// 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>;
//-------------------------------------------------
// at28c16_device - constructor
//-------------------------------------------------
at28c16_device::at28c16_device( const machine_config &mconfig, std::string tag, device_t *owner, UINT32 clock )
: device_t(mconfig, AT28C16, "AT28C16", tag, owner, clock, "at28c16", __FILE__),
device_memory_interface(mconfig, *this),
device_nvram_interface(mconfig, *this),
m_a9_12v( 0 ),
m_oe_12v( 0 ),
m_last_write( -1 )
{
}
//-------------------------------------------------
// device_config_complete - perform any
// operations now that the configuration is
// complete
//-------------------------------------------------
void at28c16_device::device_config_complete()
{
m_space_config = address_space_config( "at28c16", ENDIANNESS_BIG, 8, 12, 0, *ADDRESS_MAP_NAME( at28c16_map8 ) );
}
//-------------------------------------------------
// device_validity_check - perform validity checks
// on this device
//-------------------------------------------------
void at28c16_device::device_validity_check(validity_checker &valid) const
{
}
//-------------------------------------------------
// 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) );
}
//-------------------------------------------------
// device_reset - device-specific reset
//-------------------------------------------------
void at28c16_device::device_reset()
{
}
//-------------------------------------------------
// nvram_default - called to initialize NVRAM to
// its default state
//-------------------------------------------------
void at28c16_device::nvram_default()
{
UINT16 default_value = 0xff;
for( offs_t offs = 0; offs < AT28C16_TOTAL_BYTES; offs++ )
{
m_addrspace[ 0 ]->write_byte( offs, default_value );
}
/* populate from a memory region if present */
if( m_region != nullptr )
{
if( m_region->bytes() != AT28C16_DATA_BYTES )
{
fatalerror( "at28c16 region '%s' wrong size (expected size = 0x%X)\n", tag().c_str(), AT28C16_DATA_BYTES );
}
if( m_region->bytewidth() != 1 )
{
fatalerror( "at28c16 region '%s' needs to be an 8-bit region\n", tag().c_str() );
}
UINT8 *default_data = m_region->base();
for( offs_t offs = 0; offs < AT28C16_DATA_BYTES; offs++ )
m_addrspace[ 0 ]->write_byte( offs, default_data[offs] );
}
}
//-------------------------------------------------
// nvram_read - called to read NVRAM from the
// .nv file
//-------------------------------------------------
void at28c16_device::nvram_read( emu_file &file )
{
dynamic_buffer buffer( AT28C16_TOTAL_BYTES );
file.read( &buffer[0], AT28C16_TOTAL_BYTES );
for( offs_t offs = 0; offs < AT28C16_TOTAL_BYTES; offs++ )
{
m_addrspace[ 0 ]->write_byte( offs, buffer[ offs ] );
}
}
//-------------------------------------------------
// nvram_write - called to write NVRAM to the
// .nv file
//-------------------------------------------------
void at28c16_device::nvram_write( emu_file &file )
{
dynamic_buffer buffer ( AT28C16_TOTAL_BYTES );
for( offs_t offs = 0; offs < AT28C16_TOTAL_BYTES; offs++ )
{
buffer[ offs ] = m_addrspace[ 0 ]->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++ )
{
m_addrspace[ 0 ]->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 && m_addrspace[ 0 ]->read_byte( offset ) != data )
{
m_addrspace[ 0 ]->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 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 data = m_addrspace[ 0 ]->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;
}
}