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-rw-r--r--src/devices/bus/bbc/1mhzbus/ramdisc.cpp203
1 files changed, 203 insertions, 0 deletions
diff --git a/src/devices/bus/bbc/1mhzbus/ramdisc.cpp b/src/devices/bus/bbc/1mhzbus/ramdisc.cpp
new file mode 100644
index 00000000000..ef3c3265dbe
--- /dev/null
+++ b/src/devices/bus/bbc/1mhzbus/ramdisc.cpp
@@ -0,0 +1,203 @@
+// license:BSD-3-Clause
+// copyright-holders:Nigel Barnes
+/**********************************************************************
+
+ Morley Electronics RAM Disc
+
+ Notes:
+ - 1MB model has 4096 sectors &0000 to &0fff
+ - 2MB model has 8192 sectors &0000 to &1fff
+
+**********************************************************************/
+
+
+#include "emu.h"
+#include "ramdisc.h"
+
+
+//**************************************************************************
+// DEVICE DEFINITIONS
+//**************************************************************************
+
+DEFINE_DEVICE_TYPE(BBC_RAMDISC, bbc_ramdisc_device, "bbc_ramdisc", "Morley Electronics RAM Disc");
+
+
+//-------------------------------------------------
+// INPUT_PORTS( ramdisc )
+//-------------------------------------------------
+
+static INPUT_PORTS_START(ramdisc)
+ PORT_START("POWER")
+ PORT_CONFNAME(0x01, 0x01, "Power") PORT_CHANGED_MEMBER(DEVICE_SELF, bbc_ramdisc_device, power_changed, 0)
+ PORT_CONFSETTING(0x00, DEF_STR(Off))
+ PORT_CONFSETTING(0x01, DEF_STR(On))
+INPUT_PORTS_END
+
+//-------------------------------------------------
+// input_ports - device-specific input ports
+//-------------------------------------------------
+
+ioport_constructor bbc_ramdisc_device::device_input_ports() const
+{
+ return INPUT_PORTS_NAME(ramdisc);
+}
+
+//-------------------------------------------------
+// ROM( ramdisc )
+//-------------------------------------------------
+
+ROM_START(ramdisc)
+ ROM_REGION(0x4000, "exp_rom", 0)
+ ROM_LOAD("ramdisc101.rom", 0x0000, 0x4000, CRC(627568c2) SHA1(17e727998756fe35ff451fd2ce1d4b5977be24fc))
+ROM_END
+
+//-------------------------------------------------
+// device_add_mconfig - add device configuration
+//-------------------------------------------------
+
+void bbc_ramdisc_device::device_add_mconfig(machine_config &config)
+{
+ /* ram disk */
+ NVRAM(config, "nvram", nvram_device::DEFAULT_NONE);
+
+ BBC_1MHZBUS_SLOT(config, m_1mhzbus, DERIVED_CLOCK(1, 1), bbc_1mhzbus_devices, nullptr);
+ m_1mhzbus->irq_handler().set(m_1mhzbus, FUNC(bbc_1mhzbus_slot_device::irq_w));
+ m_1mhzbus->nmi_handler().set(m_1mhzbus, FUNC(bbc_1mhzbus_slot_device::nmi_w));
+}
+
+//-------------------------------------------------
+// rom_region - device-specific ROM region
+//-------------------------------------------------
+
+const tiny_rom_entry *bbc_ramdisc_device::device_rom_region() const
+{
+ return ROM_NAME(ramdisc);
+}
+
+//**************************************************************************
+// LIVE DEVICE
+//**************************************************************************
+
+//-------------------------------------------------
+// bbc_ramdisc_device - constructor
+//-------------------------------------------------
+
+bbc_ramdisc_device::bbc_ramdisc_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
+ : device_t(mconfig, BBC_RAMDISC, tag, owner, clock)
+ , device_bbc_1mhzbus_interface(mconfig, *this)
+ , m_1mhzbus(*this, "1mhzbus")
+ , m_nvram(*this, "nvram")
+ , m_power(*this, "POWER")
+ , m_sector(0)
+{
+}
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void bbc_ramdisc_device::device_start()
+{
+ /* define 2mb ram */
+ m_ram = std::make_unique<uint8_t[]>(RAM_SIZE);
+ m_nvram->set_base(m_ram.get(), RAM_SIZE);
+
+ /* register for save states */
+ save_pointer(NAME(m_ram), RAM_SIZE);
+ save_item(NAME(m_sector));
+}
+
+
+//**************************************************************************
+// IMPLEMENTATION
+//**************************************************************************
+
+INPUT_CHANGED_MEMBER(bbc_ramdisc_device::power_changed)
+{
+ /* clear RAM on power off */
+ if (!newval)
+ {
+ memset(m_ram.get(), 0xff, RAM_SIZE);
+ }
+}
+
+uint8_t bbc_ramdisc_device::fred_r(offs_t offset)
+{
+ uint8_t data = 0xff;
+
+ if (m_power->read())
+ {
+ switch (offset)
+ {
+ case 0xc0:
+ /* sector LSB */
+ data = m_sector & 0x00ff;
+ break;
+ case 0xc2:
+ /* sector MSB */
+ data = (m_sector & 0xff00) >> 8;
+ break;
+ case 0xc1:
+ case 0xc3:
+ /* TODO: unknown purpose, must return 0x3f or 0x5f */
+ data = 0x3f;
+ logerror("Read %04x -> %02x\n", offset | 0xfcc0, data);
+ break;
+ }
+ }
+
+ data &= m_1mhzbus->fred_r(offset);
+
+ return data;
+}
+
+void bbc_ramdisc_device::fred_w(offs_t offset, uint8_t data)
+{
+ if (m_power->read())
+ {
+ switch (offset)
+ {
+ case 0xc0:
+ /* sector LSB */
+ m_sector = (m_sector & 0xff00) | data;
+ break;
+ case 0xc2:
+ /* sector MSB */
+ m_sector = (m_sector & 0x00ff) | (data << 8);
+ break;
+ case 0xc1:
+ case 0xc3:
+ /* TODO: unknown purpose, always writes 0x00 or 0xff */
+ logerror("Write %04x <- %02x\n", offset | 0xfcc0, data);
+ break;
+ }
+ }
+
+ m_1mhzbus->fred_w(offset, data);
+}
+
+uint8_t bbc_ramdisc_device::jim_r(offs_t offset)
+{
+ uint8_t data = 0xff;
+
+ /* power on and sector < 2mb */
+ if (m_power->read() && m_sector < RAM_SIZE)
+ {
+ data &= m_ram[(m_sector << 8) | offset];
+ }
+
+ data &= m_1mhzbus->jim_r(offset);
+
+ return data;
+}
+
+void bbc_ramdisc_device::jim_w(offs_t offset, uint8_t data)
+{
+ /* power on and sector < 2mb */
+ if (m_power->read() && m_sector < RAM_SIZE)
+ {
+ m_ram[(m_sector << 8) | offset] = data;
+ }
+
+ m_1mhzbus->jim_w(offset, data);
+}