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Diffstat (limited to 'src/mame/drivers/d6800.c')
-rw-r--r-- | src/mame/drivers/d6800.c | 435 |
1 files changed, 435 insertions, 0 deletions
diff --git a/src/mame/drivers/d6800.c b/src/mame/drivers/d6800.c new file mode 100644 index 00000000000..29f9a074051 --- /dev/null +++ b/src/mame/drivers/d6800.c @@ -0,0 +1,435 @@ +// license:BSD-3-Clause +// copyright-holders:Robbbert +/******************************************************************************** + + The Dream 6800 is a CHIP-8 computer roughly modelled on the Cosmac VIP. + It was described in Electronics Australia magazine in 4 articles starting + in May 1979. It has 1k of ROM and 1k of RAM. The video consists of 64x32 + pixels. The keyboard is a hexcode 4x4 matrix, plus a Function key. + + Designed by Michael Bauer, of the Division of Computing and Mathematics + at Deakin University, Australia. + + NOTE that the display only updates after each 4 digits is entered, and + you can't see what you type as you change bytes. This is by design. + + The cassette has no checksum, header or blocks. It is simply a stream + of pulses. The successful loading of a tape is therefore a matter of luck. + + Function keys: + FN 0 - Modify memory - firstly enter a 4-digit address, then 2-digit data + the address will increment by itself, enter the next byte. + FN by itself will step to the next address. + + FN 1 - Tape load. You must have entered the start address at 0002, and + the end address+1 at 0004 (big-endian). + + FN 2 - Tape save. You must have entered the start address at 0002, and + the end address+1 at 0004 (big-endian). + + FN 3 - Run. You must have entered the 4-digit go address first. + + All CHIP-8 programs load at 0x200 (max size 4k), and exec address + is C000. + + Information and programs can be found at http://chip8.com/?page=78 + + +**********************************************************************************/ + + +#include "emu.h" +#include "cpu/m6800/m6800.h" +#include "sound/beep.h" +#include "imagedev/cassette.h" +#include "imagedev/snapquik.h" +#include "sound/wave.h" +#include "machine/6821pia.h" + + +class d6800_state : public driver_device +{ +public: + d6800_state(const machine_config &mconfig, device_type type, const char *tag) + : driver_device(mconfig, type, tag), + m_maincpu(*this, "maincpu"), + m_cass(*this, "cassette"), + m_pia(*this, "pia"), + m_beeper(*this, "beeper"), + m_videoram(*this, "videoram"), + m_io_x0(*this, "X0"), + m_io_x1(*this, "X1"), + m_io_x2(*this, "X2"), + m_io_x3(*this, "X3"), + m_io_y0(*this, "Y0"), + m_io_y1(*this, "Y1"), + m_io_y2(*this, "Y2"), + m_io_y3(*this, "Y3"), + m_io_shift(*this, "SHIFT") { } + + DECLARE_READ8_MEMBER( d6800_cassette_r ); + DECLARE_WRITE8_MEMBER( d6800_cassette_w ); + DECLARE_READ8_MEMBER( d6800_keyboard_r ); + DECLARE_WRITE8_MEMBER( d6800_keyboard_w ); + DECLARE_WRITE_LINE_MEMBER( d6800_screen_w ); + UINT32 screen_update_d6800(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect); + TIMER_DEVICE_CALLBACK_MEMBER(d6800_c); + TIMER_DEVICE_CALLBACK_MEMBER(d6800_p); + DECLARE_QUICKLOAD_LOAD_MEMBER( d6800 ); +protected: + required_device<cpu_device> m_maincpu; + required_device<cassette_image_device> m_cass; + required_device<pia6821_device> m_pia; + required_device<beep_device> m_beeper; + required_shared_ptr<UINT8> m_videoram; + required_ioport m_io_x0; + required_ioport m_io_x1; + required_ioport m_io_x2; + required_ioport m_io_x3; + required_ioport m_io_y0; + required_ioport m_io_y1; + required_ioport m_io_y2; + required_ioport m_io_y3; + required_ioport m_io_shift; +private: + UINT8 m_rtc; + bool m_cb2; + bool