diff --git a/src/include/86box/vid_svga.h b/src/include/86box/vid_svga.h
index f644c2b63..32bfbfd2f 100644
--- a/src/include/86box/vid_svga.h
+++ b/src/include/86box/vid_svga.h
@@ -118,16 +118,16 @@ typedef struct svga_t {
     int vram_display_mask;
     int vidclock;
     int dots_per_clock;
-    int hblank_ext;
     int hwcursor_on;
     int dac_hwcursor_on;
     int overlay_on;
     int set_override;
     int hblankstart;
     int hblankend;
-    int hblank_sub;
     int hblank_end_val;
     int hblank_end_len;
+    int hblank_end_mask;
+    int hblank_sub;
     int packed_4bpp;
     int ati_4color;
 
diff --git a/src/video/vid_ati28800.c b/src/video/vid_ati28800.c
index 1f2b69e25..be9654aca 100644
--- a/src/video/vid_ati28800.c
+++ b/src/video/vid_ati28800.c
@@ -429,8 +429,7 @@ ati28800_recalctimings(svga_t *svga)
         svga->hdisp <<= 1;
         svga->htotal <<= 1;
         svga->rowoffset <<= 1;
-        svga->hblankstart <<= 1;
-        svga->hblank_end_val <<= 1;
+        svga->dots_per_clock <<= 1;
         svga->gdcreg[5] &= ~0x40;
     }
 
@@ -446,8 +445,7 @@ ati28800_recalctimings(svga_t *svga)
     if ((ati28800->regs[0xb6] & 0x18) == 8) {
         svga->hdisp <<= 1;
         svga->htotal <<= 1;
-        svga->hblankstart <<= 1;
-        svga->hblank_end_val <<= 1;
+        svga->dots_per_clock <<= 1;
         svga->ati_4color = 1;
     } else
         svga->ati_4color = 0;
diff --git a/src/video/vid_ati_mach8.c b/src/video/vid_ati_mach8.c
index de40dc24e..ff6024677 100644
--- a/src/video/vid_ati_mach8.c
+++ b/src/video/vid_ati_mach8.c
@@ -2485,6 +2485,9 @@ ati8514_recalctimings(svga_t *svga)
 {
     const mach_t *mach = (mach_t *) svga->ext8514;
     ibm8514_t    *dev  = (ibm8514_t *) svga->dev8514;
+    uint32_t      dot;
+    uint32_t      adj_dot;
+    uint32_t      eff_mask;
 
     mach_log("ON0=%d, ON1=%d, vgahdisp=%d.\n", dev->on[0], dev->on[1], svga->hdisp);
     if (dev->on[0] || dev->on[1]) {
@@ -2528,19 +2531,26 @@ ati8514_recalctimings(svga_t *svga)
         svga->map8 = dev->pallook;
         svga->render8514 = ibm8514_render_8bpp;
 
-        dev->hblankend = (dev->h_blankstart & ~0x3f) | dev->h_blank_end_val;
-        if (dev->hblankend <= dev->h_blankstart)
-            dev->hblankend += 0x40;
-
-        dev->hblankend += dev->hblank_ext;
-
+        dot = svga->hblankstart;
+        adj_dot = svga->hblankstart;
+        eff_mask = 0x0000003f;
         dev->hblank_sub = 0;
-        if (dev->hblankend > dev->h_total) {
-            dev->hblankend &= 0x3f;
-            dev->hblank_sub = dev->hblankend + 1;
 
-            dev->h_disp -= dev->hblank_sub;
+        while (1) {
+            if (dot == dev->h_total)
+                dot = 0;
+
+            if (adj_dot >= dev->h_total)
+                dev->hblank_sub++;
+
+            if ((dot & 0x0000003f) == (svga->hblank_end_val & 0x0000003f))
+                break;
+
+            dot++;
+            adj_dot++;
         }
+
+        dev->h_disp -= dev->hblank_sub);
     } else {
         if (!(svga->gdcreg[6] & 1) && !(svga->attrregs[0x10] & 1)) { /*Text mode*/
             if (svga->seqregs[1] & 8) {                              /*40 column*/
@@ -2582,8 +2592,7 @@ mach_recalctimings(svga_t *svga)
     if ((mach->regs[0xb6] & 0x18) >= 0x10) {
         svga->hdisp <<= 1;
         svga->htotal <<= 1;
-        svga->hblankstart <<= 1;
-        svga->hblank_end_val <<= 1;
+        svga->dots_per_clock <<= 1;
         svga->rowoffset <<= 1;
         svga->gdcreg[5] &= ~0x40;
     }
@@ -2601,8 +2610,7 @@ mach_recalctimings(svga_t *svga)
         if ((mach->regs[0xb6] & 0x18) == 8) {
             svga->hdisp <<= 1;
             svga->htotal <<= 1;
-            svga->hblankstart <<= 1;
-            svga->hblank_end_val <<= 1;
+            svga->dots_per_clock <<= 1;
             svga->ati_4color = 1;
         } else
             svga->ati_4color = 0;
diff --git a/src/video/vid_cl54xx.c b/src/video/vid_cl54xx.c
index aaa208a23..7ae985e95 100644
--- a/src/video/vid_cl54xx.c
+++ b/src/video/vid_cl54xx.c
@@ -1766,6 +1766,8 @@ gd54xx_recalctimings(svga_t *svga)
         svga->hblank_end_val = (svga->crtc[3] & 0x1f) | ((svga->crtc[5] & 0x80) ? 0x20 : 0x00) |
                                (((svga->crtc[0x1a] >> 4) & 3) << 6);
 
+        svga->hblank_end_mask = 0x0000007f;
+
         if (svga->crtc[0x1b] & 0x20) {
             svga->hblankstart = svga->crtc[1] + ((svga->crtc[3] >> 5) & 3) + 1;
             svga->hblank_end_val = ((svga->crtc[3] >> 5) & 3);
@@ -1774,9 +1776,6 @@ gd54xx_recalctimings(svga_t *svga)
 	    if (!svga->scrblank && svga->attr_palette_enable)
                 svga->dots_per_clock = (svga->seqregs[1] & 8) ? 16 : 8;
 
