diff --git a/src/include/86box/vid_cga.h b/src/include/86box/vid_cga.h
index 8ad7b7b98..00016e6c7 100644
--- a/src/include/86box/vid_cga.h
+++ b/src/include/86box/vid_cga.h
@@ -29,7 +29,7 @@ typedef enum cga_mode_flags_e
     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 the 
+    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;
 
@@ -51,11 +51,22 @@ typedef enum cga_crtc_registers_e
     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 addres low 8 bits
-    CGA_CRTC_LIGHT_PEN_ADDR_HIGH = 0x10,
-    CGA_CRTC_LIGHT_PEN_ADDR_LOW = 0x11,
+    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;
+
 typedef struct cga_t {
     mem_mapping_t mapping;
 
diff --git a/src/video/vid_cga.c b/src/video/vid_cga.c
index bb0d04248..578f7419e 100644
--- a/src/video/vid_cga.c
+++ b/src/video/vid_cga.c
@@ -89,14 +89,14 @@ 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) {
-                // Update the timings if we are writing any invalid CRTC register or a valid CRTC register 
+                // 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;
@@ -104,7 +104,7 @@ cga_out(uint16_t addr, uint8_t val, void *priv)
                 }
             }
             return;
-        case 0x3D8:
+        case CGA_REGISTER_MODE_CONTROL:
             old          = cga->cgamode;
             cga->cgamode = val;
 
@@ -115,18 +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);
@@ -148,21 +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);