diff --git a/src/video/vid_s3_virge.c b/src/video/vid_s3_virge.c
index 66682b440..3719d2591 100644
--- a/src/video/vid_s3_virge.c
+++ b/src/video/vid_s3_virge.c
@@ -867,7 +867,7 @@ s3_virge_recalctimings(svga_t *svga)
         video_force_resize_set_monitor(1, svga->monitor_index);
     }
 
-    if (((svga->crtc[0x67] & 0xc) != 0xc) || (virge->chip >= S3_VIRGEGX2)) { /*VGA mode*/
+    if ((svga->crtc[0x67] & 0xc) != 0xc) { /*VGA mode*/
         svga->ma_latch |= (virge->ma_ext << 16);
         if (svga->crtc[0x51] & 0x30)
             svga->rowoffset |= (svga->crtc[0x51] & 0x30) << 4;
@@ -898,7 +898,7 @@ s3_virge_recalctimings(svga_t *svga)
             case 24:
                 svga->render = svga_render_24bpp_highres;
                 if ((virge->chip != S3_VIRGEVX) && (virge->chip < S3_VIRGEGX2))
-                    svga->rowoffset = (svga->rowoffset * 3) / 4; /*Hack*/
+                    svga->rowoffset = (svga->rowoffset * 3) >> 2; /*Hack*/
                 break;
             case 32:
                 svga->render = svga_render_32bpp_highres;
@@ -910,37 +910,32 @@ s3_virge_recalctimings(svga_t *svga)
 
         svga->vram_display_mask = (!(svga->crtc[0x31] & 0x08) &&
                                   (svga->crtc[0x32] & 0x40)) ? 0x3ffff : virge->vram_mask;
-
-        svga->overlay.ena       = 0;
-
-        if (virge->chip >= S3_VIRGEGX2 && (svga->crtc[0x67] & 0xc) == 0xc) {
-            /* ViRGE/GX2 and later does not use primary stream registers. */
-            svga->overlay.x         = virge->streams.sec_x;
-            svga->overlay.y         = virge->streams.sec_y;
-            svga->overlay.cur_ysize = virge->streams.sec_h;
-
-            if (virge->streams.buffer_ctrl & 2)
-                svga->overlay.addr = virge->streams.sec_fb1;
-            else
-                svga->overlay.addr = virge->streams.sec_fb0;
-
-            svga->overlay.ena       = (svga->overlay.x >= 0) && !!(virge->streams.blend_ctrl & 0x20);
-            svga->overlay.v_acc     = virge->streams.dda_vert_accumulator;
-            svga->rowoffset         = virge->streams.pri_stride >> 3;
-            svga->vram_display_mask = virge->vram_mask;
-        }
     } else { /*Streams mode*/
-        if (virge->streams.buffer_ctrl & 1)
-            svga->ma_latch = virge->streams.pri_fb1 >> 2;
-        else
-            svga->ma_latch = virge->streams.pri_fb0 >> 2;
+        if (virge->chip < S3_VIRGEGX2) {
+            if (virge->streams.buffer_ctrl & 1)
+                svga->ma_latch = virge->streams.pri_fb1 >> 2;
+            else
+                svga->ma_latch = virge->streams.pri_fb0 >> 2;
 
-        svga->hdisp = virge->streams.pri_w + 1;
-        if (virge->streams.pri_h < svga->dispend)
-            svga->dispend = virge->streams.pri_h;
+            svga->hdisp = virge->streams.pri_w + 1;
+            if (virge->streams.pri_h < svga->dispend)
+                svga->dispend = virge->streams.pri_h;
+
+            svga->overlay.x = virge->streams.sec_x - virge->streams.pri_x;
+            svga->overlay.y = virge->streams.sec_y - virge->streams.pri_y;
+        } else {
+            svga->ma_latch |= (virge->ma_ext << 16);
+            if (svga->crtc[0x51] & 0x30)
+                svga->rowoffset |= (svga->crtc[0x51] & 0x30) << 4;
+            else if (svga->crtc[0x43] & 0x04)
+                svga->rowoffset |= 0x100;
+            if (!svga->rowoffset)
+                svga->rowoffset = 256;
+
+            svga->overlay.x = virge->streams.sec_x;
+            svga->overlay.y = virge->streams.sec_y;
+        }
 
-        svga->overlay.x = virge->streams.sec_x - virge->streams.pri_x;
-        svga->overlay.y = virge->streams.sec_y - virge->streams.pri_y;
         svga->overlay.cur_ysize = virge->streams.sec_h;
 
         if (virge->streams.buffer_ctrl & 2)
@@ -949,35 +944,60 @@ s3_virge_recalctimings(svga_t *svga)
             svga->overlay.addr = virge->streams.sec_fb0;
 
         svga->overlay.ena = (svga->overlay.x >= 0);
+        svga->overlay.h_acc = virge->streams.dda_horiz_accumulator;
         svga->overlay.v_acc = virge->streams.dda_vert_accumulator;
 
