/******************************************************************************
Acorn Electron driver
MESS Driver By:
Wilbert Pol
******************************************************************************/
#include "emu.h"
#include "includes/electron.h"
#include "sound/beep.h"
#include "imagedev/cassette.h"
void electron_state::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
{
switch (id)
{
case TIMER_TAPE_HANDLER:
electron_tape_timer_handler(ptr, param);
break;
case TIMER_SETUP_BEEP:
setup_beep(ptr, param);
break;
case TIMER_SCANLINE_INTERRUPT:
electron_scanline_interrupt(ptr, param);
break;
default:
assert_always(FALSE, "Unknown id in electron_state::device_timer");
}
}
void electron_state::electron_tape_start()
{
if (m_ula.tape_running )
{
return;
}
m_ula.tape_steps = 0;
m_ula.tape_value = 0x80808080;
m_ula.high_tone_set = 0;
m_ula.bit_count = 0;
m_ula.tape_running = 1;
m_tape_timer->adjust(attotime::zero, 0, attotime::from_hz(4800));
}
void electron_state::electron_tape_stop()
{
m_ula.tape_running = 0;
m_tape_timer->reset();
}
#define TAPE_LOW 0x00;
#define TAPE_HIGH 0xFF;
TIMER_CALLBACK_MEMBER(electron_state::electron_tape_timer_handler)
{
if ( m_ula.cassette_motor_mode )
{
double tap_val;
tap_val = m_cassette->input();
if ( tap_val < -0.5 )
{
m_ula.tape_value = ( m_ula.tape_value << 8 ) | TAPE_LOW;
m_ula.tape_steps++;
}
else if ( tap_val > 0.5 )
{
m_ula.tape_value = ( m_ula.tape_value << 8 ) | TAPE_HIGH;
m_ula.tape_steps++;
}
else
{
m_ula.tape_steps = 0;
m_ula.bit_count = 0;
m_ula.high_tone_set = 0;
m_ula.tape_value = 0x80808080;
}
if ( m_ula.tape_steps > 2 && ( m_ula.tape_value == 0x0000FFFF || m_ula.tape_value == 0x00FF00FF ) )
{
m_ula.tape_steps = 0;
switch( m_ula.bit_count )
{
case 0: /* start bit */
m_ula.start_bit = ( ( m_ula.tape_value == 0x0000FFFF ) ? 0 : 1 );
//logerror( "++ Read start bit: %d\n", m_ula.start_bit );
if ( m_ula.start_bit )
{
if ( m_ula.high_tone_set )
{
m_ula.bit_count--;
}
}
else
{
m_ula.high_tone_set = 0;
}
break;
case 1: case 2: case 3: case 4:
case 5: case 6: case 7: case 8:
//logerror( "++ Read regular bit: %d\n", m_ula.tape_value == 0x0000FFFF ? 0 : 1 );
m_ula.tape_byte = ( m_ula.tape_byte >> 1 ) | ( m_ula.tape_value == 0x0000FFFF ? 0 : 0x80 );
break;
case 9: /* stop bit */
m_ula.stop_bit = ( ( m_ula.tape_value == 0x0000FFFF ) ? 0 : 1 );
//logerror( "++ Read stop bit: %d\n", m_ula.stop_bit );
if ( m_ula.start_bit && m_ula.stop_bit && m_ula.tape_byte == 0xFF && ! m_ula.high_tone_set )
{
electron_interrupt_handler( INT_SET, INT_HIGH_TONE );
m_ula.high_tone_set = 1;
}
else if ( ! m_ula.start_bit && m_ula.stop_bit )
{
//logerror( "-- Byte read from tape: %02x\n", m_ula.tape_byte );
electron_interrupt_handler( INT_SET, INT_RECEIVE_FULL );
}
else
{
logerror( "Invalid start/stop bit combination detected: %d,%d\n", m_ula.start_bit, m_ula.stop_bit );
}
break;
}
m_ula.bit_count = ( m_ula.bit_count + 1 ) % 10;
}
}
}
READ8_MEMBER(electron_state::electron_read_keyboard)
{
UINT8 data = 0;
int i;
static const char *const keynames[] = {
"LINE0", "LINE1", "LINE2", "LINE3", "LINE4", "LINE5", "LINE6",
"LINE7", "LINE8", "LINE9", "LINE10", "LINE11", "LINE12", "LINE13"
};
//logerror( "PC=%04x: keyboard read from paged rom area, address: %04x", activecpu_get_pc(), offset );
for( i = 0; i < 14; i++ )
{
if( !(offset & 1) )
data |= ioport(keynames[i])->read() & 0x0f;
offset = offset >> 1;
}
//logerror( ", data: %02x\n", data );
return data;
}
READ8_MEMBER(electron_state::electron_jim_r)
{
return 0xff;
