Ported the 128K mapping fixes to 86Box.

src/video/vid_et4000.c

@@ -245,6 +245,15 @@ et4000_out(uint16_t addr, uint8_t val, void *priv)
 				svga->read_bank = ((dev->banking >> 4) & 0x0f) * 0x10000;
 			} else
 				svga->write_bank = svga->read_bank = 0;
+			
+                        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;
 

src/video/vid_et4000w32.c

@@ -454,7 +454,7 @@ 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);

src/video/vid_tvga.c

@@ -127,6 +127,15 @@ 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;