-        svga->rowoffset = virge->streams.pri_stride >> 3;
+        if (virge->chip < S3_VIRGEGX2)
+            svga->rowoffset = virge->streams.pri_stride >> 3;
 
         if (virge->chip <= S3_VIRGEDX && svga->overlay.ena) {
             svga->overlay.ena = (((virge->streams.blend_ctrl >> 24) & 7) == 0b000) ||
                                 (((virge->streams.blend_ctrl >> 24) & 7) == 0b101);
-        } else if (virge->chip == S3_VIRGEGX2 && svga->overlay.ena) {
+        } else if (virge->chip >= S3_VIRGEGX2 && svga->overlay.ena) {
             /* 0x20 = Secondary Stream enabled */
             /* 0x2000 = Primary Stream enabled */
             svga->overlay.ena = !!(virge->streams.blend_ctrl & 0x20);
         }
 
-        switch ((virge->streams.pri_ctrl >> 24) & 0x7) {
-            case 0: /*RGB-8 (CLUT)*/
-                svga->render = svga_render_8bpp_highres;
-                break;
-            case 3: /*KRGB-16 (1.5.5.5)*/
-                svga->render = svga_render_15bpp_highres;
-                break;
-            case 5: /*RGB-16 (5.6.5)*/
-                svga->render = svga_render_16bpp_highres;
-                break;
-            case 6: /*RGB-24 (8.8.8)*/
-                svga->render = svga_render_24bpp_highres;
-                break;
-            case 7: /*XRGB-32 (X.8.8.8)*/
-                svga->render = svga_render_32bpp_highres;
-                break;
+        if (virge->chip >= S3_VIRGEGX2) {
+            switch (svga->bpp) {
+                case 8:
+                    svga->render = svga_render_8bpp_highres;
+                    break;
+                case 15:
+                    svga->render = svga_render_15bpp_highres;
+                    break;
+                case 16:
+                    svga->render = svga_render_16bpp_highres;
+                    break;
+                case 24:
+                    svga->render = svga_render_24bpp_highres;
+                    break;
+                case 32:
+                    svga->render = svga_render_32bpp_highres;
+                    break;
+
+                default:
+                    break;
+            }
+        } else {
+            switch ((virge->streams.pri_ctrl >> 24) & 0x7) {
+                case 0: /*RGB-8 (CLUT)*/
+                    svga->render = svga_render_8bpp_highres;
+                    break;
+                case 3: /*KRGB-16 (1.5.5.5)*/
+                    svga->render = svga_render_15bpp_highres;
+                    break;
+                case 5: /*RGB-16 (5.6.5)*/
+                    svga->render = svga_render_16bpp_highres;
+                    break;
+                case 6: /*RGB-24 (8.8.8)*/
+                    svga->render = svga_render_24bpp_highres;
+                    break;
+                case 7: /*XRGB-32 (X.8.8.8)*/
+                    svga->render = svga_render_32bpp_highres;
+                    break;
+            }
         }
         svga->vram_display_mask = virge->vram_mask;
     }
@@ -990,29 +1010,6 @@ s3_virge_recalctimings(svga_t *svga)
         svga->render = svga_render_2bpp_s3_highres;
 }
 
-static void
-s3_virge_update_buffer(virge_t *virge)
-{
-    svga_t *svga = &virge->svga;
-
-    if ((svga->crtc[0x67] & 0xc) != 0xc)
-        return;
-
-    if (virge->chip < S3_VIRGEGX2) {
-        if (virge->streams.buffer_ctrl & 1)
-            svga->ma_latch = virge->streams.pri_fb1 >> 2;
-        else
-            svga->ma_latch = virge->streams.pri_fb0 >> 2;
-    }
-
-    if (virge->streams.buffer_ctrl & 2)
-        svga->overlay.addr = virge->streams.sec_fb1;
-    else
-        svga->overlay.addr = virge->streams.sec_fb0;
-
-    svga->rowoffset = virge->streams.pri_stride >> 3;
-}
-
 static void
 s3_virge_updatemapping(virge_t *virge) {
     svga_t *svga = &virge->svga;
@@ -1844,39 +1841,46 @@ s3_virge_queue(virge_t *virge, uint32_t addr, uint32_t val, uint32_t type)
 }
 
 static void
-s3_virge_mmio_write(uint32_t addr, uint8_t val, void *priv) {
+s3_virge_mmio_write(uint32_t addr, uint8_t val, void *priv)
+{
     virge_t *virge = (virge_t *) priv;
 
     if ((addr & 0xffff) < 0x8000)
         s3_virge_queue(virge, addr, val, FIFO_WRITE_BYTE);
-    else switch (addr & 0xffff) {
-        case 0x83b0 ... 0x83df:
-            s3_virge_out(addr & 0x3ff, val, priv);
-            break;
+    else {
+        switch (addr & 0xffff) {
+            default:
+            case 0x83b0 ... 0x83df:
+                s3_virge_out(addr & 0x3ff, val, priv);
+                break;
 
