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Diffstat (limited to 'src/devices/machine/at28c64b.cpp')
-rw-r--r-- | src/devices/machine/at28c64b.cpp | 271 |
1 files changed, 271 insertions, 0 deletions
diff --git a/src/devices/machine/at28c64b.cpp b/src/devices/machine/at28c64b.cpp new file mode 100644 index 00000000000..3f0729e018c --- /dev/null +++ b/src/devices/machine/at28c64b.cpp @@ -0,0 +1,271 @@ +// license:BSD-3-Clause +// copyright-holders:smf, R. Belmont +/*************************************************************************** + ATMEL AT28C64B + + 64K ( 8K x 8 ) Parallel EEPROM with flash-like in-band signalling + +***************************************************************************/ + +#include "emu.h" +#include "at28c64b.h" + +static constexpr int AT28C64B_DATA_BYTES = 0x10000; +static constexpr int AT28C64B_ID_BYTES = 0x40; +static constexpr int AT28C64B_TOTAL_BYTES = AT28C64B_DATA_BYTES + AT28C64B_ID_BYTES; + +static constexpr int AT28C64B_ID_OFFSET = 0x1fc0; +static constexpr int AT28C64B_SECTOR_SIZE = 0x40; + + +//************************************************************************** +// GLOBAL VARIABLES +//************************************************************************** + +void at28c64b_device::at28c64b_map8(address_map &map) +{ + map(0x00000, 0x1003f).ram(); +} + + + +//************************************************************************** +// LIVE DEVICE +//************************************************************************** + +// device type definition +DEFINE_DEVICE_TYPE(AT28C64B, at28c64b_device, "at28c64b", "AT28C64B 8Kx8 EEPROM") + +//------------------------------------------------- +// at28c64b_device - constructor +//------------------------------------------------- + +at28c64b_device::at28c64b_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) + : device_t(mconfig, AT28C64B, tag, owner, clock), + device_memory_interface(mconfig, *this), + device_nvram_interface(mconfig, *this), + m_space_config("at28c64b", ENDIANNESS_BIG, 8, 17, 0, address_map_constructor(FUNC(at28c64b_device::at28c64b_map8), this)), + m_a9_12v(0), + m_oe_12v(0), + m_last_write(-1), + m_state(0), + m_bytes_in_sector(0), + m_default_data(*this, DEVICE_SELF) +{ +} + + +//------------------------------------------------- +// memory_space_config - return a description of +// any address spaces owned by this device +//------------------------------------------------- + +device_memory_interface::space_config_vector at28c64b_device::memory_space_config() const +{ + return space_config_vector { + std::make_pair(0, &m_space_config) + }; +} + + +//------------------------------------------------- +// device_start - device-specific startup +//------------------------------------------------- + +void at28c64b_device::device_start() +{ + m_write_timer = timer_alloc( FUNC( at28c64b_device::write_complete ), this ); + + save_item( NAME(m_a9_12v) ); + save_item( NAME(m_oe_12v) ); + save_item( NAME(m_last_write) ); +} + + +//------------------------------------------------- +// nvram_default - called to initialize NVRAM to +// its default state +//------------------------------------------------- + +void at28c64b_device::nvram_default() +{ + uint16_t const default_value = 0xff; + for (offs_t offs = 0; offs < AT28C64B_TOTAL_BYTES; offs++) + space(AS_PROGRAM).write_byte(offs, default_value); + + /* populate from a memory region if present */ + if (m_default_data.found()) + { + for (offs_t offs = 0; offs < m_default_data.length(); offs++) + space(AS_PROGRAM).write_byte(offs, m_default_data[offs]); + } +} + + +//------------------------------------------------- +// nvram_read - called to read NVRAM from the +// .nv file +//------------------------------------------------- + +bool at28c64b_device::nvram_read(util::read_stream &file) +{ + std::vector<uint8_t> buffer(AT28C64B_TOTAL_BYTES); + + auto const [err, actual] = util::read(file, &buffer[0], AT28C64B_TOTAL_BYTES); + if (err || (actual != AT28C64B_TOTAL_BYTES)) + return false; + + for (offs_t offs = 0; offs < AT28C64B_TOTAL_BYTES; offs++) + space(AS_PROGRAM).write_byte(offs, buffer[offs]); + + return true; +} + +//------------------------------------------------- +// nvram_write - called to write NVRAM to the +// .nv file +//------------------------------------------------- + +bool at28c64b_device::nvram_write(util::write_stream &file) +{ + std::vector<uint8_t> buffer(AT28C64B_TOTAL_BYTES); + + for (offs_t offs = 0; offs < AT28C64B_TOTAL_BYTES; offs++) + buffer[offs] = space(AS_PROGRAM).read_byte(offs); + + auto const [err, actual] = util::write(file, &buffer[0], AT28C64B_TOTAL_BYTES); + return !err; +} + + + +//************************************************************************** +// READ/WRITE HANDLERS +//************************************************************************** + +void at28c64b_device::write(offs_t offset, uint8_t data) +{ + logerror("%s: AT28C64B: write( %04x, %02x ) state %d last_write %d\n", machine().describe_context(), offset, data, m_state, m_last_write); + + if (m_state == STATE_SECTOR_WRITE) + { + logerror("SECTOR WRITE: %02x @ %x\n", data, offset); + this->space(AS_PROGRAM).write_byte(offset, data); + m_last_write = data; + m_write_timer->adjust(attotime::from_usec(10)); + m_bytes_in_sector--; + if (m_bytes_in_sector == 0) + { + m_state = STATE_WRITE_PROTECT; + } + return; + } + + if( m_last_write >= 0 ) + { +// logerror( "%s: AT28C64B: write( %04x, %02x ) busy\n", machine().describe_context(), offset, data ); + } + else if( m_oe_12v ) + { +// logerror( "%s: AT28C64B: write( %04x, %02x ) erase\n", machine().describe_context(), offset, data ); + if( m_last_write < 0 ) + { + for( offs_t offs = 0; offs < AT28C64B_TOTAL_BYTES; offs++ ) + { + this->space(AS_PROGRAM).write_byte( offs, 0xff ); + } + + m_last_write = 0xff; + m_write_timer->adjust( attotime::from_usec( 10 ) ); + } + } + else + { + if ((offset == 0x1555) && (data == 0xaa)) + { + m_state = STATE_ID_1; + return; + } + + if ((m_state == STATE_ID_1) && (offset == 0xaaa) && (data == 0x55)) + { + m_state = STATE_ID_2; + return; + } + + if ((m_state == STATE_ID_2) && (offset == 0x1555) && (data == 0xa0)) + { + m_state = STATE_SECTOR_WRITE; + m_bytes_in_sector = AT28C64B_SECTOR_SIZE; + return; + } + + if (m_state == STATE_WRITE_PROTECT) + { + logerror("%s: write %02x to %x while write protected\n", machine().describe_context(), data, offset); + return; + } + + if ((m_a9_12v) && (offset >= AT28C64B_ID_OFFSET) && (offset < (AT28C64B_ID_OFFSET + AT28C64B_ID_BYTES))) + { + offset += AT28C64B_ID_BYTES; + } + + if( m_last_write < 0 && this->space(AS_PROGRAM).read_byte( offset ) != data ) + { + this->space(AS_PROGRAM).write_byte( offset, data ); + m_last_write = data; + m_write_timer->adjust( attotime::from_usec( 10 ) ); + } + } +} + + +uint8_t at28c64b_device::read(offs_t offset) +{ + if( m_last_write >= 0 ) + { + uint8_t data = m_last_write ^ 0x80; +// logerror( "%s: AT28C64B: read( %04x ) write status %02x\n", machine().describe_context(), offset, data ); + return data; + } + else + { + if( m_a9_12v && offset >= AT28C64B_ID_OFFSET ) + { + offset += AT28C64B_ID_BYTES; + } + + uint8_t data = this->space(AS_PROGRAM).read_byte( offset ); +// logerror( "%s: AT28C64B: read( %04x ) data %02x\n", machine().describe_context(), offset, data ); + return data; + } +} + + +void at28c64b_device::set_a9_12v(int state) +{ + state &= 1; + if( m_a9_12v != state ) + { +// logerror( "%s: AT28C64B: set_a9_12v( %d )\n", machine().describe_context(), state ); + m_a9_12v = state; + } +} + + +void at28c64b_device::set_oe_12v(int state) +{ + state &= 1; + if( m_oe_12v != state ) + { +// logerror( "%s: AT28C64B: set_oe_12v( %d )\n", machine().describe_context(), state ); + m_oe_12v = state; + } +} + + +TIMER_CALLBACK_MEMBER( at28c64b_device::write_complete ) +{ + m_last_write = -1; +} |