-            /* No overscan in this mode. */
-            svga->hblank_overscan = 0;
-
             svga->monitor->mon_overscan_y = 0;
             svga->monitor->mon_overscan_x = 0;
 
@@ -1801,8 +1800,7 @@ gd54xx_recalctimings(svga_t *svga)
             svga->render = svga_render_8bpp_highres;
             if ((svga->dispend == 512) && !svga->interlace && gd54xx_is_5434(svga)) {
                 svga->hdisp <<= 1;
-                svga->hblankstart <<= 1;
-                svga->hblank_end_val <<= 1;
+                svga->dots_per_clock <<= 1;
             }
         }
     } else if (svga->gdcreg[5] & 0x40)
diff --git a/src/video/vid_et4000.c b/src/video/vid_et4000.c
index f5f9ad813..6d52fc91b 100644
--- a/src/video/vid_et4000.c
+++ b/src/video/vid_et4000.c
@@ -668,8 +668,7 @@ et4000_recalctimings(svga_t *svga)
         svga->htotal += 256;
     if (svga->attrregs[0x16] & 0x20) {
         svga->hdisp <<= 1;
-        svga->hblankstart <<= 1;
-        svga->hblank_end_val <<= 1;
+        svga->dots_per_clock <<= 1;
     }
 
     switch (((svga->miscout >> 2) & 3) | ((svga->crtc[0x34] << 1) & 4)) {
diff --git a/src/video/vid_et4000w32.c b/src/video/vid_et4000w32.c
index f3cac960b..259fefffb 100644
--- a/src/video/vid_et4000w32.c
+++ b/src/video/vid_et4000w32.c
@@ -450,8 +450,7 @@ et4000w32p_recalctimings(svga_t *svga)
         svga->htotal += 256;
     if (svga->attrregs[0x16] & 0x20) {
         svga->hdisp <<= 1;
-        svga->hblankstart <<= 1;
-        svga->hblank_end_val <<= 1;
+        svga->dots_per_clock <<= 1;
     }
 
     svga->clock = (cpuclock * (double) (1ULL << 32)) / svga->getclock((svga->miscout >> 2) & 3, svga->clock_gen);
@@ -502,8 +501,7 @@ et4000w32p_recalctimings(svga_t *svga)
         case 16:
             if ((svga->gdcreg[6] & 1) || (svga->attrregs[0x10] & 1)) {
                 svga->hdisp >>= 1;
-                svga->hblankstart >>= 1;
-                svga->hblank_end_val >>= 1;
+                svga->dots_per_clock >>= 1;
             }
             if (et4000->type <= ET4000W32P_REVC) {
                 if (et4000->type == ET4000W32P_REVC) {
@@ -515,8 +513,7 @@ et4000w32p_recalctimings(svga_t *svga)
             break;
         case 24:
             svga->hdisp /= 3;
-            svga->hblankstart /= 3;
-            svga->hblank_end_val /= 3;
+            svga->dots_per_clock /= 3;
             if (et4000->type <= ET4000W32P_REVC)
                 et4000->adjust_cursor = 2;
             if ((et4000->type == ET4000W32P_DIAMOND) && ((svga->hdisp == (640 / 2)) || (svga->hdisp == 1232))) {
diff --git a/src/video/vid_mga.c b/src/video/vid_mga.c
index bc335fc9c..088085355 100644
--- a/src/video/vid_mga.c
+++ b/src/video/vid_mga.c
@@ -976,11 +976,10 @@ mystique_recalctimings(svga_t *svga)
         svga->hdisp_time    = svga->hdisp;
         svga->rowoffset     = svga->crtc[0x13] | ((mystique->crtcext_regs[0] & CRTCX_R0_OFFSET_MASK) << 4);
 
-        svga->dots_per_clock = 8;
-        svga->hblank_end_val = (svga->crtc[3] & 0x1f) | (((svga->crtc[5] & 0x80) >> 7) << 5) |
-                               (((mystique->crtcext_regs[1] & 0x40) >> 6) << 6);
-
-        svga->hblank_overscan = 0;
+        svga->dots_per_clock  = 8;
+        svga->hblank_end_val  = (svga->crtc[3] & 0x1f) | (((svga->crtc[5] & 0x80) >> 7) << 5) |
+                                (((mystique->crtcext_regs[1] & 0x40) >> 6) << 6);
+        svga->hblank_end_mask = 0x0000007f;
 
         if (mystique->type != MGA_2164W && mystique->type != MGA_2064W)
             svga->lut_map = !!(mystique->xmiscctrl & XMISCCTRL_RAMCS);
diff --git a/src/video/vid_s3.c b/src/video/vid_s3.c
index ad7e77aa7..d8691ad77 100644
--- a/src/video/vid_s3.c
+++ b/src/video/vid_s3.c
@@ -3153,6 +3153,17 @@ s3_recalctimings(svga_t *svga)
     int   clk_sel = (svga->miscout >> 2) & 3;
     uint8_t mask = 0xc0;
 
+    if (svga->crtc[0x33] & 0x20) {
+        /* In this mode, the dots per clock are always 8 or 16, never 9 or 18. */
+        if (!svga->scrblank && svga->attr_palette_enable)
+            svga->dots_per_clock = (svga->seqregs[1] & 8) ? 16 : 8;
+    } else {
+        if (!svga->scrblank && svga->attr_palette_enable && (svga->crtc[0x43] & 0x80)) {
+            /* TODO: In case of bug reports, disable 9-dots-wide character clocks in graphics modes. */
+            svga->dots_per_clock = ((svga->seqregs[1] & 1) ? 16 : 18);
+        }
+    }
+
     svga->hdisp = svga->hdisp_old;
 
     svga->ma_latch |= (s3->ma_ext << 16);
@@ -3255,24 +3266,15 @@ s3_recalctimings(svga_t *svga)
                             ((svga->crtc[3] >> 5) & 3) + 1;
         svga->hblank_end_val = ((svga->crtc[3] >> 5) & 3);
 