-        case 0xff20:
-            virge->serialport = val;
-            i2c_gpio_set(virge->i2c, !!(val & SERIAL_PORT_SCW), !!(val & SERIAL_PORT_SDW));
-            break;
+            case 0xff20:
+                virge->serialport = val;
+                i2c_gpio_set(virge->i2c, !!(val & SERIAL_PORT_SCW), !!(val & SERIAL_PORT_SDW));
+                break;
+        }
     }
 }
 
 static void
-s3_virge_mmio_write_w(uint32_t addr, uint16_t val, void *priv) {
+s3_virge_mmio_write_w(uint32_t addr, uint16_t val, void *priv)
+{
     virge_t *virge = (virge_t *) priv;
 
     if ((addr & 0xfffe) < 0x8000)
         s3_virge_queue(virge, addr, val, FIFO_WRITE_WORD);
-    else  switch (addr & 0xfffe) {
-        default:
-        case 0x83d4:
-            s3_virge_mmio_write(addr, val, priv);
-            s3_virge_mmio_write(addr + 1, val >> 8, priv);
-            break;
+    else {
+        switch (addr & 0xfffe) {
+            default:
+            case 0x83d4:
+                s3_virge_mmio_write(addr, val, priv);
+                s3_virge_mmio_write(addr + 1, val >> 8, priv);
+                break;
 
-        case 0xff20:
-            s3_virge_mmio_write(addr, val, priv);
-            break;
+            case 0xff20:
+                s3_virge_mmio_write(addr, val, priv);
+                break;
+        }
     }
 }
 
@@ -1902,8 +1906,9 @@ s3_virge_mmio_write_l(uint32_t addr, uint32_t val, void *priv) {
             case 0x8190:
                 virge->streams.sec_ctrl = val;
                 virge->streams.dda_horiz_accumulator = val & 0xfff;
-                if (val & (1 << 11))
-                    virge->streams.dda_horiz_accumulator |= 0xfffff800;
+                if (val & 0x1000)
+                    virge->streams.dda_horiz_accumulator |= ~0xfff;
+
                 virge->streams.sdif = (val >> 24) & 7;
                 break;
             case 0x8194:
@@ -1912,50 +1917,56 @@ s3_virge_mmio_write_l(uint32_t addr, uint32_t val, void *priv) {
             case 0x8198:
                 virge->streams.sec_filter = val;
                 virge->streams.k1_horiz_scale = val & 0x7ff;
-                if (val & (1 << 10))
-                    virge->streams.k1_horiz_scale |= 0xfffff800;
+                if (val & 0x800)
+                    virge->streams.k1_horiz_scale |= ~0x7ff;
+
                 virge->streams.k2_horiz_scale = (val >> 16) & 0x7ff;
-                if ((val >> 16) & (1 << 10))
-                    virge->streams.k2_horiz_scale |= 0xfffff800;
+                if ((val >> 16) & 0x800)
+                    virge->streams.k2_horiz_scale |= ~0x7ff;
+
+                svga_recalctimings(svga);
+                svga->fullchange = changeframecount;
                 break;
             case 0x81a0:
                 virge->streams.blend_ctrl = val;
+                svga_recalctimings(svga);
+                svga->fullchange = changeframecount;
                 break;
             case 0x81c0:
                 virge->streams.pri_fb0 = val & ((virge->memory_size == 8) ?
                                                 (val & 0x7fffff) : (val & 0x3fffff));
-                s3_virge_update_buffer(virge);
+                svga_recalctimings(svga);
                 svga->fullchange = changeframecount;
                 break;
             case 0x81c4:
                 virge->streams.pri_fb1 = ((virge->memory_size == 8) ?
                                           (val & 0x7fffff) : (val & 0x3fffff));
-                s3_virge_update_buffer(virge);
+                svga_recalctimings(svga);
                 svga->fullchange = changeframecount;
                 break;
             case 0x81c8:
                 virge->streams.pri_stride = val & 0xfff;
-                s3_virge_update_buffer(virge);
+                svga_recalctimings(svga);
                 svga->fullchange = changeframecount;
                 break;
             case 0x81cc:
                 virge->streams.buffer_ctrl = val;
-                s3_virge_update_buffer(virge);
+                svga_recalctimings(svga);
                 svga->fullchange = changeframecount;
                 break;
             case 0x81d0:
                 virge->streams.sec_fb0 = val;
-                s3_virge_update_buffer(virge);
+                svga_recalctimings(svga);
                 svga->fullchange = changeframecount;
                 break;
             case 0x81d4:
                 virge->streams.sec_fb1 = val;
-                s3_virge_update_buffer(virge);
+                svga_recalctimings(svga);
                 svga->fullchange = changeframecount;
                 break;
             case 0x81d8:
                 virge->streams.sec_stride = val;
-                s3_virge_update_buffer(virge);
+                svga_recalctimings(svga);
                 svga->fullchange = changeframecount;
                 break;
             case 0x81dc:
@@ -1963,18 +1974,21 @@ s3_virge_mmio_write_l(uint32_t addr, uint32_t val, void *priv) {
                 break;
             case 0x81e0:
                 virge->streams.k1_vert_scale = val & 0x7ff;
-                if (val & (1 << 10))
-                    virge->streams.k1_vert_scale |= 0xfffff800;
+                if (val & 0x800)
+                    virge->streams.k1_vert_scale |= ~0x7ff;
                 break;
             case 0x81e4:
                 virge->streams.k2_vert_scale = val & 0x7ff;
-                if (val & (1 << 10))
-                    virge->streams.k2_vert_scale |= 0xfffff800;
+                if (val & 0x800)
+                    virge->streams.k2_vert_scale |= ~0x7ff;
                 break;
             case 0x81e8:
                 virge->streams.dda_vert_accumulator = val & 0xfff;
-                if (val & (1 << 11))
-                    virge->streams.dda_vert_accumulator |= 0xfffff800;
+                if (val & 0x1000)
+                    virge->streams.dda_vert_accumulator |= ~0xfff;
+
+                svga_recalctimings(svga);
+                svga->fullchange = changeframecount;
                 break;
             case 0x81ec:
                 virge->streams.fifo_ctrl = val;
@@ -3968,10 +3982,10 @@ static void s3_virge_hwcursor_draw(svga_t *svga, int displine) {
     } while (0)
 
