// license:BSD-3-Clause
// copyright-holders:AJR
/***************************************************************************
GI ER1400 1400 Bit Serial Electrically Alterable Read-Only Memory
This device uses negative logic. The emulation uses logic levels for
all data, which means that inputs should be inverted if non-inverting
drivers are used and vice versa.
Vgg should be 35 volts below Vss. Logic one is output as 12 volts below
Vss. Vss represents logic zero, which is nominally GND but may be +12V.
The frequency of the input clock should be between 10 kHz and 17 kHz,
with a 35–65% duty cycle when the device is in operation. The clock may
be left at logic zero when the device is in standby.
Write and erase times are 10 ms (min), 15 ms (typical), 24 ms (max).
The data retention capability of the actual chip can be greatly
degraded by frequent reprogramming.
***************************************************************************/
#include "emu.h"
#include "machine/er1400.h"
#define VERBOSE 0
#include "logmacro.h"
// device type definition
DEFINE_DEVICE_TYPE(ER1400, er1400_device, "er1400", "ER1400 Serial EAROM (100x14)")
//**************************************************************************
// ER1400 DEVICE
//**************************************************************************
//-------------------------------------------------
// er1400_device - constructor
//-------------------------------------------------
er1400_device::er1400_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
: device_t(mconfig, ER1400, tag, owner, clock)
, device_nvram_interface(mconfig, *this)
, m_default_data(*this, DEVICE_SELF)
, m_clock_input(0)
, m_code_input(0)
, m_data_input(0)
, m_data_output(0)
, m_write_time(attotime::never)
, m_erase_time(attotime::never)
, m_data_register(0)
, m_address_register(0)
{
}
//-------------------------------------------------
// device_start - device-specific startup
//-------------------------------------------------
void er1400_device::device_start()
{
save_item(NAME(m_clock_input));
save_item(NAME(m_code_input));
save_item(NAME(m_data_input));
save_item(NAME(m_data_output));
save_item(NAME(m_write_time));
save_item(NAME(m_erase_time));
save_item(NAME(m_data_register));
save_item(NAME(m_address_register));
m_data_array = std::make_unique<u16[]>(100);
save_pointer(NAME(m_data_array), 100);
m_data_propagation_timer = timer_alloc(FUNC(er1400_device::propagate_data), this);
}
//-------------------------------------------------
// nvram_default - called to initialize NVRAM to
// its default state
//-------------------------------------------------
void er1400_device::nvram_default()
{
if (m_default_data.found())
{
// obtain default data from memory region
std::copy_n(&m_default_data[0], 100, &m_data_array[0]);
}
else
{
// all locations erased
std::fill_n(&m_data_array[0], 100, 0);
}
}
//-------------------------------------------------
// nvram_read - called to read NVRAM from the
// .nv file
//-------------------------------------------------
bool er1400_device::nvram_read(util::read_stream &file)
{
size_t const size = 100 * sizeof(m_data_array[0]);
auto const [err, actual] = read(file, &m_data_array[0], size);
return !err && (actual == size);
}
//-------------------------------------------------
// nvram_write - called to write NVRAM to the
// specified file
//-------------------------------------------------
bool er1400_device::nvram_write(util::write_stream &file)
{
size_t const size = 100 * sizeof(m_data_array[0]);
auto const [err, actual] = write(file, &m_data_array[0], size);
return !err;
}
//-------------------------------------------------
// address_binary_format - logging helper
//-------------------------------------------------
std::string er1400_device::address_binary_format() const
{
std::ostringstream result;
for (int i = 19; i >= 10; i--)
result << (BIT(m_address_register, i) ? '1' : '0');
result << ':';
for (int i = 9; i >= 0; i--)
result << (BIT(m_address_register, i) ? '1' : '0');
return result.str();
}
//-------------------------------------------------
// read_data - read addressed word into data
// register
//-------------------------------------------------
void er1400_device::read_data()
{
int selected = 0;
m_data_register = 0;
for (int tens = 10; tens < 20; tens++)
{
if (BIT(m_address_register, tens))
{
for (int units = 0; units < 10; units++)
{
if (BIT(m_address_register, units))
{
offs_t offset = 10 * (tens - 10) + units;
LOG("Reading data at %d (%04X) into register\n", offset, m_data_array[offset]);
m_data_register |= m_data_array[offset];
selected++;
}
}
}
}
if (selected != 1)
logerror("%d addresses selected for read operation\n", selected);
}
//-------------------------------------------------
// write_data - write data register to addressed
// word (which must have been erased first)
//-------------------------------------------------
void er1400_device::write_data()