-        /* In this mode, the dots per clock are always 8 or 16, never 9 or 18. */
-        if (!svga->scrblank && svga->attr_palette_enable)
-            svga->dots_per_clock = (svga->seqregs[1] & 8) ? 16 : 8;
-
-        /* No overscan in this mode. */
-        svga->hblank_overscan = 0;
-
         svga->monitor->mon_overscan_y = 0;
         svga->monitor->mon_overscan_x = 0;
 
         /* Also make sure vertical blanking starts on display end. */
         svga->vblankstart = svga->dispend;
-    } else if (s3->chip >= S3_86C801) {
-        if (!svga->scrblank && svga->attr_palette_enable && (svga->crtc[0x43] & 0x80)) {
-            /* TODO: In case of bug reports, disable 9-dots-wide character clocks in graphics modes. */
-            svga->dots_per_clock = ((svga->seqregs[1] & 1) ? 16 : 18);
-        }
 
+        if (s3->chip >= S3_VISION964)
+            svga->hblank_end_mask  = 0x7f;
+    } else if (s3->chip >= S3_86C801) {
         svga->hblankstart    = (((svga->crtc[0x5d] & 0x04) >> 2) << 8) + svga->crtc[2] + 1;
 
         if (s3->chip >= S3_VISION964) {
@@ -3280,8 +3282,9 @@ s3_recalctimings(svga_t *svga)
                      The datasheets for the pre-Trio64V+ cards say +64, which implies bit 6,
                      and, contrary to VGADOC, it also exists on Trio32, Trio64, Vision868,
                      and Vision968. */
-            svga->hblank_end_val = (svga->crtc[3] & 0x1f) | (((svga->crtc[5] & 0x80) >> 7) << 5) |
-                                   (((svga->crtc[0x5d] & 0x08) >> 3) << 6);
+            svga->hblank_end_val  = (svga->crtc[3] & 0x1f) | (((svga->crtc[5] & 0x80) >> 7) << 5) |
+                                    (((svga->crtc[0x5d] & 0x08) >> 3) << 6);
+            svga->hblank_end_mask  = 0x7f;
         }
     }
 
@@ -3329,20 +3332,17 @@ s3_recalctimings(svga_t *svga)
                                 switch (s3->width) {
                                     case 1280:
                                         svga->hdisp <<= 1;
-                                        svga->hblankstart <<= 1;
-                                        svga->hblank_end_val <<= 1;
+                                        svga->dots_per_clock <<= 1;
                                         break;
                                     case 2048: /*Account for the 1280x1024 resolution*/
                                         switch (svga->hdisp) {
                                             case 320:
                                                 svga->hdisp <<= 2;
-                                                svga->hblankstart <<= 2;
-                                                svga->hblank_end_val <<= 2;
+                                                svga->dots_per_clock <<= 2;
                                                 break;
                                             case 640:
                                                 svga->hdisp <<= 1;
-                                                svga->hblankstart <<= 1;
-                                                svga->hblank_end_val <<= 1;
+                                                svga->dots_per_clock <<= 1;
                                                 break;
                                             default:
                                                 break;
@@ -3363,8 +3363,7 @@ s3_recalctimings(svga_t *svga)
                                 switch (s3->width) {
                                     case 640:
                                         svga->hdisp >>= 1;
-                                        svga->hblankstart >>= 1;
-                                        svga->hblank_end_val >>= 1;
+                                        svga->dots_per_clock >>= 1;
                                         break;
                                     default:
                                         break;
@@ -3382,8 +3381,7 @@ s3_recalctimings(svga_t *svga)
                                     case 1280:
                                     case 1600:
                                         svga->hdisp <<= 1;
-                                        svga->hblankstart <<= 1;
-                                        svga->hblank_end_val <<= 1;
+                                        svga->dots_per_clock <<= 1;
                                     default:
                                         break;
                                 }
@@ -3398,29 +3396,16 @@ s3_recalctimings(svga_t *svga)
                             case S3_PHOENIX_VISION968:
                             case S3_NUMBER9_9FX_771:
                                 svga->hdisp <<= 1;
-                                svga->hblankstart <<= 1;
-                                svga->hblank_end_val <<= 1;
+                                svga->dots_per_clock <<= 1;
+                                if (svga->hdisp == 832)
+                                    svga->hdisp -= 32;
                                 break;
-                            case S3_SPEA_MERCURY_P64V:
                             case S3_ELSAWIN2KPROX:
                                 switch (s3->width) {
                                     case 1280:
                                     case 1600:
                                         svga->hdisp <<= 1;
-                                        svga->hblankstart <<= 1;
-                                        svga->hblank_end_val <<= 1;
-                                    default:
-                                        break;
-                                }
-                                break;
-                            case S3_MIROVIDEO40SV_ERGO_968:
-                                switch (s3->width) {
-                                    case 1152:
-                                    case 1280:
-                                        svga->hdisp <<= 1;
-                                        svga->hblankstart <<= 1;
-                                        svga->hblank_end_val <<= 1;
-                                        break;
+                                        svga->dots_per_clock <<= 1;
                                     default:
                                         break;
                                 }
@@ -3464,16 +3449,14 @@ s3_recalctimings(svga_t *svga)
                     case S3_86C911:
                     case S3_86C924:
                         svga->hdisp >>= 1;
-                        svga->hblankstart >>= 1;
-                        svga->hblank_end_val >>= 1;
+                        svga->dots_per_clock >>= 1;
                         break;
 
                     case S3_86C801:
                         switch (s3->card_type) {
                             case S3_PHOENIX_86C801:
                                 svga->hdisp >>= 1;
-                                svga->hblankstart >>= 1;
-                                svga->hblank_end_val >>= 1;
+                                svga->dots_per_clock >>= 1;
                                 break;
 
                             default:
@@ -3487,22 +3470,19 @@ s3_recalctimings(svga_t *svga)
                             case S3_PHOENIX_86C805:
                             case S3_86C805_ONBOARD:
                                 svga->hdisp >>= 1;
-                                svga->hblankstart >>= 1;
-                                svga->hblank_end_val >>= 1;
+                                svga->dots_per_clock >>= 1;
                                 break;
 
