (cga->cgamode & 1) {
-        disptime    = (double) (cga->crtc[0] + 1);
-        _dispontime = (double) cga->crtc[1];
+    if (cga->cgamode & CGA_MODE_FLAG_HIGHRES) {
+        disptime    = (double) (cga->crtc[CGA_CRTC_HTOTAL] + 1);
+        _dispontime = (double) cga->crtc[CGA_CRTC_HDISP];
     } else {
-        disptime    = (double) ((cga->crtc[0] + 1) << 1);
-        _dispontime = (double) (cga->crtc[1] << 1);
+        disptime    = (double) ((cga->crtc[CGA_CRTC_HTOTAL] + 1) << 1);
+        _dispontime = (double) (cga->crtc[CGA_CRTC_HDISP] << 1);
     }
     _dispofftime     = disptime - _dispontime;
     _dispontime      = _dispontime * CGACONST;
@@ -252,7 +253,7 @@ cga_recalctimings(cga_t *cga)
 static void
 cga_render(cga_t *cga, int line)
 {
-    uint16_t ca  = (cga->crtc[15] | (cga->crtc[14] << 8)) & 0x3fff;
+    uint16_t ca  = (cga->crtc[CGA_CRTC_CURSOR_ADDR_LOW] | (cga->crtc[CGA_CRTC_CURSOR_ADDR_HIGH] << 8)) & 0x3fff;
     int      drawcursor;
     int      x;
     int      c;
@@ -262,33 +263,35 @@ cga_render(cga_t *cga, int line)
     int      cols[4];
     int      col;
 