m_cassold; + UINT8 m_cass_data[4]; + UINT8 m_portb; + virtual void machine_start(); + virtual void machine_reset(); +}; + + +/* Memory Maps */ + +static ADDRESS_MAP_START( d6800_map, AS_PROGRAM, 8, d6800_state ) + AM_RANGE(0x0000, 0x00ff) AM_RAM + AM_RANGE(0x0100, 0x01ff) AM_RAM AM_SHARE("videoram") + AM_RANGE(0x0200, 0x0fff) AM_RAM + AM_RANGE(0x8010, 0x8013) AM_DEVREADWRITE("pia", pia6821_device, read, write) + AM_RANGE(0xc000, 0xc7ff) AM_MIRROR(0x3800) AM_ROM +ADDRESS_MAP_END + +/* Input Ports */ + +static INPUT_PORTS_START( d6800 ) + PORT_START("X0") + PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_0) PORT_CHAR('0') + PORT_BIT( 0x02, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_1) PORT_CHAR('1') + PORT_BIT( 0x04, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_2) PORT_CHAR('2') + PORT_BIT( 0x08, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_3) PORT_CHAR('3') + PORT_BIT( 0xf0, IP_ACTIVE_LOW, IPT_UNUSED ) + + PORT_START("X1") + PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_4) PORT_CHAR('4') + PORT_BIT( 0x02, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_5) PORT_CHAR('5') + PORT_BIT( 0x04, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_6) PORT_CHAR('6') + PORT_BIT( 0x08, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_7) PORT_CHAR('7') + PORT_BIT( 0xf0, IP_ACTIVE_LOW, IPT_UNUSED ) + + PORT_START("X2") + PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_8) PORT_CHAR('8') + PORT_BIT( 0x02, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_9) PORT_CHAR('9') + PORT_BIT( 0x04, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_A) PORT_CHAR('A') + PORT_BIT( 0x08, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_B) PORT_CHAR('B') + PORT_BIT( 0xf0, IP_ACTIVE_LOW, IPT_UNUSED ) + + PORT_START("X3") + PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_C) PORT_CHAR('C') + PORT_BIT( 0x02, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_D) PORT_CHAR('D') + PORT_BIT( 0x04, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_E) PORT_CHAR('E') + PORT_BIT( 0x08, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_F) PORT_CHAR('F') + PORT_BIT( 0xf0, IP_ACTIVE_LOW, IPT_UNUSED ) + + PORT_START("Y0") + PORT_BIT( 0x0f, IP_ACTIVE_LOW, IPT_UNUSED ) + PORT_BIT( 0x10, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_0) PORT_CHAR('0') + PORT_BIT( 0x20, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_4) PORT_CHAR('4') + PORT_BIT( 0x40, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_8) PORT_CHAR('8') + PORT_BIT( 0x80, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_C) PORT_CHAR('C') + + PORT_START("Y1") + PORT_BIT( 0x0f, IP_ACTIVE_LOW, IPT_UNUSED ) + PORT_BIT( 0x10, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_1) PORT_CHAR('1') + PORT_BIT( 0x20, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_5) PORT_CHAR('5') + PORT_BIT( 0x40, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_9) PORT_CHAR('9') + PORT_BIT( 0x80, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_D) PORT_CHAR('D') + + PORT_START("Y2") + PORT_BIT( 0x0f, IP_ACTIVE_LOW, IPT_UNUSED ) + PORT_BIT( 0x10, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_2) PORT_CHAR('2') + PORT_BIT( 0x20, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_6) PORT_CHAR('6') + PORT_BIT( 0x40, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_A) PORT_CHAR('A') + PORT_BIT( 0x80, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_E) PORT_CHAR('E') + + PORT_START("Y3") + PORT_BIT( 0x0f, IP_ACTIVE_LOW, IPT_UNUSED ) + PORT_BIT( 0x10, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_3) PORT_CHAR('3') + PORT_BIT( 