                             case S3_SPEA_MIRAGE_86C805:
                                 svga->hdisp >>= 1;
-                                svga->hblankstart >>= 1;
-                                svga->hblank_end_val >>= 1;
+                                svga->dots_per_clock >>= 1;
                                 switch (s3->width) {
                                     case 800:
                                     case 1024:
                                         if (svga->hdisp == 400) {
                                             /*SPEA specific drivers + its VBE RAM BIOS...*/
                                             svga->hdisp <<= 1;
-                                            svga->hblankstart <<= 1;
-                                            svga->hblank_end_val <<= 1;
+                                            svga->dots_per_clock <<= 1;
                                         }
                                         break;
                                     default:
@@ -3519,8 +3499,7 @@ s3_recalctimings(svga_t *svga)
                             case S3_METHEUS_86C928:
                                 if (!s3->color_16bit) {
                                     svga->hdisp <<= 1;
-                                    svga->hblankstart <<= 1;
-                                    svga->hblank_end_val <<= 1;
+                                    svga->dots_per_clock <<= 1;
                                 }
                                 switch (svga->hdisp) { /*This might be a driver issue*/
                                     case 800:
@@ -3544,8 +3523,7 @@ s3_recalctimings(svga_t *svga)
                                 switch (s3->width) {
                                     case 640:
                                         svga->hdisp >>= 1;
-                                        svga->hblankstart >>= 1;
-                                        svga->hblank_end_val >>= 1;
+                                        svga->dots_per_clock >>= 1;
                                         break;
                                     default:
                                         break;
@@ -3558,8 +3536,7 @@ s3_recalctimings(svga_t *svga)
                         break;
                     case S3_VISION864:
                         svga->hdisp >>= 1;
-                        svga->hblankstart >>= 1;
-                        svga->hblank_end_val >>= 1;
+                        svga->dots_per_clock >>= 1;
                         break;
                     case S3_VISION964:
                         switch (s3->card_type) {
@@ -3568,8 +3545,7 @@ s3_recalctimings(svga_t *svga)
                                     case 1280:
                                     case 1600:
                                         svga->hdisp <<= 1;
-                                        svga->hblankstart <<= 1;
-                                        svga->hblank_end_val <<= 1;
+                                        svga->dots_per_clock <<= 1;
                                         break;
                                     default:
                                         break;
@@ -3585,8 +3561,7 @@ s3_recalctimings(svga_t *svga)
                             case S3_PHOENIX_VISION868:
                             case S3_NUMBER9_9FX_531:
                                 svga->hdisp >>= 1;
-                                svga->hblankstart >>= 1;
-                                svga->hblank_end_val >>= 1;
+                                svga->dots_per_clock >>= 1;
                                 break;
 
                             default:
@@ -3598,8 +3573,7 @@ s3_recalctimings(svga_t *svga)
                             case S3_NUMBER9_9FX_771:
                             case S3_PHOENIX_VISION968:
                                 svga->hdisp <<= 1;
-                                svga->hblankstart <<= 1;
-                                svga->hblank_end_val <<= 1;
+                                svga->dots_per_clock <<= 1;
                                 /* TODO: Is this still needed? */
                                 if (svga->hdisp == 832)
                                     svga->hdisp -= 32;
@@ -3610,8 +3584,7 @@ s3_recalctimings(svga_t *svga)
                                     case 1280:
                                     case 1600:
                                         svga->hdisp <<= 1;
-                                        svga->hblankstart <<= 1;
-                                        svga->hblank_end_val <<= 1;
+                                        svga->dots_per_clock <<= 1;
                                         break;
                                     default:
                                         break;
@@ -3625,8 +3598,7 @@ s3_recalctimings(svga_t *svga)
                     case S3_TRIO64:
                     case S3_TRIO32:
                         svga->hdisp >>= 1;
-                        svga->hblankstart >>= 1;
-                        svga->hblank_end_val >>= 1;
+                        svga->dots_per_clock >>= 1;
                         break;
 
                     default:
@@ -3662,16 +3634,14 @@ s3_recalctimings(svga_t *svga)
                     case S3_86C911:
                     case S3_86C924:
                         svga->hdisp >>= 1;
-                        svga->hblankstart >>= 1;
-                        svga->hblank_end_val >>= 1;
+                        svga->dots_per_clock >>= 1;
                         break;
 
                     case S3_86C801:
                         switch (s3->card_type) {
                             case S3_PHOENIX_86C801:
                                 svga->hdisp >>= 1;
-                                svga->hblankstart >>= 1;
-                                svga->hblank_end_val >>= 1;
+                                svga->dots_per_clock >>= 1;
                                 break;
 
                             default:
@@ -3685,8 +3655,7 @@ s3_recalctimings(svga_t *svga)
                             case S3_PHOENIX_86C805:
                             case S3_86C805_ONBOARD:
                                 svga->hdisp >>= 1;
-                                svga->hblankstart >>= 1;
-                                svga->hblank_end_val >>= 1;
+                                svga->dots_per_clock >>= 1;
                                 break;
 