-    if ((cga->cgamode & 0x12) == 0x12) {
+    int32_t  highres_graphics_flag = (CGA_MODE_FLAG_HIGHRES_GRAPHICS | CGA_MODE_FLAG_GRAPHICS);
+
+    if (((cga->cgamode & highres_graphics_flag) == highres_graphics_flag)) {
         for (c = 0; c < 8; ++c) {
             buffer32->line[line][c] = 0;
-            if (cga->cgamode & 1)
-                buffer32->line[line][c + (cga->crtc[1] << 3) + 8] = 0;
+            if (cga->cgamode & CGA_MODE_FLAG_HIGHRES)
+                buffer32->line[line][c + (cga->crtc[CGA_CRTC_HDISP] << 3) + 8] = 0;
             else
-                buffer32->line[line][c + (cga->crtc[1] << 4) + 8] = 0;
+                buffer32->line[line][c + (cga->crtc[CGA_CRTC_HDISP] << 4) + 8] = 0;
         }
     } else {
         for (c = 0; c < 8; ++c) {
             buffer32->line[line][c] = (cga->cgacol & 15) + 16;
-            if (cga->cgamode & 1)
-                buffer32->line[line][c + (cga->crtc[1] << 3) + 8] = (cga->cgacol & 15) + 16;
+            if (cga->cgamode & CGA_MODE_FLAG_HIGHRES)
+                buffer32->line[line][c + (cga->crtc[CGA_CRTC_HDISP] << 3) + 8] = (cga->cgacol & 15) + 16;
             else
-                buffer32->line[line][c + (cga->crtc[1] << 4) + 8] = (cga->cgacol & 15) + 16;
+                buffer32->line[line][c + (cga->crtc[CGA_CRTC_HDISP] << 4) + 8] = (cga->cgacol & 15) + 16;
         }
     }
-    if (cga->cgamode & 1) {
-        for (x = 0; x < cga->crtc[1]; x++) {
-            if (cga->cgamode & 8) {
+    if (cga->cgamode & CGA_MODE_FLAG_HIGHRES) {
+        for (x = 0; x < cga->crtc[CGA_CRTC_HDISP]; x++) {
+            if (cga->cgamode & CGA_MODE_FLAG_VIDEO_ENABLE) {
                 chr  = cga->charbuffer[x << 1];
                 attr = cga->charbuffer[(x << 1) + 1];
             } else
                 chr = attr = 0;
             drawcursor = ((cga->ma == ca) && cga->con && cga->cursoron);
             cols[1]    = (attr & 15) + 16;
-            if (cga->cgamode & 0x20) {
+            if (cga->cgamode & CGA_MODE_FLAG_BLINK) {
                 cols[0] = ((attr >> 4) & 7) + 16;
                 if ((cga->cgablink & 8) && (attr & 0x80) && !cga->drawcursor)
                     cols[1] = cols[0];
@@ -308,15 +311,15 @@ cga_render(cga_t *cga, int line)
             cga->ma++;
         }
     } else if (!(cga->cgamode & 2)) {
-        for (x = 0; x < cga->crtc[1]; x++) {
-            if (cga->cgamode & 8) {
+        for (x = 0; x < cga->crtc[CGA_CRTC_HDISP]; x++) {
+            if (cga->cgamode & CGA_MODE_FLAG_VIDEO_ENABLE) {
                 chr  = cga->vram[(cga->ma << 1) & 0x3fff];
                 attr = cga->vram[((cga->ma << 1) + 1) & 0x3fff];
             } else
                 chr = attr = 0;
             drawcursor = ((cga->ma == ca) && cga->con && cga->cursoron);
             cols[1]    = (attr & 15) + 16;
-            if (cga->cgamode & 0x20) {
+            if (cga->cgamode & CGA_MODE_FLAG_BLINK) {
                 cols[0] = ((attr >> 4) & 7) + 16;
                 if ((cga->cgablink & 8) && (attr & 0x80))
                     cols[1] = cols[0];
@@ -337,10 +340,10 @@ cga_render(cga_t *cga, int line)
                 }
             }
         }
-    } else if (!(cga->cgamode & 16)) {
+    } else if (!(cga->cgamode & CGA_MODE_FLAG_HIGHRES_GRAPHICS)) {
         cols[0] = (cga->cgacol & 15) | 16;
         col     = (cga->cgacol & 16) ? 24 : 16;
-        if (cga->cgamode & 4) {
+        if (cga->cgamode & CGA_MODE_FLAG_BW) {
             cols[1] = col | 3; /* Cyan */
             cols[2] = col | 4; /* Red */
             cols[3] = col | 7; /* White */
@@ -353,8 +356,8 @@ cga_render(cga_t *cga, int line)
             cols[2] = col | 4; /* Red */
             cols[3] = col | 6; /* Yellow */
         }
-        for (x = 0; x < cga->crtc[1]; x++) {
-            if (cga->cgamode & 8)
+        for (x = 0; x < cga->crtc[CGA_CRTC_HDISP]; x++) {
+            if (cga->cgamode & CGA_MODE_FLAG_VIDEO_ENABLE)
                 dat = (cga->vram[((cga->ma << 1) & 0x1fff) + ((cga->sc & 1) * 0x2000)] << 8) |
                       cga->vram[((cga->ma << 1) & 0x1fff) + ((cga->sc & 1) * 0x2000) + 1];
             else
@@ -370,8 +373,8 @@ cga_render(cga_t *cga, int line)
     } else {
         cols[0] = 0;
         cols[1] = (cga->cgacol & 15) + 16;
-        for (x = 0; x < cga->crtc[1]; x++) {
-            if (cga->cgamode & 8)
+        for (x = 0; x < cga->crtc[CGA_CRTC_HDISP]; x++) {
+            if (cga->cgamode & CGA_MODE_FLAG_VIDEO_ENABLE)
                 dat = (cga->vram[((cga->ma << 1) & 0x1fff) + ((cga->sc & 1) * 0x2000)] << 8) |
                       cga->vram[((cga->ma << 1) & 0x1fff) + ((cga->sc & 1) * 0x2000) + 1];
             else
@@ -388,12 +391,14 @@ cga_render(cga_t *cga, int line)
 static void
 cga_render_blank(cga_t *cga, int line)
 {
-    int col = ((cga->cgamode & 0x12) == 0x12) ? 0 : (cga->cgacol & 15) + 16;
+    int32_t  highres_graphics_flag = (CGA_MODE_FLAG_HIGHRES_GRAPHICS | CGA_MODE_FLAG_GRAPHICS);
 
