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Diffstat (limited to 'src/devices/bus/bbc/rom/nvram.cpp')
-rw-r--r--src/devices/bus/bbc/rom/nvram.cpp58
1 files changed, 58 insertions, 0 deletions
diff --git a/src/devices/bus/bbc/rom/nvram.cpp b/src/devices/bus/bbc/rom/nvram.cpp
new file mode 100644
index 00000000000..0d24f30c8bd
--- /dev/null
+++ b/src/devices/bus/bbc/rom/nvram.cpp
@@ -0,0 +1,58 @@
+// license:BSD-3-Clause
+// copyright-holders:Nigel Barnes
+/***************************************************************************
+
+ BBC Micro Sideways RAM (Battery Backup) emulation
+
+***************************************************************************/
+
+#include "emu.h"
+#include "nvram.h"
+
+
+//**************************************************************************
+// DEVICE DEFINITIONS
+//**************************************************************************
+
+DEFINE_DEVICE_TYPE(BBC_NVRAM, bbc_nvram_device, "bbc_nvram", "BBC Micro Sideways RAM (Battery Backup)")
+
+//**************************************************************************
+// LIVE DEVICE
+//**************************************************************************
+
+//-------------------------------------------------
+// bbc_nvram_device - constructor
+//-------------------------------------------------
+
+bbc_nvram_device::bbc_nvram_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
+ : device_t(mconfig, BBC_NVRAM, tag, owner, clock)
+ , device_bbc_rom_interface(mconfig, *this)
+{
+}
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void bbc_nvram_device::device_start()
+{
+ nvram_alloc(0x4000);
+}
+
+//-------------------------------------------------
+// read
+//-------------------------------------------------
+
+uint8_t bbc_nvram_device::read(offs_t offset)
+{
+ return get_nvram_base()[offset & (get_nvram_size() - 1)];
+}
+
+//-------------------------------------------------
+// write
+//-------------------------------------------------
+
+void bbc_nvram_device::write(offs_t offset, uint8_t data)
+{
+ get_nvram_base()[offset & (get_nvram_size() - 1)] = data;
+}