                             case S3_SPEA_MIRAGE_86C805:
@@ -3697,8 +3666,7 @@ s3_recalctimings(svga_t *svga)
                                         if (svga->hdisp == 400) {
                                             /*SPEA specific drivers + its VBE RAM BIOS...*/
                                             svga->hdisp <<= 1;
-                                            svga->hblankstart <<= 1;
-                                            svga->hblank_end_val <<= 1;
+                                            svga->dots_per_clock <<= 1;
                                         }
                                         break;
                                     default:
@@ -3714,8 +3682,7 @@ s3_recalctimings(svga_t *svga)
                         switch (s3->card_type) {
                             case S3_METHEUS_86C928:
                                 svga->hdisp <<= 1;
-                                svga->hblankstart <<= 1;
-                                svga->hblank_end_val <<= 1;
+                                svga->dots_per_clock <<= 1;
                                 switch (svga->hdisp) { /*This might be a driver issue*/
                                     case 800:
                                         s3->width = 1024;
@@ -3738,8 +3705,7 @@ s3_recalctimings(svga_t *svga)
                                 switch (s3->width) {
                                     case 640:
                                         svga->hdisp >>= 1;
-                                        svga->hblankstart >>= 1;
-                                        svga->hblank_end_val >>= 1;
+                                        svga->dots_per_clock >>= 1;
                                       break;
                                     default:
                                         break;
@@ -3752,16 +3718,14 @@ s3_recalctimings(svga_t *svga)
                         break;
                     case S3_VISION864:
                         svga->hdisp >>= 1;
-                        svga->hblankstart >>= 1;
-                        svga->hblank_end_val >>= 1;
+                        svga->dots_per_clock >>= 1;
                         break;
                     case S3_VISION868:
                         switch (s3->card_type) {
                             case S3_PHOENIX_VISION868:
                             case S3_NUMBER9_9FX_531:
                                 svga->hdisp >>= 1;
-                                svga->hblankstart >>= 1;
-                                svga->hblank_end_val >>= 1;
+                                svga->dots_per_clock >>= 1;
                                 break;
 
                             default:
@@ -3775,8 +3739,7 @@ s3_recalctimings(svga_t *svga)
                                     case 1280:
                                     case 1600:
                                         svga->hdisp <<= 1;
-                                        svga->hblankstart <<= 1;
-                                        svga->hblank_end_val <<= 1;
+                                        svga->dots_per_clock <<= 1;
                                         break;
                                     default:
                                         break;
@@ -3792,8 +3755,7 @@ s3_recalctimings(svga_t *svga)
                             case S3_NUMBER9_9FX_771:
                             case S3_PHOENIX_VISION968:
                                 svga->hdisp <<= 1;
-                                svga->hblankstart <<= 1;
-                                svga->hblank_end_val <<= 1;
+                                svga->dots_per_clock <<= 1;
                                 /* TODO: Is this still needed? */
                                 if (svga->hdisp == 832)
                                     svga->hdisp -= 32;
@@ -3804,8 +3766,7 @@ s3_recalctimings(svga_t *svga)
                                     case 1280:
                                     case 1600:
                                         svga->hdisp <<= 1;
-                                        svga->hblankstart <<= 1;
-                                        svga->hblank_end_val <<= 1;
+                                        svga->dots_per_clock <<= 1;
                                         break;
                                     default:
                                         break;
@@ -3819,8 +3780,7 @@ s3_recalctimings(svga_t *svga)
                     case S3_TRIO64:
                     case S3_TRIO32:
                         svga->hdisp >>= 1;
-                        svga->hblankstart >>= 1;
-                        svga->hblank_end_val >>= 1;
+                        svga->dots_per_clock >>= 1;
                         break;
 
                     default:
@@ -3863,8 +3823,7 @@ s3_recalctimings(svga_t *svga)
                         switch (s3->card_type) {
                             case S3_AMI_86C924:
                                 svga->hdisp = (svga->hdisp << 1) / 3;
-                                svga->hblankstart = (svga->hblankstart << 1) / 3;
-                                svga->hblank_end_val = (svga->hblank_end_val << 1) / 3;
+                                svga->dots_per_clock = (svga->dots_per_clock << 1) / 3;
                                 /* TODO: Is this still needed? */
                                 if (svga->hdisp == 645)
                                     svga->hdisp -= 5;
@@ -3878,8 +3837,7 @@ s3_recalctimings(svga_t *svga)
                             case S3_PHOENIX_86C801:
                             case S3_SPEA_MIRAGE_86C801:
                                 svga->hdisp = (svga->hdisp << 1) / 3;
-                                svga->hblankstart = (svga->hblankstart << 1) / 3;
-                                svga->hblank_end_val = (svga->hblank_end_val << 1) / 3;
+                                svga->dots_per_clock = (svga->dots_per_clock << 1) / 3;
                                 break;
                             default:
                                 break;
@@ -3893,8 +3851,7 @@ s3_recalctimings(svga_t *svga)
                             case S3_SPEA_MIRAGE_86C805:
                             case S3_86C805_ONBOARD:
                                 svga->hdisp = (svga->hdisp << 1) / 3;
-                                svga->hblankstart = (svga->hblankstart << 1) / 3;
-                                svga->hblank_end_val = (svga->hblank_end_val << 1) / 3;
+                                svga->dots_per_clock = (svga->dots_per_clock << 1) / 3;
                                 break;
                             default:
                                 break;
@@ -3904,8 +3861,7 @@ s3_recalctimings(svga_t *svga)
                         switch (s3->card_type) {
                             case S3_SPEA_MERCURY_LITE_PCI:
                                 svga->hdisp = (svga->hdisp << 1) / 3;
-                                svga->hblankstart = (svga->hblankstart << 1) / 3;
-                                svga->hblank_end_val = (svga->hblank_end_val << 1) / 3;
+                                svga->dots_per_clock = (svga->dots_per_clock << 1) / 3;
                                 break;
                             default:
                                 break;
@@ -3913,34 +3869,13 @@ s3_recalctimings(svga_t *svga)
                         break;
                     case S3_VISION864:
                         svga->hdisp = (svga->hdisp << 1) / 3;
-                        svga->hblankstart = (svga->hblankstart << 1) / 3;
-                        svga->hblank_end_val = (svga->hblank_end_val << 1) / 3;
-                        break;
-                    case S3_VISION968:
-                        switch (s3->card_type) {
-                            case S3_MIROVIDEO40SV_ERGO_968:
-                            case S3_SPEA_MERCURY_P64V:
-                                switch (s3->width) {
-                                    case 1280:
-                                        svga->hdisp = ((svga->hdisp << 1) / 3) << 1;
-                                        svga->hblankstart = (svga->hblankstart << 1) / 3;
-                                        svga->hblank_end_val = ((svga->hblank_end_val << 1) / 3) << 1;
-                                        break;
-                                    default:
-                                        break;
-                                }
-                                break;
-
-                            default:
-                                break;
-                        }
+                        svga->dots_per_clock = (svga->dots_per_clock << 1) / 3;
                         break;
 