-    if (cga->cgamode & 1)
-        hline(buffer32, 0, line, (cga->crtc[1] << 3) + 16, col);
+    int col = ((cga->cgamode & highres_graphics_flag) == highres_graphics_flag) ? 0 : (cga->cgacol & 15) + 16;
+
+    if (cga->cgamode & CGA_MODE_FLAG_HIGHRES)
+        hline(buffer32, 0, line, (cga->crtc[CGA_CRTC_HDISP] << 3) + 16, col);
     else
-        hline(buffer32, 0, line, (cga->crtc[1] << 4) + 16, col);
+        hline(buffer32, 0, line, (cga->crtc[CGA_CRTC_HDISP] << 4) + 16, col);
 }
 
 static void
@@ -401,14 +406,15 @@ cga_render_process(cga_t *cga, int line)
 {
     int      x;
     uint8_t  border;
+    int32_t  highres_graphics_flag = (CGA_MODE_FLAG_HIGHRES_GRAPHICS | CGA_MODE_FLAG_GRAPHICS);
 
-    if (cga->cgamode & 1)
-        x = (cga->crtc[1] << 3) + 16;
+    if (cga->cgamode & CGA_MODE_FLAG_HIGHRES)
+        x = (cga->crtc[CGA_CRTC_HDISP] << 3) + 16;
     else
-        x = (cga->crtc[1] << 4) + 16;
+        x = (cga->crtc[CGA_CRTC_HDISP] << 4) + 16;
 
     if (cga->composite) {
-        border = ((cga->cgamode & 0x12) == 0x12) ? 0 : (cga->cgacol & 15);
+        border = ((cga->cgamode & highres_graphics_flag) == highres_graphics_flag) ? 0 : (cga->cgacol & 15);
 
         Composite_Process(cga->cgamode, border, x >> 2, buffer32->line[line]);
     } else
@@ -524,7 +530,7 @@ cga_poll(void *priv)
         cga->cgastat |= 1;
         cga->linepos = 1;
         oldsc        = cga->sc;
-        if ((cga->crtc[8] & 3) == 3)
+        if ((cga->crtc[CGA_CRTC_INTERLACE] & 3) == 3)
             cga->sc = ((cga->sc << 1) + cga->oddeven) & 7;
         if (cga->cgadispon) {
             if (cga->displine < cga->firstline) {
@@ -573,7 +579,7 @@ cga_poll(void *priv)
         }
 
         cga->sc = oldsc;
-        if (cga->vc == cga->crtc[7] && !cga->sc)
+        if (cga->vc == cga->crtc[CGA_CRTC_VSYNC] && !cga->sc)
             cga->cgastat |= 8;
         cga->displine++;
         if (cga->displine >= 360)
@@ -586,12 +592,11 @@ cga_poll(void *priv)
             if (!cga->vsynctime)
                 cga->cgastat &= ~8;
         }
-        if (cga->sc == (cga->crtc[11] & 31) || ((cga->crtc[8] & 3) == 3 &&
-            cga->sc == ((cga->crtc[11] & 31) >> 1))) {
+        if (cga->sc == (cga->crtc[CGA_CRTC_CURSOR_END] & 31) || ((cga->crtc[CGA_CRTC_INTERLACE] & 3) == 3 &&
+            cga->sc == ((cga->crtc[CGA_CRTC_CURSOR_END] & 31) >> 1))) {
             cga->con  = 0;
-            cga->coff = 1;
         }
-        if ((cga->crtc[8] & 3) == 3 && cga->sc == (cga->crtc[9] >> 1))
+        if ((cga->crtc[CGA_CRTC_INTERLACE] & 3) == 3 && cga->sc == (cga->crtc[CGA_CRTC_MAX_SCANLINE_ADDR] >> 1))
             cga->maback = cga->ma;
         if (cga->vadj) {
             cga->sc++;
@@ -600,27 +605,27 @@ cga_poll(void *priv)
             cga->vadj--;
             if (!cga->vadj) {
                 cga->cgadispon = 1;
-                cga->ma = cga->maback = (cga->crtc[13] | (cga->crtc[12] << 8)) & 0x3fff;
+                cga->ma = cga->maback = (cga->crtc[CGA_CRTC_START_ADDR_LOW] | (cga->crtc[CGA_CRTC_START_ADDR_HIGH] << 8)) & 0x3fff;
                 cga->sc               = 0;
             }
-        } else if (cga->sc == cga->crtc[9]) {
+        } else if (cga->sc == cga->crtc[CGA_CRTC_MAX_SCANLINE_ADDR]) {
             cga->maback = cga->ma;
             cga->sc     = 0;
             oldvc       = cga->vc;
             cga->vc++;
             cga->vc &= 127;
 
