diff --git a/src/video/vid_cl54xx.c b/src/video/vid_cl54xx.c
index 225810974..74af8b4a1 100644
--- a/src/video/vid_cl54xx.c
+++ b/src/video/vid_cl54xx.c
@@ -1828,6 +1828,28 @@ gd54xx_recalctimings(svga_t *svga)
     }
 
     svga->vram_display_mask = (svga->crtc[0x1b] & 2) ? gd54xx->vram_mask : 0x3ffff;
+
+    pclog("svga->crtc[0x1a] = %02X\n", svga->crtc[0x1a]);
+    pclog("svga->crtc[0x1b] = %02X\n", svga->crtc[0x1b]);
+    pclog("svga->crtc[0x1c] = %02X\n", svga->crtc[0x1c]);
+
+    if (svga->crtc[0x27] >= CIRRUS_ID_CLGD5430)
+	svga->htotal += ((svga->crtc[0x1c] >> 3) & 0x07);
+
+    if (svga->crtc[0x1b] & ((svga->crtc[0x27] >= CIRRUS_ID_CLGD5424) ? 0xa0 : 0x20)) {
+	/* Special blanking mode: the blank start and end become components of the window generator,
+				  and the actual blanking comes from the display enable signal. */
+	/* Start blanking at the first character clock after the last active one. */
+	svga->hblankstart = svga->crtc[1] + 1;
+	svga->hblank_end_val = (svga->htotal + 6) & 0x3f;
+	/* 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;
+	/* Also make sure vertical blanking starts on display end. */
+	svga->vblankstart = svga->dispend;
+    }
 }
 
 static void
diff --git a/src/video/vid_et4000.c b/src/video/vid_et4000.c
index a97d65cdb..b7362dd00 100644
--- a/src/video/vid_et4000.c
+++ b/src/video/vid_et4000.c
@@ -55,17 +55,19 @@
 #include <86box/plat_fallthrough.h>
 #include <86box/plat_unused.h>
 
+#define ET4000_TYPE_TC6058AF 0 /* ISA ET4000AX (TC6058AF) */
 #define ET4000_TYPE_ISA      1 /* ISA ET4000AX */
 #define ET4000_TYPE_MCA      2 /* MCA ET4000AX */
 #define ET4000_TYPE_KOREAN   3 /* Korean ET4000 */
 #define ET4000_TYPE_TRIGEM   4 /* Trigem 286M ET4000 */
 #define ET4000_TYPE_KASAN    5 /* Kasan ET4000 */
 
-#define BIOS_ROM_PATH        "roms/video/et4000/ET4000.BIN"
-#define KOREAN_BIOS_ROM_PATH "roms/video/et4000/tgkorvga.bin"
-#define KOREAN_FONT_ROM_PATH "roms/video/et4000/tg_ksc5601.rom"
-#define KASAN_BIOS_ROM_PATH  "roms/video/et4000/et4000_kasan16.bin"
-#define KASAN_FONT_ROM_PATH  "roms/video/et4000/kasan_ksc5601.rom"
+#define BIOS_ROM_PATH          "roms/video/et4000/ET4000.BIN"
+#define TC6058AF_BIOS_ROM_PATH "roms/video/et4000/Tseng_Labs_VGA-4000_BIOS_V1.1.bin"
+#define KOREAN_BIOS_ROM_PATH   "roms/video/et4000/tgkorvga.bin"
+#define KOREAN_FONT_ROM_PATH   "roms/video/et4000/tg_ksc5601.rom"
+#define KASAN_BIOS_ROM_PATH    "roms/video/et4000/et4000_kasan16.bin"
+#define KASAN_FONT_ROM_PATH    "roms/video/et4000/kasan_ksc5601.rom"
 
 typedef struct {
     const char *name;
@@ -115,6 +117,7 @@ et4000_in(uint16_t addr, void *priv)
 {
     et4000_t *dev  = (et4000_t *) priv;
     svga_t   *svga = &dev->svga;
+    uint8_t   ret;
 
     if (((addr & 0xfff0) == 0x3d0 || (addr & 0xfff0) == 0x3b0) && !(svga->miscout & 1))
         addr ^= 0x60;
@@ -138,7 +141,8 @@ et4000_in(uint16_t addr, void *priv)
         case 0x3c7:
         case 0x3c8:
         case 0x3c9:
-            return sc1502x_ramdac_in(addr, svga->ramdac, svga);
+            if (dev->type >= ET4000_TYPE_ISA)
+                return sc1502x_ramdac_in(addr, svga->ramdac, svga);
 
         case 0x3cd: /*Banking*/
             return dev->banking;
@@ -149,6 +153,26 @@ et4000_in(uint16_t addr, void *priv)
         case 0x3d5:
             return svga->crtc[svga->crtcreg];
 