0x20, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_7) PORT_CHAR('7') + PORT_BIT( 0x40, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_B) PORT_CHAR('B') + PORT_BIT( 0x80, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_CODE(KEYCODE_F) PORT_CHAR('F') + + PORT_START("SHIFT") + PORT_BIT( 0x01, IP_ACTIVE_LOW, IPT_KEYBOARD ) PORT_NAME("FN") PORT_CODE(KEYCODE_LSHIFT) + + PORT_START("VS") + /* vblank */ + PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_CUSTOM) PORT_VBLANK("screen") +INPUT_PORTS_END + +/* Video */ + +UINT32 d6800_state::screen_update_d6800(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect) +{ + UINT8 x,y,gfx=0; + + for (y = 0; y < 32; y++) + { + UINT16 *p = &bitmap.pix16(y); + + for (x = 0; x < 8; x++) + { + if (m_cb2) + gfx = m_videoram[ x | (y<<3)]; + + *p++ = BIT(gfx, 7); + *p++ = BIT(gfx, 6); + *p++ = BIT(gfx, 5); + *p++ = BIT(gfx, 4); + *p++ = BIT(gfx, 3); + *p++ = BIT(gfx, 2); + *p++ = BIT(gfx, 1); + *p++ = BIT(gfx, 0); + } + } + return 0; +} + +/* NE556 */ + +TIMER_DEVICE_CALLBACK_MEMBER(d6800_state::d6800_c) +{ + m_cass_data[3]++; + + if (BIT(m_portb, 0) != m_cassold) + { + m_cass_data[3] = 0; + m_cassold = BIT(m_portb, 0); + } + + if (BIT(m_portb, 0)) + m_cass->output(BIT(m_cass_data[3], 0) ? -1.0 : +1.0); // 2400Hz + else + m_cass->output(BIT(m_cass_data[3], 1) ? -1.0 : +1.0); // 1200Hz +} + +/* PIA6821 Interface */ + +TIMER_DEVICE_CALLBACK_MEMBER(d6800_state::d6800_p) +{ + m_rtc++; + if (m_rtc > 159) + m_rtc = 0; + + UINT8 data = m_io_x0->read() & m_io_x1->read() & m_io_x2->read() & m_io_x3->read(); + int ca1 = (data == 255) ? 0 : 1; + int ca2 = m_io_shift->read(); + int cb1 = (m_rtc) ? 1 : 0; + + m_pia->ca1_w(ca1); + m_pia->ca2_w(ca2); + m_pia->cb1_w(cb1); + + /* cassette - turn 1200/2400Hz to a bit */ + m_cass_data[1]++; + UINT8 cass_ws = (m_cass->input() > +0.03) ? 1 : 0; + + if (cass_ws != m_cass_data[0]) + { + m_cass_data[0] = cass_ws; + m_cass_data[2] = ((m_cass_data[1] < 12) ? 128 : 0); + m_cass_data[1] = 0; + } +} + + +WRITE_LINE_MEMBER( d6800_state::d6800_screen_w ) +{ + m_cb2 = state; +} + +READ8_MEMBER( d6800_state::d6800_cassette_r ) +{ + /* + Cassette circuit consists of a 741 op-amp, a 74121 oneshot, and a 74LS74. + When a pulse arrives, the oneshot is set. After a preset time, it triggers + and the 74LS74 compares this pulse to the output of the 741. Therefore it + knows if the tone is 1200 or 2400 Hz. Input to PIA is bit 7. + */ + + return m_cass_data[2] | m_portb; +} + +WRITE8_MEMBER( d6800_state::d6800_cassette_w ) +{ + /* + A NE556 runs at either 1200 or 2400 Hz, depending on the state of bit 0. + This output drives the speaker and the output signal to the cassette player. + Bit 6 enables the speaker. Also the speaker is silenced when cassette operations + are in progress (DMA/CB2 line low). + */ + + m_beeper->set_frequency(BIT(data, 0) ? 2400 : 1200); + m_beeper->set_state(BIT(data, 6) & m_cb2); + + m_portb = data & 0x7f; +} + +READ8_MEMBER( d6800_state::d6800_keyboard_r ) +{ + /* + This system reads the key matrix one way, then swaps the input and output + lines around and reads it another way. This isolates the key that was pressed. + */ + + UINT8 data = m_io_x0->read() & m_io_x1->read() & m_io_x2->read() & m_io_x3->read() + & m_io_y0->read() & m_io_y1->read() & m_io_y2->read() & m_io_y3->read(); + + return data; +} + +WRITE8_MEMBER( d6800_state::d6800_keyboard_w ) +{ + /* + + bit description + + PA0 keyboard column 0 + PA1 keyboard column 1 + PA2 keyboard column 2 + PA3 keyboard column 3 + PA4 keyboard row 0 + PA5 keyboard row 1 + PA6 keyboard row 2 + PA7 keyboard row 3 + + */ + +} + +/* Machine Initialization */ + +void d6800_state::machine_start() +{ +} + +void d6800_state::machine_reset() +{ + m_beeper->set_state(0); + m_rtc = 0; + m_cass_data[0] = 0; + m_cass_data[1] = 0; + m_cass_data[2] = 128; + m_cass_data[3] = 0; +} + +/* Machine Drivers */ + +QUICKLOAD_LOAD_MEMBER( d6800_state, d6800 ) +{ + address_space &space = m_maincpu->space(AS_PROGRAM); + int i; + int quick_addr = 0x200; + int exec_addr = 0xc000; + int quick_length; + dynamic_buffer quick_data; + int read_; + int result = IMAGE_INIT_FAIL; + + quick_length = image.length(); + quick_data.resize(quick_length); + read_ = image.fread( &quick_data[0], quick_length); + if (read_ != quick_length) + { + image.seterror(IMAGE_ERROR_INVALIDIMAGE, "Cannot read the file"); + image.message(" Cannot read the file"); + } + else + { + for (i = 0; i < quick_length; i++) + if ((quick_addr + i) < 0x1000) + space.write_byte(i + quick_addr, quick_data[i]); + + /* display a message about the loaded quickload */ + image.message(" Quickload: size=%04X : start=%04X : end=%04X : exec=%04X",quick_length,quick_addr,quick_addr+quick_length,exec_addr); + + // Start the quickload + if (strcmp(image.filetype(), "bin") == 0) + m_maincpu->set_pc(quick_addr); + else + m_maincpu->set_pc(exec_addr); + + result = IMAGE_INIT_PASS; + } + + return result; +} + +static MACHINE_CONFIG_START( d6800, d6800_state ) + /* basic machine hardware */ + MCFG_CPU_ADD("maincpu",M6800, XTAL_4MHz/4) + MCFG_CPU_PROGRAM_MAP(d6800_map) + + /* video hardware */ + MCFG_SCREEN_ADD("screen", RASTER) + MCFG_SCREEN_REFRESH_RATE(50) + MCFG_SCREEN_SIZE(64, 32) + MCFG_SCREEN_VISIBLE_AREA(0, 63, 0, 31) + MCFG_SCREEN_UPDATE_DRIVER(d6800_state, screen_update_d6800) + MCFG_SCREEN_VBLANK_TIME(ATTOSECONDS_IN_USEC(25)) + MCFG_SCREEN_PALETTE("palette") + + MCFG_PALETTE_ADD_BLACK_AND_WHITE("palette") + + /* sound hardware */ + MCFG_SPEAKER_STANDARD_MONO("mono") + MCFG_SOUND_WAVE_ADD(WAVE_TAG, "cassette") + MCFG_SOUND_ROUTE(ALL_OUTPUTS, "mono", 0.50) + MCFG_SOUND_ADD("beeper", BEEP, 0) + MCFG_SOUND_ROUTE(ALL_OUTPUTS, "mono", 0.50) + + /* devices */ + MCFG_DEVICE_ADD("pia", PIA6821, 0) + MCFG_PIA_READPA_HANDLER(READ8(d6800_state, d6800_keyboard_r)) + MCFG_PIA_READPB_HANDLER(READ8(d6800_state, d6800_cassette_r)) + MCFG_PIA_WRITEPA_HANDLER(WRITE8(d6800_state, d6800_keyboard_w)) + MCFG_PIA_WRITEPB_HANDLER(WRITE8(d6800_state, d6800_cassette_w)) + MCFG_PIA_CB2_HANDLER(WRITELINE(d6800_state, d6800_screen_w)) + MCFG_PIA_IRQA_HANDLER(DEVWRITELINE("maincpu", m6800_cpu_device, irq_line)) + MCFG_PIA_IRQB_HANDLER(DEVWRITELINE("maincpu", m6800_cpu_device, irq_line)) + + MCFG_CASSETTE_ADD("cassette") + MCFG_CASSETTE_DEFAULT_STATE(CASSETTE_STOPPED | CASSETTE_MOTOR_ENABLED | CASSETTE_SPEAKER_MUTED) + + MCFG_TIMER_DRIVER_ADD_PERIODIC("d6800_c", d6800_state, d6800_c, attotime::from_hz(4800)) + MCFG_TIMER_DRIVER_ADD_PERIODIC("d6800_p", d6800_state, d6800_p, attotime::from_hz(40000)) + + /* quickload */ + MCFG_QUICKLOAD_ADD("quickload", d6800_state, d6800, "bin,c8,ch8", 1) +MACHINE_CONFIG_END + +/* ROMs */ + +ROM_START( d6800 ) + ROM_REGION( 0x10000, "maincpu", 0 ) + ROM_SYSTEM_BIOS(0, "0", "Original") + ROMX_LOAD( "d6800.bin", 0xc000, 0x0400, CRC(3f97ca2e) SHA1(60f26e57a058262b30befceceab4363a5d65d877), ROM_BIOS(1) ) + ROMX_LOAD( "d6800.bin", 0xc400, 0x0400, CRC(3f97ca2e) SHA1(60f26e57a058262b30befceceab4363a5d65d877), ROM_BIOS(1) ) + ROM_SYSTEM_BIOS(1, "1", "Dreamsoft") + ROMX_LOAD( "d6800d.bin", 0xc000, 0x0800, CRC(ded5712f) SHA1(f594f313a74d7135c9fdd0bcb0093fc5771a9b7d), ROM_BIOS(2) ) +ROM_END + +/* YEAR NAME PARENT COMPAT MACHINE INPUT CLASS, INIT COMPANY FULLNAME FLAGS */ +COMP( 1979, d6800, 0, 0, d6800, d6800, driver_device, 0, "Michael Bauer", "Dream 6800", 0 ) |