                     case S3_TRIO64:
                     case S3_TRIO32:
                         svga->hdisp /= 3;
-                        svga->hblankstart /= 3;
-                        svga->hblank_end_val /= 3;
+                        svga->dots_per_clock /= 3;
                         break;
 
                     default:
@@ -3969,7 +3904,8 @@ s3_recalctimings(svga_t *svga)
                             svga->hdisp = 640;
                     }
                 } else {
-                    if (s3->card_type == S3_MIROVIDEO40SV_ERGO_968 || s3->card_type == S3_PHOENIX_VISION968 || s3->card_type == S3_SPEA_MERCURY_P64V)
+                    if ((s3->card_type == S3_MIROVIDEO40SV_ERGO_968) ||
+                        (s3->card_type == S3_PHOENIX_VISION968) || (s3->card_type == S3_SPEA_MERCURY_P64V))
                         svga->hdisp = s3->width;
                 }
 #endif
@@ -3982,8 +3918,7 @@ s3_recalctimings(svga_t *svga)
                             case S3_PHOENIX_VISION868:
                             case S3_NUMBER9_9FX_531:
                                 svga->hdisp >>= 1;
-                                svga->hblankstart >>= 1;
-                                svga->hblank_end_val >>= 1;
+                                svga->dots_per_clock >>= 1;
                                 break;
                             default:
                                 break;
@@ -3996,8 +3931,7 @@ s3_recalctimings(svga_t *svga)
                                     case 800:
                                     case 1024:
                                         svga->hdisp >>= 1;
-                                        svga->hblankstart >>= 1;
-                                        svga->hblank_end_val >>= 1;
+                                        svga->dots_per_clock >>= 1;
                                         break;
                                     default:
                                         break;
@@ -4008,8 +3942,7 @@ s3_recalctimings(svga_t *svga)
                                     case 1280:
                                     case 1600:
                                         svga->hdisp <<= 1;
-                                        svga->hblankstart <<= 1;
-                                        svga->hblank_end_val <<= 1;
+                                        svga->dots_per_clock <<= 1;
                                         break;
                                     default:
                                         break;
@@ -4024,8 +3957,7 @@ s3_recalctimings(svga_t *svga)
                             case S3_NUMBER9_9FX_771:
                             case S3_PHOENIX_VISION968:
                                 svga->hdisp <<= 1;
-                                svga->hblankstart <<= 1;
-                                svga->hblank_end_val <<= 1;
+                                svga->dots_per_clock <<= 1;
                                 /* TODO: Is this still needed? */
                                 if (svga->hdisp == 832)
                                     svga->hdisp -= 32;
@@ -4036,8 +3968,7 @@ s3_recalctimings(svga_t *svga)
                                     case 1280:
                                     case 1600:
                                         svga->hdisp <<= 1;
-                                        svga->hblankstart <<= 1;
-                                        svga->hblank_end_val <<= 1;
+                                        svga->dots_per_clock <<= 1;
                                         break;
                                     default:
                                         break;
@@ -4105,7 +4036,8 @@ s3_recalctimings(svga_t *svga)
                 if (svga->crtc[0x31] & 0x08) {
                     svga->vram_display_mask = s3->vram_mask;
                     if (svga->bpp == 8) {
-                        svga->render = svga_render_8bpp_highres; /*Enhanced 4bpp mode, just like the 8bpp mode per spec.*/
+                        /*Enhanced 4bpp mode, just like the 8bpp mode per the spec. */
+                        svga->render = svga_render_8bpp_highres;
                         svga->rowoffset <<= 1;
                     }
                 }
@@ -4125,6 +4057,12 @@ s3_trio64v_recalctimings(svga_t *svga)
         svga->dots_per_clock = ((svga->seqregs[1] & 1) ? 16 : 18);
     }
 
+    if ((svga->crtc[0x33] & 0x20) ||((svga->crtc[0x67] & 0xc) == 0xc)) {
+        /* In this mode, the dots per clock are always 8 or 16, never 9 or 18. */
+        if (!svga->scrblank && svga->attr_palette_enable)
+            svga->dots_per_clock = (svga->seqregs[1] & 8) ? 16 : 8;
+    }
+
     svga->hdisp = svga->hdisp_old;
     if (svga->crtc[0x5d] & 0x01)
         svga->htotal |= 0x100;
@@ -4176,13 +4114,6 @@ s3_trio64v_recalctimings(svga_t *svga)
                             ((svga->crtc[3] >> 5) & 3) + 1;
         svga->hblank_end_val = ((svga->crtc[3] >> 5) & 3);
 
-        /* In this mode, the dots per clock are always 8 or 16, never 9 or 18. */
-        if (!svga->scrblank && svga->attr_palette_enable)
-            svga->dots_per_clock = (svga->seqregs[1] & 8) ? 16 : 8;
-
-        /* No overscan in this mode. */
-        svga->hblank_overscan = 0;
-
         svga->monitor->mon_overscan_y = 0;
         svga->monitor->mon_overscan_x = 0;
 
@@ -4197,6 +4128,7 @@ s3_trio64v_recalctimings(svga_t *svga)
                  and Vision968. */
         svga->hblank_end_val = (svga->crtc[3] & 0x1f) | (((svga->crtc[5] & 0x80) >> 7) << 5) |
                                (((svga->crtc[0x5d] & 0x08) >> 3) << 6);
+        svga->hblank_end_mask = 0x7f;
     }
 
     if ((svga->crtc[0x67] & 0xc) != 0xc) /*VGA mode*/
@@ -4220,20 +4152,17 @@ s3_trio64v_recalctimings(svga_t *svga)
                 case 15:
                     svga->render = svga_render_15bpp_highres;
                     svga->hdisp >>= 1;
-                    svga->hblankstart >>= 1;
-                    svga->hblank_end_val >>= 1;
+                    svga->dots_per_clock >>= 1;
                     break;
                 case 16:
                     svga->render = svga_render_16bpp_highres;
                     svga->hdisp >>= 1;
-                    svga->hblankstart >>= 1;
-                    svga->hblank_end_val >>= 1;
+                    svga->dots_per_clock >>= 1;
                     break;
                 case 24:
                     svga->render = svga_render_24bpp_highres;
                     svga->hdisp /= 3;
-                    svga->hblankstart >>= 1;
-                    svga->hblank_end_val /= 3;
+                    svga->dots_per_clock /= 3;
                     break;
                 case 32:
                     svga->render = svga_render_32bpp_highres;
diff --git a/src/video/vid_s3_virge.c b/src/video/vid_s3_virge.c
index a0bf98815..3184a1ccd 100644
--- a/src/video/vid_s3_virge.c
+++ b/src/video/vid_s3_virge.c
@@ -783,6 +783,12 @@ s3_virge_recalctimings(svga_t *svga)
         svga->dots_per_clock = ((svga->seqregs[1] & 1) ? 16 : 18);
     }
 