+        case 0x3da:
+            svga->attrff = 0;
+
+            if (svga->cgastat & 0x01)
+                svga->cgastat &= ~0x30;
+            else
+                svga->cgastat ^= 0x30;
+
+            ret = svga->cgastat;
+
+            if ((svga->fcr & 0x08) && svga->dispon)
+                ret |= 0x08;
+
+            if (ret & 0x08)
+                ret &= 0x7f;
+            else
+                ret |= 0x80;
+
+            return ret;
+
         default:
             break;
     }
@@ -225,12 +249,33 @@ et4000_out(uint16_t addr, uint8_t val, void *priv)
         addr ^= 0x60;
 
     switch (addr) {
+        case 0x3c5:
+            if (svga->seqaddr == 4) {
+                svga->seqregs[4] = val;
+
+                svga->chain2_write = !(val & 4);
+                svga->chain4       = (svga->chain4 & ~8) | (val & 8);
+                svga->fast         = (svga->gdcreg[8] == 0xff && !(svga->gdcreg[3] & 0x18) && !svga->gdcreg[1]) && svga->chain4 && !(svga->adv_flags & FLAG_ADDR_BY8);
+                return;
+            } else if (svga->seqaddr == 0x0e) {
+                svga->seqregs[0x0e] = val;
+                svga->chain4 &= ~0x02;
+                if (svga->gdcreg[5] & 0x40)
+                    svga->chain4 |= (svga->seqregs[0x0e] & 0x02);
+                svga_recalctimings(svga);
+                return;
+            }
+            break;
+
         case 0x3c6:
         case 0x3c7:
         case 0x3c8:
         case 0x3c9:
-            sc1502x_ramdac_out(addr, val, svga->ramdac, svga);
-            return;
+            if (dev->type >= ET4000_TYPE_ISA) {
+                sc1502x_ramdac_out(addr, val, svga->ramdac, svga);
+                return;
+            }
+            break;
 
         case 0x3cd: /*Banking*/
             if (!(svga->crtc[0x36] & 0x10) && !(svga->gdcreg[6] & 0x08)) {
@@ -241,7 +286,11 @@ et4000_out(uint16_t addr, uint8_t val, void *priv)
             return;
 
         case 0x3cf:
-            if ((svga->gdcaddr & 15) == 6) {
+            if ((svga->gdcaddr & 15) == 5) {
+                svga->chain4 &= ~0x02;
+                if (val & 0x40)
+                    svga->chain4 |= (svga->seqregs[0x0e] & 0x02);
+            } else if ((svga->gdcaddr & 15) == 6) {
                 if (!(svga->crtc[0x36] & 0x10) && !(val & 0x08)) {
                     svga->write_bank = (dev->banking & 0x0f) * 0x10000;
                     svga->read_bank  = ((dev->banking >> 4) & 0x0f) * 0x10000;
@@ -418,7 +467,8 @@ et4000_kasan_out(uint16_t addr, uint8_t val, void *priv)
                     break;
                 case 1:
                 case 2:
-                    et4000->kasan_cfg_regs[et4000->kasan_cfg_index - 0xF0] = val;
+                    if ((et4000->kasan_cfg_index - 0xF0) <= 16)
+                        et4000->kasan_cfg_regs[et4000->kasan_cfg_index - 0xF0] = val;
                     io_removehandler(et4000->kasan_access_addr, 0x0008, et4000_kasan_in, NULL, NULL, et4000_kasan_out, NULL, NULL, et4000);
                     et4000->kasan_access_addr = (et4000->kasan_cfg_regs[2] << 8) | et4000->kasan_cfg_regs[1];
                     io_sethandler(et4000->kasan_access_addr, 0x0008, et4000_kasan_in, NULL, NULL, et4000_kasan_out, NULL, NULL, et4000);
@@ -465,7 +515,8 @@ et4000_kasan_out(uint16_t addr, uint8_t val, void *priv)
             case 4:
             case 5:
                 if (et4000->kasan_cfg_regs[0] & 1) {
-                    et4000->kasan_font_data[addr - (((et4000->kasan_cfg_regs[2] << 8) | (et4000->kasan_cfg_regs[1])) + 3)] = val;
+                    if ((addr - (((et4000->kasan_cfg_regs[2] << 8) | (et4000->kasan_cfg_regs[1])) + 3)) <= 4)
+                        et4000->kasan_font_data[addr - (((et4000->kasan_cfg_regs[2] << 8) | (et4000->kasan_cfg_regs[1])) + 3)] = val;
                 }
                 break;
             case 6:
@@ -607,6 +658,19 @@ et4000_recalctimings(svga_t *svga)
             }
         }
     }
+
+    if ((svga->seqregs[0x0e] & 0x02) && ((svga->gdcreg[5] & 0x60) >= 0x40)) {
+        svga->ma_latch <<= (1 << 0);
+        svga->rowoffset <<= (1 << 0);
+        svga->render = svga_render_8bpp_highres;
+    }
+
+    if (dev->type == ET4000_TYPE_TC6058AF) {
+        if (svga->render == svga_render_8bpp_lowres)
+            svga->render = svga_render_8bpp_tseng_lowres;
+        else if (svga->render == svga_render_8bpp_highres)
+            svga->render = svga_render_8bpp_tseng_highres;
+    }
 }
 