}
WRITE8_MEMBER(electron_state::electron_jim_w)
{
}
READ8_MEMBER(electron_state::electron_1mhz_r)
{
return 0xff;
}
WRITE8_MEMBER(electron_state::electron_1mhz_w)
{
}
READ8_MEMBER(electron_state::electron_ula_r)
{
UINT8 data = ((UINT8 *)memregion("user1")->base())[0x43E00 + offset];
switch ( offset & 0x0f )
{
case 0x00: /* Interrupt status */
data = m_ula.interrupt_status;
m_ula.interrupt_status &= ~0x02;
break;
case 0x01: /* Unknown */
break;
case 0x04: /* Casette data shift register */
electron_interrupt_handler(INT_CLEAR, INT_RECEIVE_FULL );
data = m_ula.tape_byte;
break;
}
logerror( "ULA: read offset %02x: %02x\n", offset, data );
return data;
}
static const int electron_palette_offset[4] = { 0, 4, 5, 1 };
static const UINT16 electron_screen_base[8] = { 0x3000, 0x3000, 0x3000, 0x4000, 0x5800, 0x5800, 0x6000, 0x5800 };
WRITE8_MEMBER(electron_state::electron_ula_w)
{
int i = electron_palette_offset[(( offset >> 1 ) & 0x03)];
logerror( "ULA: write offset %02x <- %02x\n", offset & 0x0f, data );
switch( offset & 0x0f )
{
case 0x00: /* Interrupt control */
m_ula.interrupt_control = data;
break;
case 0x01: /* Unknown */
break;
case 0x02: /* Screen start address #1 */
m_ula.screen_start = ( m_ula.screen_start & 0x7e00 ) | ( ( data & 0xe0 ) << 1 );
logerror( "screen_start changed to %04x\n", m_ula.screen_start );
break;
case 0x03: /* Screen start addres #2 */
m_ula.screen_start = ( m_ula.screen_start & 0x1c0 ) | ( ( data & 0x3f ) << 9 );
logerror( "screen_start changed to %04x\n", m_ula.screen_start );
break;
case 0x04: /* Cassette data shift register */
break;
case 0x05: /* Interrupt clear and paging */
/* rom page requests are honoured when currently bank 0-7 or 12-15 is switched in,
* or when 8-11 is currently switched in only switching to bank 8-15 is allowed.
*
* Rompages 10 and 11 both select the Basic ROM.
* Rompages 8 and 9 both select the keyboard.
*/
if ( ( ( m_ula.rompage & 0x0C ) != 0x08 ) || ( data & 0x08 ) )
{
m_ula.rompage = data & 0x0f;
if ( m_ula.rompage == 8 || m_ula.rompage == 9 )
{
m_ula.rompage = 8;
space.install_read_handler( 0x8000, 0xbfff, read8_delegate(FUNC(electron_state::electron_read_keyboard),this));
}
else
{
space.install_read_bank( 0x8000, 0xbfff, "bank2");
}
membank("bank2")->set_entry(m_ula.rompage);
}
if ( data & 0x10 )
{
electron_interrupt_handler( INT_CLEAR, INT_DISPLAY_END );
}
if ( data & 0x20 )
{
electron_interrupt_handler( INT_CLEAR, INT_RTC );
}
if ( data & 0x40 )
{
electron_interrupt_handler( INT_CLEAR, INT_HIGH_TONE );
}
if ( data & 0x80 )
{
}
break;
case 0x06: /* Counter divider */
if ( m_ula.communication_mode == 0x01)
{
m_beeper->set_frequency( 1000000 / ( 16 * ( data + 1 ) ) );
}
break;
case 0x07: /* Misc. */
m_ula.communication_mode = ( data >> 1 ) & 0x03;
switch( m_ula.communication_mode )
{
case 0x00: /* cassette input */
m_beeper->set_state( 0 );
electron_tape_start();
break;
case 0x01: /* sound generation */
m_beeper->set_state( 1 );
electron_tape_stop();
break;
case 0x02: /* cassette output */
m_beeper->set_state( 0 );
electron_tape_stop();
break;
case 0x03: /* not used */
m_beeper->set_state( 0 );
electron_tape_stop();
break;
}
m_ula.screen_mode = ( data >> 3 ) & 0x07;
m_ula.screen_base = electron_screen_base[ m_ula.screen_mode ];
m_ula.screen_size = 0x8000 - m_ula.screen_base;
m_ula.vram = (UINT8 *)space.get_read_ptr(m_ula.screen_base );
logerror( "ULA: screen mode set to %d\n", m_ula.screen_mode );
m_ula.cassette_motor_mode = ( data >> 6 ) & 0x01;
