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-rw-r--r--src/devices/bus/bbc/internal/we32kram.cpp142
1 files changed, 142 insertions, 0 deletions
diff --git a/src/devices/bus/bbc/internal/we32kram.cpp b/src/devices/bus/bbc/internal/we32kram.cpp
new file mode 100644
index 00000000000..ec21a7efb9d
--- /dev/null
+++ b/src/devices/bus/bbc/internal/we32kram.cpp
@@ -0,0 +1,142 @@
+// license:BSD-3-Clause
+// copyright-holders:Nigel Barnes
+/**********************************************************************
+
+ Watford Electronics 32K RAM card
+
+ http://chrisacorns.computinghistory.org.uk/8bit_Upgrades/WE_32KRAMcard.html
+
+**********************************************************************/
+
+
+#include "emu.h"
+#include "we32kram.h"
+
+
+//**************************************************************************
+// DEVICE DEFINITIONS
+//**************************************************************************
+
+DEFINE_DEVICE_TYPE(BBC_WE32KRAM, bbc_we32kram_device, "bbc_we32kram", "Watford Electronics 32K Shadow RAM");
+
+
+//-------------------------------------------------
+// ROM( we32kram )
+//-------------------------------------------------
+
+ROM_START(we32kram)
+ ROM_REGION(0x4000, "exp_rom", 0)
+ ROM_SYSTEM_BIOS(0, "240", "v2.40")
+ ROMX_LOAD("we32kram_v2.40.rom", 0x0000, 0x2000, CRC(db9c3a1a) SHA1(0a5efb084eb1ae353b9c79c026e9e26cd7695293), ROM_BIOS(0))
+ ROM_SYSTEM_BIOS(1, "200", "v2.00")
+ ROMX_LOAD("we32kram_v2.00.rom", 0x0000, 0x2000, CRC(1eff9b23) SHA1(98a3084b20c92427c2e9def58ade96f42659e20a), ROM_BIOS(1))
+ ROM_SYSTEM_BIOS(2, "100", "v1.00")
+ ROMX_LOAD("we32kram_v1.00.rom", 0x0000, 0x2000, CRC(7962b5db) SHA1(1b59a3354cfc704ad8aa60b0ed16e4cd2d815031), ROM_BIOS(2))
+ROM_END
+
+//-------------------------------------------------
+// rom_region - device-specific ROM region
+//-------------------------------------------------
+
+const tiny_rom_entry *bbc_we32kram_device::device_rom_region() const
+{
+ return ROM_NAME(we32kram);
+}
+
+
+//**************************************************************************
+// LIVE DEVICE
+//**************************************************************************
+
+//-------------------------------------------------
+// bbc_we32kram_device - constructor
+//-------------------------------------------------
+
+bbc_we32kram_device::bbc_we32kram_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
+ : device_t(mconfig, BBC_WE32KRAM, tag, owner, clock)
+ , device_bbc_internal_interface(mconfig, *this)
+{
+}
+
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void bbc_we32kram_device::device_start()
+{
+ m_shadow = 2;
+ m_ram = std::make_unique<uint8_t[]>(0x8000);
+
+ /* register for save states */
+ save_item(NAME(m_shadow));
+ save_pointer(NAME(m_ram), 0x8000);
+}
+
+//-------------------------------------------------
+// device_reset - device-specific reset
+//-------------------------------------------------
+
+void bbc_we32kram_device::device_reset()
+{
+ address_space &program = m_maincpu->space(AS_PROGRAM);
+
+ program.install_write_handler(0xfffc, 0xffff, write8sm_delegate(*this, FUNC(bbc_we32kram_device::control_w)));
+}
+
+//**************************************************************************
+// IMPLEMENTATION
+//**************************************************************************
+
+void bbc_we32kram_device::control_w(offs_t offset, uint8_t data)
+{
+ m_shadow = offset;
+}
+
+uint8_t bbc_we32kram_device::ram_r(offs_t offset)
+{
+ uint8_t data = 0xff;
+
+ switch (m_shadow)
+ {
+ case 0:
+ /* &fffc - swap whole memory */
+ data = m_ram[offset];
+ break;
+ case 2:
+ /* &fffe - select BBC ram */
+ data = m_mb_ram->pointer()[offset];
+ break;
+ case 3:
+ /* &ffff - select Watford ram */
+ if (offset >= 0x3000)
+ data = m_ram[offset];
+ else
+ data = m_mb_ram->pointer()[offset];
+ break;
+ }
+
+ return data;
+}
+
+void bbc_we32kram_device::ram_w(offs_t offset, uint8_t data)
+{
+ switch (m_shadow)
+ {
+ case 0:
+ /* &fffc - swap whole memory */
+ m_ram[offset] = data;
+ break;
+ case 2:
+ /* &fffe - select BBC ram */
+ m_mb_ram->pointer()[offset] = data;
+ break;
+ case 3:
+ /* &ffff - select Watford ram */
+ if (offset >= 0x3000)
+ m_ram[offset] = data;
+ else
+ m_mb_ram->pointer()[offset] = data;
+ break;
+ }
+}