 static void
@@ -666,6 +730,7 @@ et4000_init(const device_t *info)
     fn        = BIOS_ROM_PATH;
 
     switch (dev->type) {
+        case ET4000_TYPE_TC6058AF: /* ISA ET4000AX (TC6058AF) */
         case ET4000_TYPE_ISA: /* ISA ET4000AX */
             dev->vram_size = device_get_config_int("memory") << 10;
             video_inform(VIDEO_FLAG_TYPE_SPECIAL, &timing_et4000_isa);
@@ -674,6 +739,8 @@ et4000_init(const device_t *info)
                       NULL, NULL);
             io_sethandler(0x03c0, 32,
                           et4000_in, NULL, NULL, et4000_out, NULL, NULL, dev);
+            if (dev->type == ET4000_TYPE_TC6058AF)
+                fn = TC6058AF_BIOS_ROM_PATH;
             break;
 
         case ET4000_TYPE_MCA: /* MCA ET4000AX */
@@ -750,7 +817,8 @@ et4000_init(const device_t *info)
             break;
     }
 
-    dev->svga.ramdac = device_add(&sc1502x_ramdac_device);
+    if (dev->type >= ET4000_TYPE_ISA)
+        dev->svga.ramdac = device_add(&sc1502x_ramdac_device);
 
     dev->vram_mask = dev->vram_size - 1;
 
@@ -790,6 +858,12 @@ et4000_force_redraw(void *priv)
     dev->svga.fullchange = changeframecount;
 }
 
+static int
+et4000_tc6058af_available(void)
+{
+    return rom_present(TC6058AF_BIOS_ROM_PATH);
+}
+
 static int
 et4000_available(void)
 {
@@ -808,6 +882,33 @@ et4000_kasan_available(void)
     return rom_present(KASAN_BIOS_ROM_PATH) && rom_present(KASAN_FONT_ROM_PATH);
 }
 
+static const device_config_t et4000_tc6058af_config[] = {
+  // clang-format off
+    {
+        .name = "memory",
+        .description = "Memory size",
+        .type = CONFIG_SELECTION,
+        .default_int = 512,
+        .selection = {
+            {
+                .description = "256 KB",
+                .value = 256
+            },
+            {
+                .description = "512 KB",
+                .value = 512
+            },
+            {
+                .description = ""
+            }
+        }
+    },
+    {
+        .type = CONFIG_END
+    }
+// clang-format on
+};
+
 static const device_config_t et4000_config[] = {
   // clang-format off
     {
@@ -839,6 +940,20 @@ static const device_config_t et4000_config[] = {
   // clang-format on
 };
 
