diff --git a/src/vid_et4000.c b/src/vid_et4000.c
index 25cb60d..6f2fdf2 100644
--- a/src/vid_et4000.c
+++ b/src/vid_et4000.c
@@ -71,6 +71,21 @@ void et4000_out(uint16_t addr, uint8_t val, void *p)
                 et4000->banking = val;
 //                pclog("Banking write %08X %08X %02X\n", svga->write_bank, svga->read_bank, val);
                 return;
+
+                case 0x3cf:
+                if ((svga->gdcaddr & 15) == 6)
+                {
+                        old = svga->gdcreg[6];
+                        svga_out(addr, val, svga);
+                        if ((old & 0xc) != 0 && (val & 0xc) == 0)
+                        {
+                                /*override mask - ET4000 supports linear 128k at A0000*/
+                                svga->banked_mask = 0x1ffff;
+                        }
+                        return;
+                }
+                break;
+
                 case 0x3D4:
                 svga->crtcreg = val & 0x3f;
                 return;
diff --git a/src/vid_et4000w32.c b/src/vid_et4000w32.c
index e8a8e8f..ae748ef 100644
--- a/src/vid_et4000w32.c
+++ b/src/vid_et4000w32.c
@@ -337,7 +337,7 @@ void et4000w32p_recalcmapping(et4000w32p_t *et4000)
                         case 0x0: case 0x4: case 0x8: case 0xC: /*128k at A0000*/
                         mem_mapping_set_addr(&svga->mapping, 0xa0000, 0x20000);
                         mem_mapping_disable(&et4000->mmu_mapping);
-                        svga->banked_mask = 0xffff;
+                        svga->banked_mask = 0x1ffff;
                         break;
                         case 0x1: /*64k at A0000*/
                         mem_mapping_set_addr(&svga->mapping, 0xa0000, 0x10000);
diff --git a/src/vid_tvga.c b/src/vid_tvga.c
index 59e11e3..6a42ac4 100644
--- a/src/vid_tvga.c
+++ b/src/vid_tvga.c
@@ -109,6 +109,15 @@ void tvga_out(uint16_t addr, uint8_t val, void *p)
                 case 0x3CF:
                 switch (svga->gdcaddr & 15)
                 {
+                        case 0x6:
+                        old = svga->gdcreg[6];
+                        svga_out(addr, val, svga);
+                        if ((old & 0xc) != 0 && (val & 0xc) == 0)
+                        {
+                                /*override mask - TVGA supports linear 128k at A0000*/
+                                svga->banked_mask = 0x1ffff;
+                        }
+                        return;
                         case 0xE:
                         svga->gdcreg[0xe] = val ^ 2;
                         tvga->tvga_3d9 = svga->gdcreg[0xe] & 0xf;