diff options
Diffstat (limited to 'src/devices/bus/a2bus/ramcard16k.c')
-rw-r--r-- | src/devices/bus/a2bus/ramcard16k.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/src/devices/bus/a2bus/ramcard16k.c b/src/devices/bus/a2bus/ramcard16k.c new file mode 100644 index 00000000000..a25ba79423f --- /dev/null +++ b/src/devices/bus/a2bus/ramcard16k.c @@ -0,0 +1,170 @@ +// license:BSD-3-Clause +// copyright-holders:R. Belmont +/********************************************************************* + + ramcard16k.c + + Implemention of the Apple II 16K RAM card (aka "language card") + +*********************************************************************/ + +#include "ramcard16k.h" + +/*************************************************************************** + PARAMETERS +***************************************************************************/ + +//************************************************************************** +// GLOBAL VARIABLES +//************************************************************************** + +const device_type A2BUS_RAMCARD16K = &device_creator<a2bus_ramcard_device>; + +/*************************************************************************** + FUNCTION PROTOTYPES +***************************************************************************/ + +//************************************************************************** +// LIVE DEVICE +//************************************************************************** + +a2bus_ramcard_device::a2bus_ramcard_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_a2bus_card_interface(mconfig, *this) +{ +} + +a2bus_ramcard_device::a2bus_ramcard_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : + device_t(mconfig, A2BUS_RAMCARD16K, "Apple II 16K Language Card", tag, owner, clock, "a2ram16k", __FILE__), + device_a2bus_card_interface(mconfig, *this) +{ +} + +//------------------------------------------------- +// device_start - device-specific startup +//------------------------------------------------- + +void a2bus_ramcard_device::device_start() +{ + // set_a2bus_device makes m_slot valid + set_a2bus_device(); + + memset(m_ram, 0, 16*1024); + + save_item(NAME(m_inh_state)); + save_item(NAME(m_ram)); + save_item(NAME(m_dxxx_bank)); + save_item(NAME(m_last_offset)); +} + +void a2bus_ramcard_device::device_reset() +{ + m_inh_state = INH_NONE; + m_dxxx_bank = 0; + m_last_offset = -1; +} + +void a2bus_ramcard_device::do_io(int offset) +{ + int old_inh_state = m_inh_state; + + switch (offset) + { + case 0x1: case 0x3: case 0x9: case 0xb: + if (offset != m_last_offset) + { + m_last_offset = offset; + return; + } + break; + } + m_last_offset = offset; + + m_inh_state = INH_NONE; + m_dxxx_bank = 0; + + if (offset & 0x1) + { + m_inh_state |= INH_WRITE; + } + + switch(offset & 0x03) + { + case 0x00: + case 0x03: + m_inh_state |= INH_READ; + break; + } + + if (!(offset & 8)) + { + m_dxxx_bank = 0x1000; + } + + if (m_inh_state != old_inh_state) + { + recalc_slot_inh(); + } + + #if 0 + printf("LC: new state %c%c dxxx=%04x\n", + (m_inh_state & INH_READ) ? 'R' : 'x', + (m_inh_state & INH_WRITE) ? 'W' : 'x', + m_dxxx_bank); + #endif +} + + +/*------------------------------------------------- + read_c0nx - called for reads from this card's c0nx space +-------------------------------------------------*/ + +UINT8 a2bus_ramcard_device::read_c0nx(address_space &space, UINT8 offset) +{ + do_io(offset & 0xf); + return 0xff; +} + + +/*------------------------------------------------- + write_c0nx - called for writes to this card's c0nx space +-------------------------------------------------*/ + +void a2bus_ramcard_device::write_c0nx(address_space &space, UINT8 offset, UINT8 data) +{ + do_io(offset & 0xf); +} + +UINT8 a2bus_ramcard_device::read_inh_rom(address_space &space, UINT16 offset) +{ + assert(m_inh_state & INH_READ); // this should never happen + + if (offset < 0xe000) + { + return m_ram[(offset & 0xfff) + m_dxxx_bank]; + } + + return m_ram[(offset & 0x1fff) + 0x2000]; +} + +void a2bus_ramcard_device::write_inh_rom(address_space &space, UINT16 offset, UINT8 data) +{ + // are writes enabled? + if (!(m_inh_state & INH_WRITE)) + { + return; + } + + if (offset < 0xe000) + { + m_ram[(offset & 0xfff) + m_dxxx_bank] = data; + return; + } + + m_ram[(offset & 0x1fff) + 0x2000] = data; +} + +int a2bus_ramcard_device::inh_type() +{ + return m_inh_state; +} |