+    if ((svga->crtc[0x33] & 0x20) || ((svga->crtc[0x67] & 0xc) == 0xc)) {
+        /* In this mode, the dots per clock are always 8 or 16, never 9 or 18. */
+        if (!svga->scrblank && svga->attr_palette_enable)
+            svga->dots_per_clock = (svga->seqregs[1] & 8) ? 16 : 8;
+    }
+
     if (svga->crtc[0x5d] & 0x01)
         svga->htotal += 0x100;
     if (svga->crtc[0x5d] & 0x02) {
@@ -824,13 +830,6 @@ s3_virge_recalctimings(svga_t *svga)
                             ((svga->crtc[3] >> 5) & 3) + 1;
         svga->hblank_end_val = ((svga->crtc[3] >> 5) & 3);
 
-        /* In this mode, the dots per clock are always 8 or 16, never 9 or 18. */
-        if (!svga->scrblank && svga->attr_palette_enable)
-            svga->dots_per_clock = (svga->seqregs[1] & 8) ? 16 : 8;
-
-        /* No overscan in this mode. */
-        svga->hblank_overscan = 0;
-
         svga->monitor->mon_overscan_y = 0;
         svga->monitor->mon_overscan_x = 0;
 
@@ -839,8 +838,9 @@ s3_virge_recalctimings(svga_t *svga)
     } else {
         svga->hblankstart    = (((svga->crtc[0x5d] & 0x04) >> 2) << 8) + svga->crtc[2] + 1;
 
-        svga->hblank_end_val = (svga->crtc[3] & 0x1f) | (((svga->crtc[5] & 0x80) >> 7) << 5) |
-                               (((svga->crtc[0x5d] & 0x08) >> 3) << 6);
+        svga->hblank_end_val  = (svga->crtc[3] & 0x1f) | (((svga->crtc[5] & 0x80) >> 7) << 5) |
+                                (((svga->crtc[0x5d] & 0x08) >> 3) << 6);
+        svga->hblank_end_mask = 0x7f;
     }
 
     if ((svga->crtc[0x67] & 0xc) != 0xc) /*VGA mode*/
diff --git a/src/video/vid_svga.c b/src/video/vid_svga.c
index 692bfef27..a1ab605ea 100644
--- a/src/video/vid_svga.c
+++ b/src/video/vid_svga.c
@@ -641,10 +641,17 @@ svga_recalctimings(svga_t *svga)
     svga->render     = svga_render_blank;
     if (!svga->scrblank && (svga->crtc[0x17] & 0x80) && svga->attr_palette_enable) {
         /* TODO: In case of bug reports, disable 9-dots-wide character clocks in graphics modes. */
-        if (svga->seqregs[1] & 8)
-            svga->hdisp *= (svga->seqregs[1] & 1) ? 16 : 18;
-        else
-            svga->hdisp *= (svga->seqregs[1] & 1) ? 8 : 9;
+        if (!(svga->gdcreg[6] & 1) && !(svga->attrregs[0x10] & 1)) {
+            if (svga->seqregs[1] & 8)
+                svga->hdisp *= (svga->seqregs[1] & 1) ? 16 : 18;
+            else
+                svga->hdisp *= (svga->seqregs[1] & 1) ? 8 : 9;
+        } else {
+            if (svga->seqregs[1] & 8)
+                svga->hdisp *= 16;
+            else
+                svga->hdisp *= 8;
+        }
 
         if (!(svga->gdcreg[6] & 1) && !(svga->attrregs[0x10] & 1)) { /*Text mode*/
             if (svga->seqregs[1] & 8) {                              /*40 column*/
@@ -740,19 +747,24 @@ svga_recalctimings(svga_t *svga)
 
     svga->hblankstart    = svga->crtc[2] + 1;
     svga->hblank_end_val = (svga->crtc[3] & 0x1f) | ((svga->crtc[5] & 0x80) ? 0x20 : 0x00);
+    svga->hblank_end_mask = 0x0000003f;
 
     svga_log("htotal = %i, hblankstart = %i, hblank_end_val = %02X\n",
              svga->htotal, svga->hblankstart, svga->hblank_end_val);
 
-    svga->hblank_end_len  = 0x00000040;
-    svga->hblank_overscan = 1;
-
     if (!svga->scrblank && svga->attr_palette_enable) {
         /* TODO: In case of bug reports, disable 9-dots-wide character clocks in graphics modes. */
-        if (svga->seqregs[1] & 8)
-            svga->dots_per_clock = ((svga->seqregs[1] & 1) ? 16 : 18);
-        else
-            svga->dots_per_clock = ((svga->seqregs[1] & 1) ? 8 : 9);
+        if (!(svga->gdcreg[6] & 1) && !(svga->attrregs[0x10] & 1)) {
+            if (svga->seqregs[1] & 8)
+                svga->dots_per_clock = ((svga->seqregs[1] & 1) ? 16 : 18);
+            else
+                svga->dots_per_clock = ((svga->seqregs[1] & 1) ? 8 : 9);
+        } else {
+            if (svga->seqregs[1] & 8)
+                svga->dots_per_clock = 16;
+            else
+                svga->dots_per_clock = 8;
+        }
     } else
         svga->dots_per_clock = 1;
 