+const device_t et4000_tc6058af_isa_device = {
+    .name          = "Tseng Labs ET4000AX (TC6058AF) (ISA)",
+    .internal_name = "et4000ax_tc6058af",
+    .flags         = DEVICE_ISA,
+    .local         = 0,
+    .init          = et4000_init,
+    .close         = et4000_close,
+    .reset         = NULL,
+    { .available = et4000_tc6058af_available },
+    .speed_changed = et4000_speed_changed,
+    .force_redraw  = et4000_force_redraw,
+    .config        = et4000_tc6058af_config
+};
+
 const device_t et4000_isa_device = {
     .name          = "Tseng Labs ET4000AX (ISA)",
     .internal_name = "et4000ax",
diff --git a/src/video/vid_et4000w32.c b/src/video/vid_et4000w32.c
index c2ce39778..bc23f224e 100644
--- a/src/video/vid_et4000w32.c
+++ b/src/video/vid_et4000w32.c
@@ -457,6 +457,7 @@ et4000w32p_recalctimings(svga_t *svga)
         }
     }
 
+#if 0
     if (svga->adv_flags & FLAG_NOSKEW) {
         /* On the Cardex ET4000/W32p-based cards, adjust text mode clocks by 1. */
         if (!(svga->gdcreg[6] & 1) && !(svga->attrregs[0x10] & 1)) { /* Text mode */
@@ -480,6 +481,7 @@ et4000w32p_recalctimings(svga_t *svga)
             }
         }
     }
+#endif
 
     if (et4000->type == ET4000W32) {
         if ((svga->gdcreg[6] & 1) || (svga->attrregs[0x10] & 1)) {
@@ -2561,6 +2563,9 @@ et4000w32p_pci_read(UNUSED(int func), int addr, void *priv)
 {
     et4000w32p_t *et4000 = (et4000w32p_t *) priv;
 
+    if (func > 0)
+        return 0xff;
+
     addr &= 0xff;
 
     switch (addr) {
@@ -2618,6 +2623,9 @@ et4000w32p_pci_write(UNUSED(int func), int addr, uint8_t val, void *priv)
     et4000w32p_t *et4000 = (et4000w32p_t *) priv;
     svga_t       *svga   = &et4000->svga;
 
+    if (func > 0)
+        return;
+
     addr &= 0xff;
 
     switch (addr) {
diff --git a/src/video/vid_s3.c b/src/video/vid_s3.c
index bcdd64d40..48740d1ce 100644
--- a/src/video/vid_s3.c
+++ b/src/video/vid_s3.c
@@ -3038,6 +3038,8 @@ s3_recalctimings(svga_t *svga)
     s3_t *s3      = (s3_t *) svga->priv;
     int   clk_sel = (svga->miscout >> 2) & 3;
 
+    svga->hdisp = svga->hdisp_old;
+
     if (!svga->scrblank && svga->attr_palette_enable) {
         if ((svga->gdcreg[6] & 1) || (svga->attrregs[0x10] & 1)) {
             if (svga->crtc[0x3a] & 0x10) { /*256+ color register*/
@@ -3047,14 +3049,13 @@ s3_recalctimings(svga_t *svga)
     }
 
     svga->ma_latch |= (s3->ma_ext << 16);
-    if (s3->chip >= S3_86C928) {
-        svga->hdisp = svga->hdisp_old;
 
+    if (s3->chip >= S3_86C928) {
         if (svga->crtc[0x5d] & 0x01)
             svga->htotal |= 0x100;
         if (svga->crtc[0x5d] & 0x02) {
             svga->hdisp_time |= 0x100;
-            svga->hdisp |= 0x100 * ((svga->seqregs[1] & 8) ? 16 : 8);
+            svga->hdisp |= 0x100 * svga->dots_per_clock;
         }
         if (svga->crtc[0x5e] & 0x01)
             svga->vtotal |= 0x400;
@@ -3072,7 +3073,8 @@ s3_recalctimings(svga_t *svga)
             svga->rowoffset |= (svga->crtc[0x51] & 0x30) << 4;
         else if (svga->crtc[0x43] & 0x04)
             svga->rowoffset |= 0x100;
-    }
+    } else if (svga->crtc[0x43] & 0x04)
+        svga->rowoffset |= 0x100;
     if (!svga->rowoffset)
         svga->rowoffset = 0x100;
 
