diff --git a/src/vid_ati28800.c b/src/vid_ati28800.c
index 1c8326bc0..bed6c9775 100644
--- a/src/vid_ati28800.c
+++ b/src/vid_ati28800.c
@@ -42,26 +42,26 @@ void ati28800_out(uint16_t addr, uint8_t val, void *p)
                 ati28800->index = val;
                 break;
                 case 0x1cf:
-                ati28800->regs[ati28800->index] = val;
-                switch (ati28800->index)
+                ati28800->regs[ati28800->index & 0x3f] = val;
+                switch (ati28800->index & 0x3f)
                 {
-			case 0xad:
-			if (gfxcard == GFX_VGAWONDERXL24)
+			case 0x2d:
+			if ((gfxcard == GFX_VGAWONDERXL24) && (val & 8))
 			{
 				svga->charseta = (svga->charseta & 0x3ffff) | ((((uint32_t) val) >> 4) << 18);
 				svga->charsetb = (svga->charsetb & 0x3ffff) | ((((uint32_t) val) >> 4) << 18);
 			}
 			break;
 
-                        case 0xb2:
-                        case 0xbe:
-                        if (ati28800->regs[0xbe] & 8) /*Read/write bank mode*/
+                        case 0x32:
+                        case 0x3e:
+                        if (ati28800->regs[0x3e] & 8) /*Read/write bank mode*/
                         {
-                                svga->read_bank  = ((ati28800->regs[0xb2] >> 5) & 7) * 0x10000;
-                                svga->write_bank = ((ati28800->regs[0xb2] >> 1) & 7) * 0x10000;
+                                svga->read_bank  = ((ati28800->regs[0x32] >> 5) & 7) * 0x10000;
+                                svga->write_bank = ((ati28800->regs[0x32] >> 1) & 7) * 0x10000;
                         }
                         else                    /*Single bank mode*/
-                                svga->read_bank = svga->write_bank = ((ati28800->regs[0xb2] >> 1) & 7) * 0x10000;
+                                svga->read_bank = svga->write_bank = ((ati28800->regs[0x32] >> 1) & 7) * 0x10000;
                         break;
                         case 0xb3:
                         ati_eeprom_write(&ati28800->eeprom, val & 8, val & 2, val & 1);
@@ -110,20 +110,20 @@ uint8_t ati28800_in(uint16_t addr, void *p)
                 temp = ati28800->index;
                 break;
                 case 0x1cf:
-                switch (ati28800->index)
+                switch (ati28800->index & 0x3f)
                 {
-			case 0xaa:
+			case 0x2a:
 			temp = (gfxcard == GFX_VGAWONDERXL24) ? 6 : 5;
 			break;
 
-                        case 0xb7:
-                        temp = ati28800->regs[ati28800->index] & ~8;
+                        case 0x37:
+                        temp = ati28800->regs[ati28800->index & 0x3f] & ~8;
                         if (ati_eeprom_read(&ati28800->eeprom))
                                 temp |= 8;
                         break;
                         
                         default:
-                        temp = ati28800->regs[ati28800->index];
+                        temp = ati28800->regs[ati28800->index & 0x3f];
                         break;
                 }
                 break;
@@ -187,7 +187,7 @@ void ati28800_svga_recalctimings(ati28800_t *ati28800)
         svga->hdisp++;
 
         svga->htotal = svga->crtc[0];
-	if ((ati28800->regs[0xad] & 8) && (gfxcard == GFX_VGAWONDERXL24))  svga->htotal |= (ati28800->regs[0xad] & 1) ? 0x100 : 0;
+	if ((ati28800->regs[0x2d] & 8) && (gfxcard == GFX_VGAWONDERXL24))  svga->htotal |= (ati28800->regs[0x2d] & 1) ? 0x100 : 0;
         svga->htotal += 6; /*+6 is required for Tyrian*/
 
         svga->rowoffset = svga->crtc[0x13];
@@ -312,7 +312,7 @@ void ati28800_recalctimings(svga_t *svga)
 #ifndef RELEASE_BUILD
         pclog("ati28800_recalctimings\n");
 #endif
-        if (!svga->scrblank && (ati28800->regs[0xb0] & 0x20)) /*Extended 256 colour modes*/
+        if (!svga->scrblank && (ati28800->regs[0x30] & 0x20)) /*Extended 256 colour modes*/
         {
 #ifndef RELEASE_BUILD
                 pclog("8bpp_highres\n");
diff --git a/src/vid_ati_mach64.c b/src/vid_ati_mach64.c
index 2f6ac5575..4fdf41f0b 100644
--- a/src/vid_ati_mach64.c
+++ b/src/vid_ati_mach64.c
@@ -276,8 +276,11 @@ void mach64_out(uint16_t addr, uint8_t val, void *p)
                 mach64->regs[mach64->index & 0x3f] = val;
                 if ((mach64->index & 0x3f) == 0x2d)
 		{
-			svga->charseta = (svga->charseta & 0x3ffff) | ((((uint32_t) val) >> 4) << 18);
-			svga->charsetb = (svga->charsetb & 0x3ffff) | ((((uint32_t) val) >> 4) << 18);
+			if (val & 8)
+			{
+				svga->charseta = (svga->charseta & 0x3ffff) | ((((uint32_t) val) >> 4) << 18);
+				svga->charsetb = (svga->charsetb & 0x3ffff) | ((((uint32_t) val) >> 4) << 18);
+			}
 			break;
 		}
                 if ((mach64->index & 0x3f) == 0x36)
diff --git a/src/vid_svga.c b/src/vid_svga.c
index a487405f4..160d19430 100644
--- a/src/vid_svga.c
+++ b/src/vid_svga.c
@@ -136,8 +136,10 @@ void svga_out(uint16_t addr, uint8_t val, void *p)
                         svga->writemask = val & 0xf; 
                         break;
                         case 3:
-                        svga->charsetb = (((val >> 2) & 3) * 0x10000) + 2;
-                        svga->charseta = ((val & 3)  * 0x10000) + 2;
+                        svga->charsetb &= ~0x3ffff;
+                        svga->charseta &= ~0x3ffff;
+                        svga->charsetb |= (((val >> 2) & 3) * 0x10000) + 2;
+                        svga->charseta |= ((val & 3)  * 0x10000) + 2;
                         if (val & 0x10)
                                 svga->charseta += 0x8000;
                         if (val & 0x20)
diff --git a/src/vid_svga_render.c b/src/vid_svga_render.c
index e95700a9c..ca45daace 100644
--- a/src/vid_svga_render.c
+++ b/src/vid_svga_render.c
@@ -128,6 +128,7 @@ void svga_render_text_80(svga_t *svga)
 			attr = svga->vram[(svga->ma << 1) + 1];
                         if (attr & 8) charaddr = svga->charsetb + (chr * 128);
                         else          charaddr = svga->charseta + (chr * 128);
+			pclog("Character address is: %08X\n", charaddr);
 
                         if (drawcursor) 
                         {