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Diffstat (limited to 'src/devices/bus/odyssey2/ktaa.cpp')
-rw-r--r--src/devices/bus/odyssey2/ktaa.cpp59
1 files changed, 47 insertions, 12 deletions
diff --git a/src/devices/bus/odyssey2/ktaa.cpp b/src/devices/bus/odyssey2/ktaa.cpp
index 4f1fba25153..f14fdf7c113 100644
--- a/src/devices/bus/odyssey2/ktaa.cpp
+++ b/src/devices/bus/odyssey2/ktaa.cpp
@@ -11,13 +11,33 @@ Bankswitched ROM with page size of 3KB.
#include "emu.h"
#include "ktaa.h"
-DEFINE_DEVICE_TYPE(O2_ROM_KTAA, o2_ktaa_device, "o2_ktaa", "Odyssey 2 Homebrew KTAA")
-
+namespace {
//-------------------------------------------------
-// o2_ktaa_device - constructor
+// initialization
//-------------------------------------------------
+class o2_ktaa_device : public device_t, public device_o2_cart_interface
+{
+public:
+ o2_ktaa_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock);
+
+protected:
+ virtual void device_start() override;
+
+ virtual void cart_init() override;
+
+ virtual u8 read_rom04(offs_t offset) override;
+ virtual u8 read_rom0c(offs_t offset) override { return read_rom04(offset + 0x800); }
+
+ virtual void write_p1(u8 data) override { m_bank = data & m_bank_mask; }
+
+private:
+ u32 m_page_size = 0;
+ u8 m_bank_mask = 0;
+ u8 m_bank = 0;
+};
+
o2_ktaa_device::o2_ktaa_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock) :
device_t(mconfig, O2_ROM_KTAA, tag, owner, clock),
device_o2_cart_interface(mconfig, *this)
@@ -30,11 +50,25 @@ void o2_ktaa_device::device_start()
void o2_ktaa_device::cart_init()
{
- u32 size = m_rom.bytes();
- if (size != 0xc00 && size != 0xc00*2 && size != 0xc00*4)
- fatalerror("o2_ktaa_device: ROM size must be multiple of 3KB\n");
+ 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;
+ }
- m_bank_mask = (size / 0xc00) - 1;
+ 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 +78,11 @@ void o2_ktaa_device::cart_init()
u8 o2_ktaa_device::read_rom04(offs_t offset)
{
- return m_rom[offset + m_bank * 0xc00];
+ offset += m_page_size - 0xc00;
+ return m_rom[offset + m_bank * m_page_size];
}
-u8 o2_ktaa_device::read_rom0c(offs_t offset)
-{
- return m_rom[offset + 0x800 + m_bank * 0xc00];
-}
+} // anonymous namespace
+
+
+DEFINE_DEVICE_TYPE_PRIVATE(O2_ROM_KTAA, device_o2_cart_interface, o2_ktaa_device, "o2_ktaa", "Videopac+ KTAA Cartridge")