@@ -3341,6 +3343,30 @@ s3_recalctimings(svga_t *svga)
             }
         }
     }
+
+    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 (svga->crtc[0x5d] & 0x04)
+            svga->hblankstart += 0x100;
+        if (s3->chip >= S3_VISION964) {
+            /* NOTE: The S3 Trio64V+ datasheet says this is bit 7, but then where is bit 6?
+                     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. */
+#if 0
+            pclog("svga->crtc[0x5d] = %02X\n", svga->crtc[0x5d]);
+#endif
+            if (svga->crtc[0x5d] & 0x08)
+                svga->hblank_ext = 0x40;
+            svga->hblank_end_len = 0x00000040;
+        }
+    }
+
+    svga->hblank_overscan = !(svga->crtc[0x33] & 0x20);
 }
 
 static void
diff --git a/src/video/vid_svga.c b/src/video/vid_svga.c
index 0e83c034a..3db97d3f1 100644
--- a/src/video/vid_svga.c
+++ b/src/video/vid_svga.c
@@ -202,7 +202,7 @@ svga_out(uint16_t addr, uint8_t val, void *priv)
                     break;
                 case 4:
                     svga->chain2_write = !(val & 4);
-                    svga->chain4       = val & 8;
+                    svga->chain4       = (svga->chain4 & ~8) | (val & 8);
                     svga->fast         = (svga->gdcreg[8] == 0xff && !(svga->gdcreg[3] & 0x18) && !svga->gdcreg[1]) && ((svga->chain4 && (svga->packed_chain4 || svga->force_old_addr)) || svga->fb_only) && !(svga->adv_flags & FLAG_ADDR_BY8);
                     break;
 
@@ -307,6 +307,9 @@ svga_out(uint16_t addr, uint8_t val, void *priv)
             if (((svga->gdcaddr & 15) == 5 && (val ^ o) & 0x70) || ((svga->gdcaddr & 15) == 6 && (val ^ o) & 1))
                 svga_recalctimings(svga);
             break;
+        case 0x3da:
+            svga->fcr = val;
+            break;
 
         default:
             break;
@@ -384,6 +387,9 @@ svga_in(uint16_t addr, void *priv)
             if (svga->adv_flags & FLAG_RAMDAC_SHIFT)
                 ret >>= 2;
             break;
+        case 0x3ca:
+            ret = svga->fcr;
+            break;
         case 0x3cc:
             ret = svga->miscout;
             break;
@@ -420,6 +426,8 @@ svga_in(uint16_t addr, void *priv)
 
             ret = svga->cgastat;
 
+            if ((svga->fcr & 0x08) && svga->dispon)
+                ret |= 0x08;
             break;
 
         default:
@@ -453,6 +461,14 @@ svga_recalctimings(svga_t *svga)
     double _dispontime;
     double _dispofftime;
     double disptime;
+#ifdef ENABLE_SVGA_LOG
+    int vsyncend;
+    int vblankend;
+    int hdispstart;
+    int hdispend;
+    int hsyncstart;
+    int hsyncend;
+#endif
 
     svga->vtotal      = svga->crtc[6];
     svga->dispend     = svga->crtc[0x12];
@@ -490,7 +506,7 @@ svga_recalctimings(svga_t *svga)
         svga->vblankstart |= 0x200;
     svga->vblankstart++;
 
-    svga->hdisp = svga->crtc[1] - ((svga->crtc[5] & 0x60) >> 5);
+    svga->hdisp = svga->crtc[1] - ((svga->crtc[3] & 0x60) >> 5);
     svga->hdisp++;
 
     svga->htotal = svga->crtc[0];
@@ -513,20 +529,20 @@ svga_recalctimings(svga_t *svga)
     svga->hdisp_time = svga->hdisp;
     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)) { /*Text mode*/
             if (svga->seqregs[1] & 8) {                              /*40 column*/
                 svga->render = svga_render_text_40;
-                svga->hdisp *= (svga->seqregs[1] & 1) ? 16 : 18;
-                /* Character clock is off by 1 now in 40-line modes, on all cards. */
-                svga->ma_latch--;
-                svga->hdisp += (svga->seqregs[1] & 1) ? 16 : 18;
             } else {
                 svga->render = svga_render_text_80;
-                svga->hdisp *= (svga->seqregs[1] & 1) ? 8 : 9;
             }
             svga->hdisp_old = svga->hdisp;
         } else {
-            svga->hdisp *= (svga->seqregs[1] & 8) ? 16 : 8;
             svga->hdisp_old = svga->hdisp;
 
             switch (svga->gdcreg[5] & 0x60) {
@@ -612,6 +628,26 @@ svga_recalctimings(svga_t *svga)
     } else
         svga->monitor->mon_overscan_x = 16;
 