{
int selected = 0;
for (int tens = 10; tens < 20; tens++)
{
if (BIT(m_address_register, tens))
{
for (int units = 0; units < 10; units++)
{
if (BIT(m_address_register, units))
{
offs_t offset = 10 * (tens - 10) + units;
if ((~m_data_array[offset] & m_data_register) != 0)
{
LOG("Writing data at %d (%04X changed to %04X)\n", offset,
m_data_array[offset], m_data_array[offset] & m_data_register);
m_data_array[offset] |= m_data_register;
}
selected++;
}
}
}
}
if (selected != 1)
logerror("%d addresses selected for write operation\n", selected);
}
//-------------------------------------------------
// erase_data - erase data at addressed word to
// all ones
//-------------------------------------------------
void er1400_device::erase_data()
{
int selected = 0;
for (int tens = 10; tens < 20; tens++)
{
if (BIT(m_address_register, tens))
{
for (int units = 0; units < 10; units++)
{
if (BIT(m_address_register, units))
{
offs_t offset = 10 * (tens - 10) + units;
if (m_data_array[offset] != 0)
{
LOG("Erasing data at %d\n", offset);
m_data_array[offset] = 0;
}
selected++;
}
}
}
}
if (selected != 1)
logerror("%d addresses selected for erase operation\n", selected);
}
//-------------------------------------------------
// data_w - write data input line
//-------------------------------------------------
void er1400_device::data_w(int state)
{
m_data_input = bool(state);
}
//-------------------------------------------------
// c1_w - write to first control line
//-------------------------------------------------
void er1400_device::c1_w(int state)
{
if (bool(state) == BIT(m_code_input, 2))
return;
m_code_input = (m_code_input & 3) | (bool(state) << 2);
if (!m_data_propagation_timer->enabled())
m_data_propagation_timer->adjust(attotime::from_usec(20));
}
//-------------------------------------------------
// c2_w - write to second control line
//-------------------------------------------------
void er1400_device::c2_w(int state)
{
if (bool(state) == BIT(m_code_input, 1))
return;
m_code_input = (m_code_input & 5) | (bool(state) << 1);
if (!m_data_propagation_timer->enabled())
m_data_propagation_timer->adjust(attotime::from_usec(20));
}
//-------------------------------------------------
// c3_w - write to third control line
//-------------------------------------------------
void er1400_device::c3_w(int state)
{
if (bool(state) == BIT(m_code_input, 0))
return;
m_code_input = (m_code_input & 6) | bool(state);
if (!m_data_propagation_timer->enabled())
m_data_propagation_timer->adjust(attotime::from_usec(20));
}
//-------------------------------------------------
// propagate_data - clock data out from the chip
//-------------------------------------------------
TIMER_CALLBACK_MEMBER(er1400_device::propagate_data)
{
if (m_code_input == 5)
{
m_data_output = BIT(m_data_register, 13);
LOG("Data output %d bit\n", m_data_output);
}
else
m_data_output = false;
}
//-------------------------------------------------
// clock_w - write to clock line
//-------------------------------------------------
void er1400_device::clock_w(int state)
{
if (m_clock_input == bool(state))
return;
m_clock_input = bool(state);
// Commands are clocked by a logical 1 -> 0 transition (i.e. rising edge)
if (state)
{
if (machine().time() >= m_write_time)
write_data();
if (m_code_input != 6)
{
if (m_write_time != attotime::never && machine().time() < m_write_time)
logerror("Write not completed in time\n");
m_write_time = attotime::never;
}
if (machine().time() >= m_erase_time)
erase_data();
if (m_code_input != 2)
{
if (m_erase_time != attotime::never && machine().time() < m_erase_time)
logerror("Erase not completed in time\n");
m_erase_time = attotime::never;
}
switch (m_code_input)
{
case 0: // standby
break;
case 1: default: // not used
break;
case 2: // erase
if (m_erase_time == attotime::never)
{
LOG("Entering erase command (address = %s)\n", address_binary_format());
m_erase_time = machine().time() + attotime::from_msec(15);
}
break;
case 3: // accept address
LOG("Accepting address %d bit\n", m_data_input);
m_address_register = (m_address_register << 1) | m_data_input;
m_address_register &= 0xfffff;
break;
case 4: // read
read_data();
break;
case 5: // shift data out
m_data_register = (m_data_register & 0x1fff) << 1;
m_data_propagation_timer->adjust(attotime::from_usec(20));
break;
case 6: // write
if (m_write_time == attotime::never)
{
LOG("Entering write command (address = %s, data = %04X)\n", address_binary_format(), m_data_register);
m_write_time = machine().time() + attotime::from_msec(15);
}
break;
case 7: // accept data
LOG("Accepting data %d bit\n", m_data_input);
m_data_register = (m_data_register & 0x1fff) << 1;
m_data_register |= m_data_input;
break;
}
}
}
//-------------------------------------------------
// data_r - read data line
//-------------------------------------------------
int er1400_device::data_r()
{
return m_data_input & m_data_output;
}