// license:BSD-3-Clause // copyright-holders:smf /*************************************************************************** ATMEL AT28C16 16K ( 2K x 8 ) Parallel EEPROM ***************************************************************************/ #include "emu.h" #include "machine/at28c16.h" #define AT28C16_DATA_BYTES ( 0x800 ) #define AT28C16_ID_BYTES ( 0x20 ) #define AT28C16_TOTAL_BYTES ( AT28C16_DATA_BYTES + AT28C16_ID_BYTES ) #define AT28C16_ID_OFFSET ( AT28C16_DATA_BYTES - AT28C16_ID_BYTES ) //************************************************************************** // GLOBAL VARIABLES //************************************************************************** static ADDRESS_MAP_START( at28c16_map8, AS_PROGRAM, 8, at28c16_device ) AM_RANGE(0x0000, 0x081f) AM_RAM ADDRESS_MAP_END //************************************************************************** // LIVE DEVICE //************************************************************************** // device type definition const device_type AT28C16 = &device_creator; //------------------------------------------------- // at28c16_device - constructor //------------------------------------------------- at28c16_device::at28c16_device( const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock ) : device_t(mconfig, AT28C16, "AT28C16", tag, owner, clock, "at28c16", __FILE__), device_memory_interface(mconfig, *this), device_nvram_interface(mconfig, *this), m_space_config("at28c16", ENDIANNESS_BIG, 8, 12, 0, *ADDRESS_MAP_NAME( at28c16_map8 )), m_a9_12v( 0 ), m_oe_12v( 0 ), m_last_write( -1 ), m_default_data(*this, DEVICE_SELF, AT28C16_DATA_BYTES) { } //------------------------------------------------- // memory_space_config - return a description of // any address spaces owned by this device //------------------------------------------------- const address_space_config *at28c16_device::memory_space_config( address_spacenum spacenum ) const { return ( spacenum == 0 ) ? &m_space_config : nullptr; } //------------------------------------------------- // device_start - device-specific startup //------------------------------------------------- void at28c16_device::device_start() { m_write_timer = timer_alloc(0); 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 at28c16_device::nvram_default() { uint16_t default_value = 0xff; for( offs_t offs = 0; offs < AT28C16_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 < AT28C16_DATA_BYTES; offs++ ) space(AS_PROGRAM).write_byte(offs, m_default_data[offs]); } } //------------------------------------------------- // nvram_read - called to read NVRAM from the // .nv file //------------------------------------------------- void at28c16_device::nvram_read( emu_file &file ) { std::vector buffer( AT28C16_TOTAL_BYTES ); file.read( &buffer[0], AT28C16_TOTAL_BYTES ); for( offs_t offs = 0; offs < AT28C16_TOTAL_BYTES; offs++ ) { space(AS_PROGRAM).write_byte( offs, buffer[ offs ] ); } } //------------------------------------------------- // nvram_write - called to write NVRAM to the // .nv file //------------------------------------------------- void at28c16_device::nvram_write( emu_file &file ) { std::vector buffer ( AT28C16_TOTAL_BYTES ); for( offs_t offs = 0; offs < AT28C16_TOTAL_BYTES; offs++ ) { buffer[ offs ] = space(AS_PROGRAM).read_byte( offs ); } file.write( &buffer[0], AT28C16_TOTAL_BYTES ); } //************************************************************************** // READ/WRITE HANDLERS //************************************************************************** WRITE8_MEMBER( at28c16_device::write ) { if( m_last_write >= 0 ) { // logerror( "%s: AT28C16: write( %04x, %02x ) busy\n", machine.describe_context(), offset, data ); } else if( m_oe_12v ) { // logerror( "%s: AT28C16: write( %04x, %02x ) erase\n", machine.describe_context(), offset, data ); if( m_last_write < 0 ) { for( offs_t offs = 0; offs < AT28C16_TOTAL_BYTES; offs++ ) { this->space(AS_PROGRAM).write_byte( offs, 0xff ); } m_last_write = 0xff; m_write_timer->adjust( attotime::from_usec( 200 ) ); } } else { if( m_a9_12v && offset >= AT28C16_ID_OFFSET ) { offset += AT28C16_ID_BYTES; } // logerror( "%s: AT28C16: write( %04x, %02x )\n", machine.describe_context(), offset, data ); 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( 200 ) ); } } } READ8_MEMBER( at28c16_device::read ) { if( m_last_write >= 0 ) { uint8_t data = m_last_write ^ 0x80; // logerror( "%s: AT28C16: read( %04x ) write status %02x\n", machine.describe_context(), offset, data ); return data; } else { if( m_a9_12v && offset >= AT28C16_ID_OFFSET ) { offset += AT28C16_ID_BYTES; } uint8_t data = this->space(AS_PROGRAM).read_byte( offset ); // logerror( "%s: AT28C16: read( %04x ) data %02x\n", machine.describe_context(), offset, data ); return data; } } WRITE_LINE_MEMBER( at28c16_device::set_a9_12v ) { state &= 1; if( m_a9_12v != state ) { // logerror( "%s: AT28C16: set_a9_12v( %d )\n", machine.describe_context(), state ); m_a9_12v = state; } } WRITE_LINE_MEMBER( at28c16_device::set_oe_12v ) { state &= 1; if( m_oe_12v != state ) { // logerror( "%s: AT28C16: set_oe_12v( %d )\n", machine.describe_context(), state ); m_oe_12v = state; } } void at28c16_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr) { switch( id ) { case 0: m_last_write = -1; break; } }