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+// license:BSD-3-Clause
+// copyright-holders:Fabio Priuli
+/***********************************************************************************************************
+
+
+ Bally Astrocade RAM expansion emulation
+
+ RAM Expansions (info below courtesy of Paul Thacker)
+
+ Several third party RAM expansions have been made for the Astrocade. These
+ allow access to various ranges of the expansion memory ($5000 to $FFFF).
+ A RAM expansion is required to use extended BASIC programs like Blue RAM BASIC
+ and VIPERSoft BASIC. All of the expansions also have a RAM protect switch, which
+ can be flipped at any time to make the RAM act like ROM. Extended BASIC
+ programs need access to the RAM and won't work with RAM protect enabled, but
+ this can be useful with Bally and Astrocade BASIC. They also have a range switch
+ (not implemented). The default position is 6K, but it can be switched to
+ 2K. This means that the expanded memory starting at $6000 will instead be
+ mapped to the cartridge memory starting at $2000. So it would be possible to
+ load a cartridge program from tape into the expansion memory, then flip the range
+ switch and run it as a cartridge. This is useful for cartridge development.
+
+ Blue RAM -- available in 4K, 16K, and 32K. These also use an INS8154 chip,
+ (not yet implemented) which has an additional $80 bytes of RAM mapped
+ immediately after the end of the expansion address space. This memory
+ can't be write protected. The INS8154 has I/O features needed for loading
+ tape programs into Blue RAM BASIC, as well as running the Blue RAM Utility cart.
+ 4K: $6000 to $6FFF (can't run VIPERSoft BASIC, because this program needs memory
+ past this range)
+ 16K: $6000 to $9FFF
+ 32K: $6000 to $DFFF
+
+ VIPER System 1 -- This is available in 16K only. It also includes a keyboard (not implemented).
+ 16K: $6000 to $9FFF
+
+ Lil' WHITE RAM -- This is available in 32K only. Attempts to read and write
+ to memory outside of its address range ($D000 to $FFFF) are mapped to the expansion
+ memory $5000 to $7FFF. The current implementation won't allow the shadow RAM area
+ to be accessed when RAM protect is on, but there is no known software that will
+ access the upper range of the expansion RAM when RAM protect is enabled.
+ 32K: $5000 to $CFFF
+
+ R&L 64K RAM Board -- This is a highly configurable kit. RAM can be installed in
+ 2K increments. So, the entire 44K expansion memory can be filled. It is also
+ possible to override the rest of the memory map with RAM (not implemented).
+ There are 32 switches allowing users to activate and deactivate each 2K block (not implemented).
+ RAM write protection can be implemented in three ranges through jumpers or by
+ installing switches. The ranges are $0000 to $0FFF (first 4K), $0000 to $3FFF (first 16K),
+ and $0000 to $FFFF (all 64K). The current implementation is for 44K expansion memory mapped from
+ $5000 to $FFFF, with only a single write protect covering this entire range.
+
+ ***********************************************************************************************************/
+
+
+#include "emu.h"
+#include "ram.h"
+
+
+//-------------------------------------------------
+// astrocade_rom_device - constructor
+//-------------------------------------------------
+
+const device_type ASTROCADE_BLUERAM_4K = &device_creator<astrocade_blueram_4k_device>;
+const device_type ASTROCADE_BLUERAM_16K = &device_creator<astrocade_blueram_16k_device>;
+const device_type ASTROCADE_BLUERAM_32K = &device_creator<astrocade_blueram_32k_device>;
+const device_type ASTROCADE_VIPER_SYS1 = &device_creator<astrocade_viper_sys1_device>;
+const device_type ASTROCADE_WHITERAM = &device_creator<astrocade_whiteram_device>;
+const device_type ASTROCADE_RL64RAM = &device_creator<astrocade_rl64ram_device>;
+
+
+astrocade_blueram_4k_device::astrocade_blueram_4k_device(const machine_config &mconfig, device_type type, const char *name, const char *tag, device_t *owner, UINT32 clock, const char *shortname, const char *source)
+ : device_t(mconfig, type, name, tag, owner, clock, shortname, source),
+ device_astrocade_card_interface(mconfig, *this),