+    svga->htotal         = svga->crtc[0];
+    svga->hblankstart    = svga->crtc[4] + 1;
+    svga->hblank_end_val = (svga->crtc[3] & 0x1f) | ((svga->crtc[5] & 0x80) ? 0x20 : 0x00);
+#if 0
+    pclog("htotal = %i, hblankstart = %i, hblank_end_val = %02X\n", svga->htotal, svga->hblankstart, svga->hblank_end_val);
+#endif
+    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);
+    } else
+        svga->dots_per_clock = 1;
+
+    /* Do svga->recalctimings_ex() here so that the above five variables can be
+       updated by said function. */
     if (vga_on) {
         if (svga->recalctimings_ex) {
             svga->recalctimings_ex(svga);
@@ -629,6 +665,20 @@ svga_recalctimings(svga_t *svga)
             xga_recalctimings(svga);
     }
 
+    svga->htotal += 6; /*+6 is required for Tyrian*/
+    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;
+
+    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);
+    }
+
     if (svga->hdisp >= 2048)
         svga->monitor->mon_overscan_x = 0;
 
@@ -640,6 +690,43 @@ svga_recalctimings(svga_t *svga)
 
     crtcconst = svga->clock * svga->char_width;
 
+#ifdef ENABLE_SVGA_LOG
+    vsyncend = (svga->vsyncstart & 0xfffffff0) | (svga->crtc[0x11] & 0x0f);
+    if (vsyncend <= svga->vsyncstart)
+        vsyncend += 0x00000010;
+    vblankend = (svga->vblankstart & 0xffffff80) | (svga->crtc[0x16] & 0x7f);
+    if (vblankend <= svga->vblankstart)
+        vblankend += 0x00000080;
+
+    hdispstart = ((svga->crtc[3] >> 5) & 3);
+    hdispend   = svga->crtc[1] + 1;
+    hsyncstart = svga->crtc[4] + ((svga->crtc[5] >> 5) & 3) + 1;
+    hsyncend   = (hsyncstart & 0xffffffe0) | (svga->crtc[5] & 0x1f);
+    if (hsyncend <= hsyncstart)
+        hsyncend += 0x00000020;
+#endif
+
+    svga_log("Last scanline in the vertical period: %i\n"
+             "First scanline after the last of active display: %i\n"
+             "First scanline with vertical retrace asserted: %i\n"
+             "First scanline after the last with vertical retrace asserted: %i\n"
+             "First scanline of blanking: %i\n"
+             "First scanline after the last of blanking: %i\n"
+             "\n"
+             "Last character in the horizontal period: %i\n"
+             "First character of active display: %i\n"
+             "First character after the last of active display: %i\n"
+             "First character with horizontal retrace asserted: %i\n"
+             "First character after the last with horizontal retrace asserted: %i\n"
+             "First character of blanking: %i\n"
+             "First character after the last of blanking: %i\n"
+             "\n"
+             "\n",
+             svga->vtotal, svga->dispend, svga->vsyncstart, vsyncend,
+             svga->vblankstart, vblankend,
+             svga->htotal, hdispstart, hdispend, hsyncstart, hsyncend,
+             svga->hblankstart, svga->hblankend);
+
     if (ibm8514_on && !svga->dev8514.local) {
         disptime    = svga->dev8514.h_total;
         _dispontime = svga->dev8514.h_disp;
@@ -878,9 +965,9 @@ svga_poll(void *priv)
 
             if (ret) {
                 if (svga->interlace && svga->oddeven)
-                    svga->ma = svga->maback = (svga->rowoffset << 1) + ((svga->crtc[5] & 0x60) >> 5);
+                    svga->ma = svga->maback = (svga->rowoffset << 1) + ((svga->crtc[3] & 0x60) >> 5) + svga->hblank_sub;
                 else
-                    svga->ma = svga->maback = ((svga->crtc[5] & 0x60) >> 5);
+                    svga->ma = svga->maback = ((svga->crtc[3] & 0x60) >> 5) + svga->hblank_sub;
                 svga->ma     = (svga->ma << 2);
                 svga->maback = (svga->maback << 2);
 
