diff --git a/src/mess/drivers/msx.c b/src/mess/drivers/msx.c
index 2389586dadd..9ebceac73f2 100644
--- a/src/mess/drivers/msx.c
+++ b/src/mess/drivers/msx.c
@@ -1801,7 +1801,7 @@ MSX_LAYOUT_INIT (phc28s)
 	MSX_LAYOUT_SLOT (0, 0, 0, 2, ROM, 0x8000, 0x0000)
 	MSX_LAYOUT_SLOT (1, 0, 0, 4, CARTRIDGE1, 0x0000, 0x0000)
 	MSX_LAYOUT_SLOT (2, 0, 0, 4, CARTRIDGE2, 0x0000, 0x0000)
-	MSX_LAYOUT_SLOT (3, 0, 2, 4, RAM, 0x8000, 0x0000)   /* 32KB RAM */
+	MSX_LAYOUT_SLOT (3, 0, 2, 2, RAM, 0x8000, 0x0000)   /* 32KB RAM */
 MSX_LAYOUT_END
 
 /* MSX - Sanyo Wavy MPC-10 */
@@ -2245,7 +2245,7 @@ MSX_LAYOUT_INIT (yis503)
 	MSX_LAYOUT_SLOT (0, 0, 0, 2, ROM, 0x8000, 0x0000)
 	MSX_LAYOUT_SLOT (1, 0, 0, 4, CARTRIDGE1, 0x0000, 0x0000)
 	MSX_LAYOUT_SLOT (2, 0, 0, 4, CARTRIDGE2, 0x0000, 0x0000)
-	MSX_LAYOUT_SLOT (3, 0, 0, 2, ROM, 0xC000, 0x0000)   /* Fill FF */
+	MSX_LAYOUT_SLOT (3, 0, 0, 3, ROM, 0xC000, 0x0000)   /* Fill FF */
 	MSX_LAYOUT_SLOT (3, 0, 2, 2, RAM, 0x8000, 0x0000)   /* 32KB RAM */
 MSX_LAYOUT_END
 
@@ -2710,7 +2710,7 @@ MSX_LAYOUT_INIT (fs5000)
 	MSX_LAYOUT_SLOT (2, 0, 0, 4, CARTRIDGE2, 0x0000, 0x0000)
 	MSX_LAYOUT_SLOT (3, 0, 0, 1, ROM, 0x4000, 0x8000)
 	MSX_LAYOUT_SLOT (3, 0, 1, 2, ROM, 0x8000, 0x28000)
-	MSX_LAYOUT_SLOT (3, 1, 1, 1, ROM, 0x8000, 0x20000)
+	MSX_LAYOUT_SLOT (3, 1, 1, 2, ROM, 0x8000, 0x20000)
 	MSX_LAYOUT_SLOT (3, 2, 0, 4, RAM_MM, 0x20000, 0x0000)   /* 128KB Mapper RAM */
 	MSX_LAYOUT_SLOT (3, 3, 1, 1, DISK_ROM2, 0x4000, 0xc000)
 	MSX_LAYOUT_KANJI (0x30000)
@@ -3083,6 +3083,8 @@ ROM_START (vg8230j)
 	ROM_LOAD ("8230jbios.rom", 0x0000, 0x8000, CRC(9b3e7b97) SHA1(0081ea0d25bc5cd8d70b60ad8cfdc7307812c0fd))
 	ROM_LOAD ("8230jext.rom", 0x8000, 0x4000, CRC(4a48779c) SHA1(b8e30d604d319d511cbfbc61e5d8c38fbb9c5a33))
 	ROM_LOAD ("8230jdisk.rom", 0xc000, 0x4000, CRC(7639758a) SHA1(0f5798850d11b316a4254b222ca08cc4ad6d4da2))
+	/* 0x10000 - 0x1ffff reserved for optional fmpac roms from msx2 parent set */
+	ROM_FILL (0x10000, 0x10000, 0)
 	ROM_LOAD ("8230jkfn.rom", 0x20000, 0x20000, CRC(5a59926e) SHA1(6acaf2eeb57f65f7408235d5e07b7563229de799))
 ROM_END
 
@@ -3191,7 +3193,7 @@ MSX_LAYOUT_INIT (mpc25fd)
 	MSX_LAYOUT_SLOT (2, 0, 0, 4, CARTRIDGE2, 0x0000, 0x0000)
 	MSX_LAYOUT_SLOT (2, 3, 0, 1, ROM, 0x4000, 0x8000)
 	MSX_LAYOUT_SLOT (3, 1, 1, 1, DISK_ROM, 0x4000, 0xc000)
-	MSX_LAYOUT_SLOT (3, 2, 0, 0, RAM_MM, 0x10000, 0x0000)   /* 128KB?? RAM */
+	MSX_LAYOUT_SLOT (3, 2, 0, 4, RAM_MM, 0x10000, 0x0000)   /* 128KB?? RAM */
 MSX_LAYOUT_END
 
 /* MSX2 - Sanyo Wavy PHC-23 */
@@ -4169,7 +4171,7 @@ MSX_LAYOUT_INIT (hbf9sp)
 	MSX_LAYOUT_SLOT (2, 0, 0, 4, CARTRIDGE2, 0x0000, 0x0000)
 	MSX_LAYOUT_SLOT (3, 0, 0, 1, ROM, 0x4000, 0x8000)
 	MSX_LAYOUT_SLOT (3, 0, 2, 1, ROM, 0x4000, 0x20000)
-	MSX_LAYOUT_SLOT (3, 1, 2, 4, ROM, 0x8000, 0x24000)
+	MSX_LAYOUT_SLOT (3, 1, 2, 2, ROM, 0x8000, 0x24000)
 	MSX_LAYOUT_SLOT (3, 2, 0, 4, RAM_MM, 0x10000, 0x0000)   /* 64KB?? Mapper RAM */
 MSX_LAYOUT_END
 
@@ -4196,7 +4198,7 @@ MSX_LAYOUT_INIT (fsa1gt)
 	MSX_LAYOUT_SLOT (3, 0, 0, 4, RAM_MM, 0x20000, 0x0000)   /* 128KB?? Mapper RAM */
 	MSX_LAYOUT_SLOT (3, 1, 0, 1, ROM, 0x4000, 0x8000)
 	MSX_LAYOUT_SLOT (3, 1, 1, 2, ROM, 0x8000, 0x30000)
-	MSX_LAYOUT_SLOT (3, 2, 1, 4, ROM, 0xc000, 0x20000)
+	MSX_LAYOUT_SLOT (3, 2, 1, 3, ROM, 0xc000, 0x20000)
 	MSX_LAYOUT_SLOT (3, 3, 0, 4, ROM, 0x10000, 0x80000)
 MSX_LAYOUT_END
 
@@ -4223,7 +4225,7 @@ MSX_LAYOUT_INIT (fsa1st)
 	MSX_LAYOUT_SLOT (3, 0, 0, 4, RAM_MM, 0x20000, 0x0000)   /* 128KB?? Mapper RAM */
 	MSX_LAYOUT_SLOT (3, 1, 0, 1, ROM, 0x4000, 0x8000)
 	MSX_LAYOUT_SLOT (3, 1, 1, 2, ROM, 0x8000, 0x30000)
-	MSX_LAYOUT_SLOT (3, 2, 1, 4, ROM, 0xc000, 0x20000)
+	MSX_LAYOUT_SLOT (3, 2, 1, 3, ROM, 0xc000, 0x20000)
 	MSX_LAYOUT_SLOT (3, 3, 0, 4, ROM, 0x10000, 0x80000)
 MSX_LAYOUT_END