-            if (cga->vc == cga->crtc[6])
+            if (cga->vc == cga->crtc[CGA_CRTC_VDISP])
                 cga->cgadispon = 0;
 
-            if (oldvc == cga->crtc[4]) {
+            if (oldvc == cga->crtc[CGA_CRTC_VTOTAL]) {
                 cga->vc   = 0;
-                cga->vadj = cga->crtc[5];
+                cga->vadj = cga->crtc[CGA_CRTC_VTOTAL_ADJUST];
                 if (!cga->vadj) {
                     cga->cgadispon = 1;
-                    cga->ma = cga->maback = (cga->crtc[13] | (cga->crtc[12] << 8)) & 0x3fff;
+                    cga->ma = cga->maback = (cga->crtc[CGA_CRTC_START_ADDR_LOW] | (cga->crtc[CGA_CRTC_START_ADDR_HIGH] << 8)) & 0x3fff;
                 }
-                switch (cga->crtc[10] & 0x60) {
+                switch (cga->crtc[CGA_CRTC_CURSOR_START] & 0x60) {
                     case 0x20:
                         cga->cursoron = 0;
                         break;
@@ -633,15 +638,15 @@ cga_poll(void *priv)
                 }
             }
 
-            if (cga->vc == cga->crtc[7]) {
+            if (cga->vc == cga->crtc[CGA_CRTC_VSYNC]) {
                 cga->cgadispon = 0;
                 cga->displine  = 0;
                 cga->vsynctime = 16;
-                if (cga->crtc[7]) {
-                    if (cga->cgamode & 1)
-                        x = (cga->crtc[1] << 3) + 16;
+                if (cga->crtc[CGA_CRTC_VSYNC]) {
+                    if (cga->cgamode & CGA_MODE_FLAG_HIGHRES)
+                        x = (cga->crtc[CGA_CRTC_HDISP] << 3) + 16;
                     else
-                        x = (cga->crtc[1] << 4) + 16;
+                        x = (cga->crtc[CGA_CRTC_HDISP] << 4) + 16;
                     cga->lastline++;
 
                     xs_temp = x;
@@ -657,7 +662,7 @@ cga_poll(void *priv)
                         if (!enable_overscan)
                             xs_temp -= 16;
 
-                        if ((cga->cgamode & 8) && ((xs_temp != xsize) ||
+                        if ((cga->cgamode & CGA_MODE_FLAG_VIDEO_ENABLE) && ((xs_temp != xsize) ||
                             (ys_temp != ysize) || video_force_resize_get())) {
                             xsize = xs_temp;
                             ysize = ys_temp;
@@ -691,15 +696,15 @@ cga_poll(void *priv)
 
