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-rw-r--r--src/mame/machine/amstrad.cpp11
1 files changed, 9 insertions, 2 deletions
diff --git a/src/mame/machine/amstrad.cpp b/src/mame/machine/amstrad.cpp
index d12e4d597a3..0725ab3142e 100644
--- a/src/mame/machine/amstrad.cpp
+++ b/src/mame/machine/amstrad.cpp
@@ -2936,7 +2936,14 @@ void amstrad_state::enumerate_roms()
if (m_system_type == SYSTEM_PLUS || m_system_type == SYSTEM_GX4000)
{
uint8_t *crt = m_region_cart->base();
- int bank_num = (m_cart->get_rom_size() / 0x4000);
+ int bank_mask = 0x7ffff;
+
+ if (m_cart->get_rom_size() <= 0x20000)
+ bank_mask = 0x1ffff;
+ else if (m_cart->get_rom_size() <= 0x40000)
+ bank_mask = 0x3ffff;
+ else if (m_cart->get_rom_size() <= 0x80000)
+ bank_mask = 0x7ffff;
/* ROMs are stored on the inserted cartridge in the Plus/GX4000 */
for (int i = 0; i < 128; i++) // fill ROM table
@@ -2946,7 +2953,7 @@ void amstrad_state::enumerate_roms()
for(int i = 128; i < 160; i++)
{
- m_Amstrad_ROM_Table[i] = &crt[((i - 128) % bank_num) * 0x4000];
+ m_Amstrad_ROM_Table[i] = &crt[((i - 128) & bank_mask) * 0x4000];
}
m_Amstrad_ROM_Table[7] = &crt[0xc000];
slot7 = true;