@@ -951,9 +1038,9 @@ svga_poll(void *priv)
 
             if ((dev->local && vga_on) || !dev->local) {
                 if (svga->interlace && svga->oddeven)
-                    svga->ma = svga->maback = svga->ma_latch + (svga->rowoffset << 1) + ((svga->crtc[5] & 0x60) >> 5);
+                    svga->ma = svga->maback = svga->ma_latch + (svga->rowoffset << 1) + ((svga->crtc[3] & 0x60) >> 5) + svga->hblank_sub;
                 else
-                    svga->ma = svga->maback = svga->ma_latch + ((svga->crtc[5] & 0x60) >> 5);
+                    svga->ma = svga->maback = svga->ma_latch + ((svga->crtc[3] & 0x60) >> 5) + svga->hblank_sub;
             } else if (dev->local && ibm8514_on) {
                 if (svga->interlace && svga->oddeven)
                     svga->ma = svga->maback = svga->ma_latch + (svga->rowoffset << 1);
@@ -968,6 +1055,9 @@ svga_poll(void *priv)
             if (svga->vsync_callback)
                 svga->vsync_callback(svga);
         }
+#if 0
+        if (svga->vc == lines_num) {
+#endif
         if (svga->vc == svga->vtotal) {
             svga->vc       = 0;
             svga->sc       = 0;
@@ -1090,7 +1180,8 @@ svga_init(const device_t *info, svga_t *svga, void *priv, int memsize,
 
     svga->ramdac_type = RAMDAC_6BIT;
 
-    svga->map8 = svga->pallook;
+    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_svga_render.c b/src/video/vid_svga_render.c
index c9369f09c..7ee263aa3 100644
--- a/src/video/vid_svga_render.c
+++ b/src/video/vid_svga_render.c
@@ -70,9 +70,20 @@ svga_render_blank(svga_t *svga)
             break;
     }
 
+#if 0
+    pclog("svga->displine = %i, svga->y_add = %i, svga->x_add = %i\n", svga->displine, svga->y_add, svga->x_add);
+#endif
     uint32_t *line_ptr   = &svga->monitor->target_buffer->line[svga->displine + svga->y_add][svga->x_add];
+#if 0
+    pclog("svga->hdisp = %i, svga->scrollcache = %i, char_width = %i, sizeof(uint32_t) = %i\n", svga->hdisp, svga->scrollcache, char_width, sizeof(uint32_t));
+#endif
     uint32_t  line_width = (uint32_t) (svga->hdisp + svga->scrollcache) * char_width * sizeof(uint32_t);
-    memset(line_ptr, 0, line_width);
+
+#if 0
+    pclog("line_width = %i\n", line_width);
+#endif
+    if ((svga->hdisp + svga->scrollcache) > 0)
+        memset(line_ptr, 0, line_width);
 }
 
 void
@@ -81,7 +92,7 @@ svga_render_overscan_left(svga_t *svga)
     if ((svga->displine + svga->y_add) < 0)
         return;
 
-    if (svga->scrblank || (svga->hdisp == 0))
+    if (svga->scrblank || (svga->hdisp <= 0))
         return;
 
     uint32_t *line_ptr = svga->monitor->target_buffer->line[svga->displine + svga->y_add];
@@ -97,7 +108,7 @@ svga_render_overscan_right(svga_t *svga)
     if ((svga->displine + svga->y_add) < 0)
         return;
 
-    if (svga->scrblank || (svga->hdisp == 0))
+    if (svga->scrblank || (svga->hdisp <= 0))
         return;
 
     uint32_t *line_ptr = &svga->monitor->target_buffer->line[svga->displine + svga->y_add][svga->x_add + svga->hdisp];
diff --git a/src/video/vid_table.c b/src/video/vid_table.c
index eb999eb3f..e8301e3ee 100644
--- a/src/video/vid_table.c
+++ b/src/video/vid_table.c
@@ -148,6 +148,7 @@ video_cards[] = {
     { &et4000k_isa_device                            },
     { &et2000_device                                 },
     { &et3000_isa_device                             },
+    { &et4000_tc6058af_isa_device                    },
     { &et4000_isa_device                             },
     { &et4000w32_device                              },
     { &et4000w32i_isa_device                         },