                     video_res_x = xsize;
                     video_res_y = ysize;
-                    if (cga->cgamode & 1) {
+                    if (cga->cgamode & CGA_MODE_FLAG_HIGHRES) {
                         video_res_x /= 8;
-                        video_res_y /= cga->crtc[9] + 1;
+                        video_res_y /= cga->crtc[CGA_CRTC_MAX_SCANLINE_ADDR] + 1;
                         video_bpp = 0;
-                    } else if (!(cga->cgamode & 2)) {
+                    } else if (!(cga->cgamode & CGA_MODE_FLAG_GRAPHICS)) {
                         video_res_x /= 16;
-                        video_res_y /= cga->crtc[9] + 1;
+                        video_res_y /= cga->crtc[CGA_CRTC_MAX_SCANLINE_ADDR] + 1;
                         video_bpp = 0;
-                    } else if (!(cga->cgamode & 16)) {
+                    } else if (!(cga->cgamode & CGA_MODE_FLAG_HIGHRES_GRAPHICS)) {
                         video_res_x /= 2;
                         video_bpp = 2;
                     } else
@@ -717,11 +722,11 @@ cga_poll(void *priv)
         }
         if (cga->cgadispon)
             cga->cgastat &= ~1;
-        if (cga->sc == (cga->crtc[10] & 31) || ((cga->crtc[8] & 3) == 3 &&
-            cga->sc == ((cga->crtc[10] & 31) >> 1)))
+        if (cga->sc == (cga->crtc[CGA_CRTC_CURSOR_START] & 31) || ((cga->crtc[CGA_CRTC_INTERLACE] & 3) == 3 &&
+            cga->sc == ((cga->crtc[CGA_CRTC_CURSOR_START] & 31) >> 1)))
             cga->con = 1;
-        if (cga->cgadispon && (cga->cgamode & 1)) {
-            for (x = 0; x < (cga->crtc[1] << 1); x++)
+        if (cga->cgadispon && (cga->cgamode & CGA_MODE_FLAG_HIGHRES)) {
+            for (x = 0; x < (cga->crtc[CGA_CRTC_HDISP] << 1); x++)
                 cga->charbuffer[x] = cga->vram[((cga->ma << 1) + x) & 0x3fff];
         }
     }
diff --git a/src/video/vid_colorplus.c b/src/video/vid_colorplus.c
index 6c66175c1..7daba018e 100644
--- a/src/video/vid_colorplus.c
+++ b/src/video/vid_colorplus.c
@@ -42,9 +42,6 @@
 #define COLORPLUS_320x200_MODE 0x10 /* 320x200x16 mode active */
 #define COLORPLUS_EITHER_MODE  0x30 /* Either mode active */
 
-/* Bits in the CGA graphics mode register */
-#define CGA_GRAPHICS_MODE 0x02 /* CGA graphics mode selected? */
-
 #define CGA_RGB           0
 #define CGA_COMPOSITE     1
 
@@ -80,7 +77,7 @@ colorplus_write(uint32_t addr, uint8_t val, void *priv)
 {
     colorplus_t *colorplus = (colorplus_t *) priv;
 
-    if ((colorplus->control & COLORPLUS_PLANE_SWAP) && (colorplus->control & COLORPLUS_EITHER_MODE) && (colorplus->cga.cgamode & CGA_GRAPHICS_MODE)) {
+    if ((colorplus->control & COLORPLUS_PLANE_SWAP) && (colorplus->control & COLORPLUS_EITHER_MODE) && (colorplus->cga.cgamode & CGA_MODE_FLAG_GRAPHICS)) {
         addr ^= 0x4000;
     } else if (!(colorplus->control & COLORPLUS_EITHER_MODE)) {
         addr &= 0x3FFF;
@@ -99,7 +96,7 @@ colorplus_read(uint32_t addr, void *priv)
 {
     colorplus_t *colorplus = (colorplus_t *) priv;
 