+ m_write_prot(*this, "RAM_PROTECT")
+{
+}
+
+astrocade_blueram_4k_device::astrocade_blueram_4k_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
+ : device_t(mconfig, ASTROCADE_BLUERAM_4K, "Bally Astrocade Blue RAM 4K", tag, owner, clock, "astrocade_br4", __FILE__),
+ device_astrocade_card_interface(mconfig, *this),
+ m_write_prot(*this, "RAM_PROTECT")
+{
+}
+
+astrocade_blueram_16k_device::astrocade_blueram_16k_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
+ : astrocade_blueram_4k_device(mconfig, ASTROCADE_BLUERAM_16K, "Bally Astrocade Blue RAM 16K", tag, owner, clock, "astrocade_br16", __FILE__)
+{
+}
+
+astrocade_blueram_32k_device::astrocade_blueram_32k_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
+ : astrocade_blueram_4k_device(mconfig, ASTROCADE_BLUERAM_32K, "Bally Astrocade Blue RAM 32K", tag, owner, clock, "astrocade_br32", __FILE__)
+{
+}
+
+astrocade_viper_sys1_device::astrocade_viper_sys1_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
+ : device_t(mconfig, ASTROCADE_VIPER_SYS1, "Bally Astrocade Viper System 1", tag, owner, clock, "astrocade_vs1", __FILE__),
+ device_astrocade_card_interface(mconfig, *this),
+ m_write_prot(*this, "RAM_PROTECT")
+{
+}
+
+astrocade_whiteram_device::astrocade_whiteram_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
+ : device_t(mconfig, ASTROCADE_WHITERAM, "Bally Astrocade Lil' White RAM 32K", tag, owner, clock, "astrocade_lwr", __FILE__),
+ device_astrocade_card_interface(mconfig, *this),
+ m_write_prot(*this, "RAM_PROTECT")
+{
+}
+
+astrocade_rl64ram_device::astrocade_rl64ram_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
+ : device_t(mconfig, ASTROCADE_RL64RAM, "Bally Astrocade R&L RAM 64K", tag, owner, clock, "astrocade_rl64", __FILE__),
+ device_astrocade_card_interface(mconfig, *this),
+ m_write_prot(*this, "RAM_PROTECT")
+{
+}
+
+
+//-------------------------------------------------
+// RAM Write protect switch
+//-------------------------------------------------
+
+static INPUT_PORTS_START( exp_switches )
+ PORT_START("RAM_PROTECT")
+ PORT_CONFNAME( 0x01, 0x00, "Write Protect RAM")
+ PORT_CONFSETTING( 0x00, DEF_STR(Off))
+ PORT_CONFSETTING( 0x01, DEF_STR(On))
+INPUT_PORTS_END
+
+
+ioport_constructor astrocade_blueram_4k_device::device_input_ports() const
+{
+ return INPUT_PORTS_NAME( exp_switches );
+}
+
+ioport_constructor astrocade_viper_sys1_device::device_input_ports() const
+{
+ return INPUT_PORTS_NAME( exp_switches );
+}
+
+ioport_constructor astrocade_whiteram_device::device_input_ports() const
+{
+ return INPUT_PORTS_NAME( exp_switches );
+}
+
+ioport_constructor astrocade_rl64ram_device::device_input_ports() const
+{
+ return INPUT_PORTS_NAME( exp_switches );
+}
+
+/*-------------------------------------------------
+ specific handlers
+ -------------------------------------------------*/
+
+// Blue RAM expansions have RAM starting at 0x6000, up to the RAM size
+READ8_MEMBER(astrocade_blueram_4k_device::read)
+{
+ if (offset >= 0x1000 && offset < 0x1000 + m_ram.size())
+ return m_ram[offset - 0x1000];
+ else
+ return 0;
+}
+
+WRITE8_MEMBER(astrocade_blueram_4k_device::write)
+{
+ if (offset >= 0x1000 && offset < 0x1000 + m_ram.size() && !m_write_prot->read())
+ m_ram[offset - 0x1000] = data;
+}
+
+
+
+// Viper System 1 expansion has RAM in 0x6000-0x9fff
+READ8_MEMBER(astrocade_viper_sys1_device::read)
+{
+ if (offset >= 0x1000 && offset < 0xa000)
+ return m_ram[offset - 0x1000];
+ else
+ return 0;
+}
+
+WRITE8_MEMBER(astrocade_viper_sys1_device::write)
+{
+ if (offset >= 0x1000 && offset < 0xa000 && !m_write_prot->read())
+ m_ram[offset - 0x1000] = data;
+}
+
+
+
+// Lil' WHITE RAM expansion has RAM in 0x5000-0xcfff + a mirror of the first 0x3000 bytes up to 0xffff
+READ8_MEMBER(astrocade_whiteram_device::read)
+{
+ return m_ram[offset % 0x8000];
+}
+
+WRITE8_MEMBER(astrocade_whiteram_device::write)
+{
+ if (!m_write_prot->read())
+ m_ram[offset % 0x8000] = data;
+}
+
+
+
+// R&L 64K RAM Board (44KB installed) has RAM in 0x5000-0xffff
+READ8_MEMBER(astrocade_rl64ram_device::read)
+{
+ return m_ram[offset];
+}
+
+WRITE8_MEMBER(astrocade_rl64ram_device::write)
+{
+ if (!m_write_prot->read())
+ m_ram[offset] = data;
+}