summaryrefslogtreecommitdiffstatshomepage
path: root/src/devices/bus/bbc/cart/mega256.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'src/devices/bus/bbc/cart/mega256.cpp')
-rw-r--r--src/devices/bus/bbc/cart/mega256.cpp97
1 files changed, 97 insertions, 0 deletions
diff --git a/src/devices/bus/bbc/cart/mega256.cpp b/src/devices/bus/bbc/cart/mega256.cpp
new file mode 100644
index 00000000000..f0348df2e74
--- /dev/null
+++ b/src/devices/bus/bbc/cart/mega256.cpp
@@ -0,0 +1,97 @@
+// license:BSD-3-Clause
+// copyright-holders:Nigel Barnes
+/***************************************************************************
+
+ Solidisk Mega 256 cartridge emulation
+
+ http://chrisacorns.computinghistory.org.uk/8bit_Upgrades/Solidisk_Mega256.html
+
+***************************************************************************/
+
+#include "emu.h"
+#include "mega256.h"
+
+
+//**************************************************************************
+// DEVICE DEFINITIONS
+//**************************************************************************
+
+DEFINE_DEVICE_TYPE(BBC_MEGA256, bbc_mega256_device, "bbc_mega256", "Solidisk Mega 256 cartridge")
+
+
+//**************************************************************************
+// LIVE DEVICE
+//**************************************************************************
+
+//-------------------------------------------------
+// bbc_mega256_device - constructor
+//-------------------------------------------------
+
+bbc_mega256_device::bbc_mega256_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
+ : device_t(mconfig, BBC_MEGA256, tag, owner, clock)
+ , device_bbc_cart_interface(mconfig, *this)
+ , m_page(0)
+{
+}
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void bbc_mega256_device::device_start()
+{
+ // register for save states
+ save_item(NAME(m_page));
+}
+
+//-------------------------------------------------
+// device_reset - device-specific reset
+//-------------------------------------------------
+
+void bbc_mega256_device::device_reset()
+{
+ m_page = 0x00;
+}
+
+//-------------------------------------------------
+// read - cartridge data read
+//-------------------------------------------------
+
+uint8_t bbc_mega256_device::read(offs_t offset, int infc, int infd, int romqa, int oe, int oe2)
+{
+ uint8_t data = 0xff;
+
+ if (oe)
+ {
+ if (romqa)
+ {
+ data = m_rom[offset & 0x1fff];
+ }
+ else
+ {
+ data = m_ram[(offset & 0x3fff) | (m_page << 14)];
+ }
+ }
+
+ return data;
+}
+
+//-------------------------------------------------
+// write - cartridge data write
+//-------------------------------------------------
+
+void bbc_mega256_device::write(offs_t offset, uint8_t data, int infc, int infd, int romqa, int oe, int oe2)
+{
+ if (oe)
+ {
+ if (romqa)
+ {
+ // Not known whether this latch is fully decoded.
+ if (offset == 0x3fff) m_page = data & 0x0f;
+ }
+ else
+ {
+ m_ram[(offset & 0x3fff) | (m_page << 14)] = data;
+ }
+ }
+}