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-rw-r--r--src/mame/machine/electron.c417
1 files changed, 417 insertions, 0 deletions
diff --git a/src/mame/machine/electron.c b/src/mame/machine/electron.c
new file mode 100644
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--- /dev/null
+++ b/src/mame/machine/electron.c
@@ -0,0 +1,417 @@
+// license:BSD-3-Clause
+// copyright-holders:Wilbert Pol
+/******************************************************************************
+ 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;
+
+ //logerror( "PC=%04x: keyboard read from paged rom area, address: %04x", activecpu_get_pc(), offset );
+ for (int i = 0; i < 14; i++)
+ {
+ if (!(offset & 1))
+ data |= m_keybd[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()
+{
+ UINT8 *lo_rom, *up_rom;
+ std::string region_tag;
+ memory_region *cart_rom = memregion(region_tag.assign(m_cart->tag()).append(GENERIC_ROM_REGION_TAG).c_str());
+
+ if (cart_rom)
+ up_rom = cart_rom->base();
+ else
+ up_rom = memregion("user1")->base() + 12 * 0x4000;
+ if (cart_rom && cart_rom->bytes() > 0x4000)
+ lo_rom = cart_rom->base() + 0x4000;
+ else
+ lo_rom = memregion("user1")->base();
+
+ membank("bank2")->configure_entries(0, 1, lo_rom, 0x4000);
+ membank("bank2")->configure_entries(1, 11, memregion("user1")->base() + 0x04000, 0x4000);
+ membank("bank2")->configure_entries(12, 1, up_rom, 0x4000);
+ membank("bank2")->configure_entries(13, 3, memregion("user1")->base() + 0x34000, 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 )
+{
+ 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;
+ }
+
+ m_cart->rom_alloc(filesize, GENERIC_ROM8_WIDTH, ENDIANNESS_LITTLE);
+ image.fread(m_cart->get_rom_base(), filesize);
+ return IMAGE_INIT_PASS;
+ }
+ else
+ {
+ 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;
+ }
+
+ m_cart->rom_alloc(upsize + losize, GENERIC_ROM8_WIDTH, ENDIANNESS_LITTLE);
+
+ if (upsize)
+ memcpy(m_cart->get_rom_base(), image.get_software_region("uprom"), upsize);
+
+ if (losize)
+ memcpy(m_cart->get_rom_base() + upsize, image.get_software_region("lorom"), losize);
+
+ return IMAGE_INIT_PASS;
+ }
+}