-    if ((colorplus->control & COLORPLUS_PLANE_SWAP) && (colorplus->control & COLORPLUS_EITHER_MODE) && (colorplus->cga.cgamode & CGA_GRAPHICS_MODE)) {
+    if ((colorplus->control & COLORPLUS_PLANE_SWAP) && (colorplus->control & COLORPLUS_EITHER_MODE) && (colorplus->cga.cgamode & CGA_MODE_FLAG_GRAPHICS)) {
         addr ^= 0x4000;
     } else if (!(colorplus->control & COLORPLUS_EITHER_MODE)) {
         addr &= 0x3FFF;
@@ -140,7 +137,7 @@ colorplus_poll(void *priv)
 
     /* If one of the extra modes is not selected, drop down to the CGA
      * drawing code. */
-    if (!((colorplus->control & COLORPLUS_EITHER_MODE) && (colorplus->cga.cgamode & CGA_GRAPHICS_MODE))) {
+    if (!((colorplus->control & COLORPLUS_EITHER_MODE) && (colorplus->cga.cgamode & CGA_MODE_FLAG_GRAPHICS))) {
         cga_poll(&colorplus->cga);
         return;
     }
@@ -229,7 +226,6 @@ colorplus_poll(void *priv)
         }
         if (colorplus->cga.sc == (colorplus->cga.crtc[11] & 31) || ((colorplus->cga.crtc[8] & 3) == 3 && colorplus->cga.sc == ((colorplus->cga.crtc[11] & 31) >> 1))) {
             colorplus->cga.con  = 0;
-            colorplus->cga.coff = 1;
         }
         if ((colorplus->cga.crtc[8] & 3) == 3 && colorplus->cga.sc == (colorplus->cga.crtc[9] >> 1))
             colorplus->cga.maback = colorplus->cga.ma;
diff --git a/src/video/vid_compaq_cga.c b/src/video/vid_compaq_cga.c
index 13fc399eb..f9fec32d0 100644
--- a/src/video/vid_compaq_cga.c
+++ b/src/video/vid_compaq_cga.c
@@ -269,7 +269,6 @@ compaq_cga_poll(void *priv)
 
         if (self->cga.sc == (self->cga.crtc[11] & 31) || ((self->cga.crtc[8] & 3) == 3 && self->cga.sc == ((self->cga.crtc[11] & 31) >> 1))) {
             self->cga.con  = 0;
-            self->cga.coff = 1;
         }
         if ((self->cga.crtc[8] & 3) == 3 && self->cga.sc == (self->cga.crtc[9] >> 1))
             self->cga.maback = self->cga.ma;
diff --git a/src/video/vid_hercules.c b/src/video/vid_hercules.c
index af8ad08f8..cf8ad8cf3 100644
--- a/src/video/vid_hercules.c
+++ b/src/video/vid_hercules.c
@@ -399,7 +399,6 @@ hercules_poll(void *priv)
 
         if (dev->sc == (dev->crtc[11] & 31) || ((dev->crtc[8] & 3) == 3 && dev->sc == ((dev->crtc[11] & 31) >> 1))) {
             dev->con  = 0;
-            dev->coff = 1;
         }
 
         if (dev->vadj) {
diff --git a/src/video/vid_herculesplus.c b/src/video/vid_herculesplus.c
index fb42c3022..42c68bf54 100644
--- a/src/video/vid_herculesplus.c
+++ b/src/video/vid_herculesplus.c
@@ -77,7 +77,7 @@ typedef struct {
     int      linepos, displine;
     int      vc, sc;
     uint16_t ma, maback;
-    int      con, coff, cursoron;
+    int      con, cursoron;
     int      dispon, blink;
     int      vsynctime;
     int      vadj;
@@ -536,7 +536,6 @@ herculesplus_poll(void *priv)
 
         if (dev->sc == (dev->crtc[11] & 31) || ((dev->crtc[8] & 3) == 3 && dev->sc == ((dev->crtc[11] & 31) >> 1))) {
             dev->con  = 0;
-            dev->coff = 1;
         }
         if (dev->vadj) {
             dev->sc++;
diff --git a/src/video/vid_incolor.c b/src/video/vid_incolor.c
index d9b48f43a..034d54045 100644
--- a/src/video/vid_incolor.c
+++ b/src/video/vid_incolor.c
@@ -167,7 +167,7 @@ typedef struct {
     int      linepos, displine;
     int      vc, sc;
     uint16_t ma, maback;
-    int      con, coff, cursoron;
+    int      con, cursoron;
     int      dispon, blink;
     int      vsynctime;
     int      vadj;
@@ -899,7 +899,6 @@ incolor_poll(void *priv)
 
