// license:BSD-3-Clause // copyright-holders:Aaron Giles /*************************************************************************** er2055.c GI 512 bit electrically alterable read-only memory. ***************************************************************************/ #include "emu.h" #include "machine/er2055.h" //************************************************************************** // GLOBAL VARIABLES //************************************************************************** // device type definition const device_type ER2055 = &device_creator; static ADDRESS_MAP_START( er2055_map, AS_PROGRAM, 8, er2055_device ) AM_RANGE(0x0000, 0x003f) AM_RAM ADDRESS_MAP_END //************************************************************************** // LIVE DEVICE //************************************************************************** //------------------------------------------------- // er2055_device - constructor //------------------------------------------------- er2055_device::er2055_device(const machine_config &mconfig, std::string tag, device_t *owner, UINT32 clock) : device_t(mconfig, ER2055, "ER2055 EAROM", tag, owner, clock, "er2055", __FILE__), device_memory_interface(mconfig, *this), device_nvram_interface(mconfig, *this), m_space_config("EAROM", ENDIANNESS_BIG, 8, 6, 0, *ADDRESS_MAP_NAME(er2055_map)), m_control_state(0), m_address(0), m_data(0) { } //------------------------------------------------- // device_start - device-specific startup //------------------------------------------------- void er2055_device::device_start() { save_item(NAME(m_control_state)); save_item(NAME(m_address)); save_item(NAME(m_data)); m_control_state = 0; } //------------------------------------------------- // memory_space_config - return a description of // any address spaces owned by this device //------------------------------------------------- const address_space_config *er2055_device::memory_space_config(address_spacenum spacenum) const { return (spacenum == 0) ? &m_space_config : nullptr; } //------------------------------------------------- // nvram_default - called to initialize NVRAM to // its default state //------------------------------------------------- void er2055_device::nvram_default() { // default to all-0xff for (int byte = 0; byte < SIZE_DATA; byte++) m_addrspace[0]->write_byte(byte, 0xff); // populate from a memory region if present if (m_region != nullptr) { if (m_region->bytes() != SIZE_DATA) fatalerror("er2055 region '%s' wrong size (expected size = 0x40)\n", tag().c_str()); if (m_region->bytewidth() != 1) fatalerror("er2055 region '%s' needs to be an 8-bit region\n", tag().c_str()); UINT8 *default_data = m_region->base(); for (int byte = 0; byte < SIZE_DATA; byte++) m_addrspace[0]->write_byte(byte, default_data[byte]); } } //------------------------------------------------- // nvram_read - called to read NVRAM from the // .nv file //------------------------------------------------- void er2055_device::nvram_read(emu_file &file) { UINT8 buffer[SIZE_DATA]; file.read(buffer, sizeof(buffer)); for (int byte = 0; byte < SIZE_DATA; byte++) m_addrspace[0]->write_byte(byte, buffer[byte]); } //------------------------------------------------- // nvram_write - called to write NVRAM to the // .nv file //------------------------------------------------- void er2055_device::nvram_write(emu_file &file) { UINT8 buffer[SIZE_DATA]; for (int byte = 0; byte < SIZE_DATA; byte++) buffer[byte] = m_addrspace[0]->read_byte(byte); file.write(buffer, sizeof(buffer)); } //************************************************************************** // I/O OPERATIONS //************************************************************************** //------------------------------------------------- // set_control - set the control lines; these // must be done simultaneously because the chip // reacts to various combinations //------------------------------------------------- void er2055_device::set_control(UINT8 cs1, UINT8 cs2, UINT8 c1, UINT8 c2, UINT8 ck) { // create a new composite control state UINT8 oldstate = m_control_state; m_control_state = (ck != 0) ? CK : 0; m_control_state |= (c1 != 0) ? C1 : 0; m_control_state |= (c2 != 0) ? C2 : 0; m_control_state |= (cs1 != 0) ? CS1 : 0; m_control_state |= (cs2 != 0) ? CS2 : 0; // if not selected, or if change from previous, we're done if ((m_control_state & (CS1 | CS2)) != (CS1 | CS2) || m_control_state == oldstate) return; // something changed, see what it is based on what mode we're in switch (m_control_state & (C1 | C2)) { // write mode; erasing is required, so we perform an AND against previous // data to simulate incorrect behavior if erasing was not done case 0: m_addrspace[0]->write_byte(m_address, m_addrspace[0]->read_byte(m_address) & m_data); //printf("Write %02X = %02X\n", m_address, m_data); break; // erase mode case C2: m_addrspace[0]->write_byte(m_address, 0xff); //printf("Erase %02X\n", m_address); break; // read mode case C1: if ((oldstate & CK) != 0 && (m_control_state & CK) == 0) { m_data = m_addrspace[0]->read_byte(m_address); //printf("Read %02X = %02X\n", m_address, m_data); } break; } }