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-rw-r--r--src/devices/bus/c64/dqbb.cpp121
1 files changed, 121 insertions, 0 deletions
diff --git a/src/devices/bus/c64/dqbb.cpp b/src/devices/bus/c64/dqbb.cpp
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+++ b/src/devices/bus/c64/dqbb.cpp
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+// license:BSD-3-Clause
+// copyright-holders:Curt Coder
+/**********************************************************************
+
+ Brown Boxes Double Quick Brown Box emulation
+
+**********************************************************************/
+
+/*
+
+ TODO:
+
+ - 64/128 mode switch
+ - dump of the initial NVRAM contents
+
+*/
+
+#include "dqbb.h"
+
+
+
+//**************************************************************************
+// DEVICE DEFINITIONS
+//**************************************************************************
+
+const device_type C64_DQBB = &device_creator<c64_dqbb_cartridge_device>;
+
+
+
+//**************************************************************************
+// LIVE DEVICE
+//**************************************************************************
+
+//-------------------------------------------------
+// c64_dqbb_cartridge_device - constructor
+//-------------------------------------------------
+
+c64_dqbb_cartridge_device::c64_dqbb_cartridge_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) :
+ device_t(mconfig, C64_DQBB, "C64 Double Quick Brown Box cartridge", tag, owner, clock, "c64_dqbb", __FILE__),
+ device_c64_expansion_card_interface(mconfig, *this),
+ device_nvram_interface(mconfig, *this)
+{
+}
+
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void c64_dqbb_cartridge_device::device_start()
+{
+ // allocate memory
+ m_nvram.allocate(0x4000);
+
+ // state saving
+ save_item(NAME(m_cs));
+ save_item(NAME(m_we));
+}
+
+
+//-------------------------------------------------
+// device_reset - device-specific reset
+//-------------------------------------------------
+
+void c64_dqbb_cartridge_device::device_reset()
+{
+ m_exrom = 0; // TODO 1 in 128 mode
+ m_game = 1;
+ m_cs = 0;
+ m_we = 0;
+}
+
+
+//-------------------------------------------------
+// c64_cd_r - cartridge data read
+//-------------------------------------------------
+
+UINT8 c64_dqbb_cartridge_device::c64_cd_r(address_space &space, offs_t offset, UINT8 data, int sphi2, int ba, int roml, int romh, int io1, int io2)
+{
+ if (!m_cs && (!roml || !romh))
+ {
+ data = m_nvram[offset & 0x3fff];
+ }
+
+ return data;
+}
+
+
+//-------------------------------------------------
+// c64_cd_w - cartridge data write
+//-------------------------------------------------
+
+void c64_dqbb_cartridge_device::c64_cd_w(address_space &space, offs_t offset, UINT8 data, int sphi2, int ba, int roml, int romh, int io1, int io2)
+{
+ if (!m_cs && m_we && (offset >= 0x8000 && offset < 0xc000))
+ {
+ m_nvram[offset & 0x3fff] = data;
+ }
+ else if (!io1)
+ {
+ /*
+
+ bit description
+
+ 0
+ 1
+ 2 GAME
+ 3
+ 4 WE
+ 5
+ 6 EXROM
+ 7 _CS
+
+ */
+
+ m_exrom = !BIT(data, 6);
+ m_game = !BIT(data, 2);
+ m_we = BIT(data, 4);
+ m_cs = BIT(data, 7);
+ }
+}