 static void
-s3_virge_overlay_draw(svga_t *svga, int displine) {
+s3_virge_overlay_draw(svga_t *svga, int displine)
+{
     virge_t  *virge  = (virge_t *) svga->priv;
-    int       offset = (virge->streams.sec_x - virge->streams.pri_x) + 1;
-    int       h_acc  = virge->streams.dda_horiz_accumulator;
+    int       offset;
     int       r[8];
     int       g[8];
     int       b[8];
@@ -3982,11 +3996,19 @@ s3_virge_overlay_draw(svga_t *svga, int displine) {
     uint32_t *p;
     uint8_t  *src = &svga->vram[svga->overlay_latch.addr];
 
+    if (virge->chip < S3_VIRGEGX2)
+        offset = (virge->streams.sec_x - virge->streams.pri_x) + 1;
+    else
+        offset = virge->streams.sec_x + 1;
+
     p = &((uint32_t *)buffer32->line[displine])[offset + svga->x_add];
 
-    if ((offset + virge->streams.sec_w) > virge->streams.pri_w)
-        x_size = (virge->streams.pri_w - virge->streams.sec_x) + 1;
-    else
+    if (virge->chip < S3_VIRGEGX2) {
+        if ((offset + virge->streams.sec_w) > virge->streams.pri_w)
+            x_size = (virge->streams.pri_w - virge->streams.sec_x) + 1;
+        else
+            x_size = virge->streams.sec_w + 1;
+    } else
         x_size = virge->streams.sec_w + 1;
 
     OVERLAY_SAMPLE();
@@ -3994,13 +4016,14 @@ s3_virge_overlay_draw(svga_t *svga, int displine) {
     for (x = 0; x < x_size; x++) {
         *p++ = r[x_read] | (g[x_read] << 8) | (b[x_read] << 16);
 
-        h_acc += virge->streams.k1_horiz_scale;
-        if (h_acc >= 0) {
+        svga->overlay_latch.h_acc += virge->streams.k1_horiz_scale;
+        if (svga->overlay_latch.h_acc >= 0) {
             if ((x_read ^ (x_read + 1)) & ~3)
                 OVERLAY_SAMPLE();
+
             x_read = (x_read + 1) & 7;
 
-            h_acc += (virge->streams.k2_horiz_scale - virge->streams.k1_horiz_scale);
+            svga->overlay_latch.h_acc += (virge->streams.k2_horiz_scale - virge->streams.k1_horiz_scale);
         }
     }