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-rw-r--r--src/devices/bus/pet/64k.c203
1 files changed, 203 insertions, 0 deletions
diff --git a/src/devices/bus/pet/64k.c b/src/devices/bus/pet/64k.c
new file mode 100644
index 00000000000..4bc9c01d596
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+++ b/src/devices/bus/pet/64k.c
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+// license:BSD-3-Clause
+// copyright-holders:Curt Coder
+/**********************************************************************
+
+ Commodore PET 64KB RAM Expansion emulation
+
+**********************************************************************/
+
+#include "64k.h"
+
+
+
+//**************************************************************************
+// DEVICE DEFINITIONS
+//**************************************************************************
+
+const device_type PET_64K = &device_creator<pet_64k_expansion_device>;
+
+
+
+//**************************************************************************
+// INLINE HELPERS
+//**************************************************************************
+
+//-------------------------------------------------
+// read_ram -
+//-------------------------------------------------
+
+inline UINT8 pet_64k_expansion_device::read_ram(offs_t offset)
+{
+ UINT8 data = 0;
+
+ if (offset < 0xc000)
+ {
+ data = m_ram[(BIT(m_ctrl, 2) << 14) | (offset & 0x3fff)];
+ }
+ else
+ {
+ data = m_ram[0x8000 | (BIT(m_ctrl, 3) << 14) | (offset & 0x3fff)];
+ }
+
+ return data;
+}
+
+
+//-------------------------------------------------
+// write_ram -
+//-------------------------------------------------
+
+inline void pet_64k_expansion_device::write_ram(offs_t offset, UINT8 data)
+{
+ if (offset < 0xc000)
+ {
+ if (!BIT(m_ctrl, 0))
+ {
+ m_ram[(BIT(m_ctrl, 2) << 14) | (offset & 0x3fff)] = data;
+ }
+ }
+ else
+ {
+ if (!BIT(m_ctrl, 1))
+ {
+ m_ram[0x8000 | (BIT(m_ctrl, 3) << 14) | (offset & 0x3fff)] = data;
+ }
+ }
+}
+
+
+
+//**************************************************************************
+// LIVE DEVICE
+//**************************************************************************
+
+//-------------------------------------------------
+// pet_64k_expansion_device - constructor
+//-------------------------------------------------
+
+pet_64k_expansion_device::pet_64k_expansion_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) :
+ device_t(mconfig, PET_64K, "PET 64KB RAM", tag, owner, clock, "pet_64k", __FILE__),
+ device_pet_expansion_card_interface(mconfig, *this),
+ m_ram(*this, "ram"),
+ m_ctrl(0)
+{
+}
+
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void pet_64k_expansion_device::device_start()
+{
+ // allocate memory
+ m_ram.allocate(0x10000);
+
+ // state saving
+ save_item(NAME(m_ctrl));
+}
+
+
+//-------------------------------------------------
+// device_reset - device-specific reset
+//-------------------------------------------------
+
+void pet_64k_expansion_device::device_reset()
+{
+ m_ctrl = 0;
+}
+
+
+//-------------------------------------------------
+// pet_norom_r - NO ROM read
+//-------------------------------------------------
+
+int pet_64k_expansion_device::pet_norom_r(address_space &space, offs_t offset, int sel)
+{
+ return !BIT(m_ctrl, 7);
+}
+
+
+//-------------------------------------------------
+// pet_bd_r - buffered data read
+//-------------------------------------------------
+
+UINT8 pet_64k_expansion_device::pet_bd_r(address_space &space, offs_t offset, UINT8 data, int &sel)
+{
+ if (BIT(m_ctrl, 7))
+ {
+ switch (sel)
+ {
+ case pet_expansion_slot_device::SEL8:
+ if (!BIT(m_ctrl, 5))
+ {
+ data = read_ram(offset);
+ sel = pet_expansion_slot_device::SEL_NONE;
+ }
+ break;
+
+ case pet_expansion_slot_device::SELE:
+ if (!BIT(m_ctrl, 6) || !BIT(offset, 11))
+ {
+ data = read_ram(offset);
+ sel = pet_expansion_slot_device::SEL_NONE;
+ }
+ break;
+
+ case pet_expansion_slot_device::SEL9:
+ case pet_expansion_slot_device::SELA:
+ case pet_expansion_slot_device::SELB:
+ case pet_expansion_slot_device::SELC:
+ case pet_expansion_slot_device::SELD:
+ case pet_expansion_slot_device::SELF:
+ data = read_ram(offset);
+ break;
+ }
+ }
+
+ return data;
+}
+
+
+//-------------------------------------------------
+// pet_bd_w - buffered data write
+//-------------------------------------------------
+
+void pet_64k_expansion_device::pet_bd_w(address_space &space, offs_t offset, UINT8 data, int &sel)
+{
+ if (BIT(m_ctrl, 7))
+ {
+ switch (sel)
+ {
+ case pet_expansion_slot_device::SEL8:
+ if (!BIT(m_ctrl, 5))
+ {
+ write_ram(offset, data);
+ sel = pet_expansion_slot_device::SEL_NONE;
+ }
+ break;
+
+ case pet_expansion_slot_device::SELE:
+ if (!BIT(m_ctrl, 6) || !BIT(offset, 11))
+ {
+ write_ram(offset, data);
+ sel = pet_expansion_slot_device::SEL_NONE;
+ }
+ break;
+
+ case pet_expansion_slot_device::SEL9:
+ case pet_expansion_slot_device::SELA:
+ case pet_expansion_slot_device::SELB:
+ case pet_expansion_slot_device::SELC:
+ case pet_expansion_slot_device::SELD:
+ case pet_expansion_slot_device::SELF:
+ write_ram(offset, data);
+ break;
+ }
+ }
+
+ if (offset == 0xfff0)
+ {
+ m_ctrl = data;
+ }
+}