diff --git a/src/devices/machine/gt64xxx.cpp b/src/devices/machine/gt64xxx.cpp
index edf4f0b1d3f..22c1bb3f70b 100644
--- a/src/devices/machine/gt64xxx.cpp
+++ b/src/devices/machine/gt64xxx.cpp
@@ -208,6 +208,10 @@ void gt64xxx_device::map_cpu_space()
 	{
 		winStart = (m_reg[GREG_RAS_1_0_LO + 0x10 / 4 * (ramIndex/2)] << 21) | (m_reg[GREG_RAS0_LO + 0x8 / 4 * ramIndex] << 20);
 		winEnd = (m_reg[GREG_RAS_1_0_LO + 0x10 / 4 * (ramIndex / 2)] << 21) | (m_reg[GREG_RAS0_HI + 0x8 / 4 * ramIndex] << 20) | 0xfffff;
+		// Cap window end at physical memory bounds
+		uint32_t winSize = winEnd - winStart + 1;
+		if (winSize > m_ram[ramIndex].size() * 4)
+			winEnd = winStart + m_ram[ramIndex].size() * 4 - 1;
 		//m_ram[ramIndex].resize((winEnd + 1 - winStart) / 4);
 		if (m_ram[ramIndex].size()>0)
 			m_cpu_space->install_ram(winStart, winEnd, m_ram[ramIndex].data());
diff --git a/src/mame/drivers/seattle.cpp b/src/mame/drivers/seattle.cpp
index b331c8f0742..030bf9108f6 100644
--- a/src/mame/drivers/seattle.cpp
+++ b/src/mame/drivers/seattle.cpp
@@ -1751,7 +1751,7 @@ static MACHINE_CONFIG_START( seattle_common, seattle_state )
 	MCFG_GT64XXX_SET_CS(1, seattle_cs1_map)
 	MCFG_GT64XXX_SET_CS(2, seattle_cs2_map)
 	MCFG_GT64XXX_SET_CS(3, seattle_cs3_map)
-	MCFG_GT64XX_SET_SIMM0(0x00c00000)
+	MCFG_GT64XX_SET_SIMM0(0x00800000)
 
 	MCFG_IDE_PCI_ADD(PCI_ID_IDE, 0x100b0002, 0x01, 0x0)
 	MCFG_IDE_PCI_IRQ_ADD(":maincpu", IDE_IRQ_NUM)