m_cassette->change_state(m_ula.cassette_motor_mode ? CASSETTE_MOTOR_ENABLED : CASSETTE_MOTOR_DISABLED, CASSETTE_MOTOR_DISABLED );
m_ula.capslock_mode = ( data >> 7 ) & 0x01;
break;
case 0x08: case 0x0A: case 0x0C: case 0x0E:
// video_update
m_ula.current_pal[i+10] = (m_ula.current_pal[i+10] & 0x01) | (((data & 0x80) >> 5) | ((data & 0x08) >> 1));
m_ula.current_pal[i+8] = (m_ula.current_pal[i+8] & 0x01) | (((data & 0x40) >> 4) | ((data & 0x04) >> 1));
m_ula.current_pal[i+2] = (m_ula.current_pal[i+2] & 0x03) | ((data & 0x20) >> 3);
m_ula.current_pal[i] = (m_ula.current_pal[i] & 0x03) | ((data & 0x10) >> 2);
break;
case 0x09: case 0x0B: case 0x0D: case 0x0F:
// video_update
m_ula.current_pal[i+10] = (m_ula.current_pal[i+10] & 0x06) | ((data & 0x08) >> 3);
m_ula.current_pal[i+8] = (m_ula.current_pal[i+8] & 0x06) | ((data & 0x04) >> 2);
m_ula.current_pal[i+2] = (m_ula.current_pal[i+2] & 0x04) | (((data & 0x20) >> 4) | ((data & 0x02) >> 1));
m_ula.current_pal[i] = (m_ula.current_pal[i] & 0x04) | (((data & 0x10) >> 3) | ((data & 0x01)));
break;
}
}
void electron_state::electron_interrupt_handler(int mode, int interrupt)
{
if ( mode == INT_SET )
{
m_ula.interrupt_status |= interrupt;
}
else
{
m_ula.interrupt_status &= ~interrupt;
}
if ( m_ula.interrupt_status & m_ula.interrupt_control & ~0x83 )
{
m_ula.interrupt_status |= 0x01;
m_maincpu->set_input_line(0, ASSERT_LINE );
}
else
{
m_ula.interrupt_status &= ~0x01;
m_maincpu->set_input_line(0, CLEAR_LINE );
}
}
/**************************************
Machine Initialisation functions
***************************************/
TIMER_CALLBACK_MEMBER(electron_state::setup_beep)
{
m_beeper->set_state( 0 );
m_beeper->set_frequency( 300 );
}
void electron_state::machine_reset()
{
membank("bank2")->set_entry(0);
m_ula.communication_mode = 0x04;
m_ula.screen_mode = 0;
m_ula.cassette_motor_mode = 0;
m_ula.capslock_mode = 0;
m_ula.screen_mode = 0;
m_ula.screen_start = 0x3000;
m_ula.screen_base = 0x3000;
m_ula.screen_size = 0x8000 - 0x3000;
m_ula.screen_addr = 0;
m_ula.tape_running = 0;
m_ula.vram = (UINT8 *)m_maincpu->space(AS_PROGRAM).get_read_ptr(m_ula.screen_base);
}
void electron_state::machine_start()
{
membank("bank2")->configure_entries(0, 16, memregion("user1")->base(), 0x4000);
m_ula.interrupt_status = 0x82;
m_ula.interrupt_control = 0x00;
timer_set(attotime::zero, TIMER_SETUP_BEEP);
m_tape_timer = timer_alloc(TIMER_TAPE_HANDLER);
}
DEVICE_IMAGE_LOAD_MEMBER( electron_state, electron_cart )
{
UINT8 *user1 = memregion("user1")->base() + 0x4000;
if (image.software_entry() == NULL)
{
UINT32 filesize = image.length();
if ( filesize != 16384 )
{
image.seterror(IMAGE_ERROR_UNSPECIFIED, "Invalid size. Only size 16384 is supported");
return IMAGE_INIT_FAIL;
}
if (image.fread( user1 + 12 * 16384, filesize) != filesize)
{
image.seterror(IMAGE_ERROR_UNSPECIFIED, "Error loading file");
return IMAGE_INIT_FAIL;
}
return IMAGE_INIT_PASS;
}
int upsize = image.get_software_region_length("uprom");
int losize = image.get_software_region_length("lorom");
if ( upsize != 16384 && upsize != 0 )
{
image.seterror(IMAGE_ERROR_UNSPECIFIED, "Invalid size for uprom");
return IMAGE_INIT_FAIL;
}
if ( losize != 16384 && losize != 0 )
{
image.seterror(IMAGE_ERROR_UNSPECIFIED, "Invalid size for lorom");
return IMAGE_INIT_FAIL;
}
if ( upsize )
{
memcpy( user1 + 12 * 16384, image.get_software_region("uprom"), upsize );
}
if ( losize )
{
memcpy( user1 + 0 * 16384, image.get_software_region("lorom"), losize );
}
return IMAGE_INIT_PASS;
}