         if (dev->sc == (dev->crtc[11] & 31) || ((dev->crtc[8] & 3) == 3 && dev->sc == ((dev->crtc[11] & 31) >> 1))) {
             dev->con  = 0;
-            dev->coff = 1;
         }
 
         if (dev->vadj) {
diff --git a/src/video/vid_mda.c b/src/video/vid_mda.c
index 7b6e54806..70ca375fd 100644
--- a/src/video/vid_mda.c
+++ b/src/video/vid_mda.c
@@ -200,7 +200,6 @@ mda_poll(void *priv)
         }
         if (mda->sc == (mda->crtc[11] & 31) || ((mda->crtc[8] & 3) == 3 && mda->sc == ((mda->crtc[11] & 31) >> 1))) {
             mda->con  = 0;
-            mda->coff = 1;
         }
         if (mda->vadj) {
             mda->sc++;
diff --git a/src/video/vid_nga.c b/src/video/vid_nga.c
index ef1c6cd40..5fc81109c 100644
--- a/src/video/vid_nga.c
+++ b/src/video/vid_nga.c
@@ -392,7 +392,6 @@ nga_poll(void *priv)
                 /* cursor stop scanline */
                 if (nga->cga.sc == (nga->cga.crtc[11] & 31) || ((nga->cga.crtc[8] & 3) == 3 && nga->cga.sc == ((nga->cga.crtc[11] & 31) >> 1))) {
                     nga->cga.con  = 0;
-                    nga->cga.coff = 1;
                 }
                 /* interlaced and max scanline per char reached */
                 if ((nga->cga.crtc[8] & 3) == 3 && nga->cga.sc == (nga->cga.crtc[9] >> 1))
diff --git a/src/video/vid_ogc.c b/src/video/vid_ogc.c
index a49cd8a22..162cb9073 100644
--- a/src/video/vid_ogc.c
+++ b/src/video/vid_ogc.c
@@ -407,7 +407,6 @@ ogc_poll(void *priv)
                 }
                 if (ogc->cga.sc == (ogc->cga.crtc[11] & 31) || ((ogc->cga.crtc[8] & 3) == 3 && ogc->cga.sc == ((ogc->cga.crtc[11] & 31) >> 1))) {
                     ogc->cga.con  = 0;
-                    ogc->cga.coff = 1;
                 }
                 if ((ogc->cga.crtc[8] & 3) == 3 && ogc->cga.sc == (ogc->cga.crtc[9] >> 1))
                     ogc->cga.maback = ogc->cga.ma;
diff --git a/src/video/vid_sigma.c b/src/video/vid_sigma.c
index d771260ed..c54af7119 100644
--- a/src/video/vid_sigma.c
+++ b/src/video/vid_sigma.c
@@ -158,7 +158,7 @@ typedef struct sigma_t {
     int linepos, displine;
     int sc, vc;
     int cgadispon;
-    int con, coff, cursoron, cgablink;
+    int con, cursoron, cgablink;
     int vsynctime, vadj;
     int oddeven;
 
@@ -676,7 +676,6 @@ sigma_poll(void *priv)
         }
         if (sigma->sc == (sigma->crtc[11] & 31) || ((sigma->crtc[8] & 3) == 3 && sigma->sc == ((sigma->crtc[11] & 31) >> 1))) {
             sigma->con  = 0;
-            sigma->coff = 1;
         }
         if ((sigma->crtc[8] & 3) == 3 && sigma->sc == (sigma->crtc[9] >> 1))
             sigma->maback = sigma->ma;