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Diffstat (limited to 'src/devices/bus/odyssey2/ktaa.cpp')
-rw-r--r--src/devices/bus/odyssey2/ktaa.cpp32
1 files changed, 21 insertions, 11 deletions
diff --git a/src/devices/bus/odyssey2/ktaa.cpp b/src/devices/bus/odyssey2/ktaa.cpp
index d968a35ed24..b9cf38bbf95 100644
--- a/src/devices/bus/odyssey2/ktaa.cpp
+++ b/src/devices/bus/odyssey2/ktaa.cpp
@@ -30,11 +30,25 @@ void o2_ktaa_device::device_start()
void o2_ktaa_device::cart_init()
{
- u32 size = m_rom_size;
- if (size != 0xc00 && size != 0xc00*2 && size != 0xc00*4)
- fatalerror("o2_ktaa_device: ROM size must be multiple of 3KB\n");
-
- m_bank_mask = (size / 0xc00) - 1;
+ bool err = false;
+
+ if (m_rom_size & (m_rom_size - 1))
+ {
+ // freely released binary file is 12KB
+ err = m_rom_size != 0xc00 && m_rom_size != 0xc00*2 && m_rom_size != 0xc00*4;
+ m_page_size = 0xc00;
+ }
+ else
+ {
+ // actual ROM is 16KB(27C128), first 1KB of each 4KB block is empty
+ err = m_rom_size < 0x1000;
+ m_page_size = 0x1000;
+ }
+
+ if (err)
+ fatalerror("o2_ktaa_device: ROM size must be multiple of 3KB or 4KB\n");
+
+ m_bank_mask = (m_rom_size / m_page_size) - 1;
}
@@ -44,10 +58,6 @@ void o2_ktaa_device::cart_init()
u8 o2_ktaa_device::read_rom04(offs_t offset)
{
- return m_rom[offset + m_bank * 0xc00];
-}
-
-u8 o2_ktaa_device::read_rom0c(offs_t offset)
-{
- return m_rom[offset + 0x800 + m_bank * 0xc00];
+ offset += m_page_size - 0xc00;
+ return m_rom[offset + m_bank * m_page_size];
}