@@ -768,18 +780,31 @@ svga_recalctimings(svga_t *svga)
         xga_recalctimings(svga);
 
     if (!svga->hoverride) {
-        svga->hblankend = (svga->hblankstart & ~(svga->hblank_end_len - 1)) | svga->hblank_end_val;
-        if (svga->hblankend <= svga->hblankstart)
-            svga->hblankend += svga->hblank_end_len;
-        svga->hblankend += svga->hblank_ext;
-
+        uint32_t dot = svga->hblankstart;
+        uint32_t adj_dot = svga->hblankstart;
+        /* Verified with both the Voodoo 3 and the S3 cards: compare 7 bits if bit 7 is set,
+           otherwise compare 6 bits. */
+        uint32_t eff_mask = (svga->hblank_end_val & ~0x0000003f) ? svga->hblank_end_mask : 0x0000003f;
         svga->hblank_sub = 0;
-        if (svga->hblankend > svga->htotal) {
-            svga->hblankend &= (svga->hblank_end_len - 1);
-            svga->hblank_sub = svga->hblankend + svga->hblank_overscan;
 
-            svga->hdisp -= (svga->hblank_sub * svga->dots_per_clock);
+        svga_log("Blank: %04i-%04i, Total: %04i, Mask: %02X\n", svga->hblankstart, svga->hblank_end_val,
+                 svga->htotal, eff_mask);
+
+        while (1) {
+            if (dot == svga->htotal)
+                dot = 0;
+
+            if (adj_dot >= svga->htotal)
+                svga->hblank_sub++;
+
+            if ((dot & eff_mask) == (svga->hblank_end_val & eff_mask))
+                break;
+
+            dot++;
+            adj_dot++;
         }
+
+        svga->hdisp -= (svga->hblank_sub * svga->dots_per_clock);
     }
 
     if (svga->hdisp >= 2048)
@@ -1278,7 +1303,6 @@ svga_init(const device_t *info, svga_t *svga, void *priv, int memsize,
     svga->ramdac_type = RAMDAC_6BIT;
 
     svga->map8            = svga->pallook;
-    svga->hblank_overscan = 1; /* Do at least 1 character of overscan after horizontal blanking. */
 
     return 0;
 }
diff --git a/src/video/vid_voodoo_banshee.c b/src/video/vid_voodoo_banshee.c
index cf8cc154c..9fec8c073 100644
--- a/src/video/vid_voodoo_banshee.c
+++ b/src/video/vid_voodoo_banshee.c
@@ -556,17 +556,20 @@ banshee_recalctimings(svga_t *svga)
      if (banshee->vidProcCfg & VIDPROCCFG_VIDPROC_ENABLE) {
         /* Video processing mode - assume timings akin to Cirrus' special blanking mode,
            that is, no overscan and relying on display end to blank. */
-        svga->hblankstart    = svga->crtc[1] + ((svga->crtc[3] >> 5) & 3) +
-                               (((svga->crtc[0x1a] & 0x04) >> 2) << 8) + 1;
+        if (banshee->vgaInit0 & 0x40) {
+            svga->hblankstart     = svga->crtc[1] + ((svga->crtc[3] >> 5) & 3) +
+                                   (((svga->crtc[0x1a] & 0x04) >> 2) << 8) + 1;
+            svga->hblank_end_mask = 0x0000007f;
+        } else {
+            svga->hblankstart     = svga->crtc[1] + ((svga->crtc[3] >> 5) & 3) + 1;
+            svga->hblank_end_mask = 0x0000003f;
+        }
         svga->hblank_end_val = ((svga->crtc[3] >> 5) & 3);
 
         /* In this mode, the dots per clock are always 8 or 16, never 9 or 18. */
         if (!svga->scrblank && svga->attr_palette_enable)
             svga->dots_per_clock = (svga->seqregs[1] & 8) ? 16 : 8;
 
-        /* No overscan in this mode. */
-        svga->hblank_overscan = 0;
-
         svga->monitor->mon_overscan_y = 0;
         svga->monitor->mon_overscan_x = 0;
 
@@ -575,9 +578,16 @@ banshee_recalctimings(svga_t *svga)
 
         svga->linedbl     = 0;
      } else {
-        svga->hblankstart    = (((svga->crtc[0x1a] & 0x10) >> 4) << 8) + svga->crtc[2] + 1;
-        svga->hblank_end_val = (svga->crtc[3] & 0x1f) | (((svga->crtc[5] & 0x80) >> 7) << 5) |
-                               (((svga->crtc[0x1a] & 0x20) >> 5) << 6);
+        if (banshee->vgaInit0 & 0x40) {
+            svga->hblankstart     = (((svga->crtc[0x1a] & 0x10) >> 4) << 8) + svga->crtc[2] + 1;
+            svga->hblank_end_val  = (svga->crtc[3] & 0x1f) | (((svga->crtc[5] & 0x80) >> 7) << 5) |
+                                    (((svga->crtc[0x1a] & 0x20) >> 5) << 6);
+            svga->hblank_end_mask = 0x0000007f;
+        } else {
+            svga->hblankstart     =  svga->crtc[2] + 1;
+            svga->hblank_end_val  =  (svga->crtc[3] & 0x1f) | (((svga->crtc[5] & 0x80) >> 7) << 5);
+            svga->hblank_end_mask =  0x0000003f;
+        }
     }
 
     /*6 R/W Vertical Retrace Start bit 10 0x10
@@ -642,9 +652,10 @@ banshee_recalctimings(svga_t *svga)
 
         if (banshee->vidProcCfg & VIDPROCCFG_2X_MODE) {
             svga->hdisp *= 2;
-            svga->htotal *= 2;
-            svga->hblankstart *= 2;
-            svga->hblank_end_val *= 2;
+            // svga->htotal *= 2;
+            // svga->hblankstart *= 2;
+            // svga->hblank_end_val *= 2;
+            svga->dots_per_clock *= 2;
         }
 
         svga->interlace = !!(banshee->vidProcCfg & VIDPROCCFG_INTERLACE);