// license:BSD-3-Clause // copyright-holders:Wilbert Pol /****************************************************************************** Acorn Electron driver By Wilbert Pol Hardware Overview ----------------- The Acorn Electron is a budget version of the BBC Micro home computer Basic specs are: 6502 CPU @ 2MHz or 1MHz 32k RAM and 32k ROM Text modes: 20x32, 40x25, 40x32, 80x25, 80x32 Graphics modes: 160x256 (4 or 16 colors), 320x256 (2 or 4 colors), 640x256 (2 colors), 320x200 (2 colors), 640x200 (2 colors) Colors: 8 colors (either solid or flashing) Sound: 1 channel, 7 octaves; built-in speaker Internal ports for cassette storage, RGB/CVBS monitors and TV output Various expansions can be added via the rear expansion port PCB Layout ---------- |-------------------| |--------| EXPANSION PORT | |-----|---------------------| |---||---------| |MOD | SPKR 16MHz LS169 18VAC|| []18VAC INPUT | |17.7345MHz ROM 18VAC|| POWER | |-----| 74S04 |----| || SUPPLY | | KBD_CONN 6502 |ULA | || | |CVBS |----| || +5VDC | |RGB LS00 LS86 || -5VDC | | PWR|| | |CASS LM324 LS00 LS86 S74 LS74 4164 4164 4164 4164 || | |------------------------------------------------------------||---------| Notes: (all IC's shown. Only 16 ICs are used) 6502 - 6502 CPU, clock input 2.000MHz [16/8] ULA - Custom logic chip 12CO21, also containing most of the BBC Micro circuitry Early PCB revisions used a PLCC68 chip in a socket. Later revisions used a PGA68 chip soldered directly into the motherboard 4164 - 4164 64k x4-bit DRAM (4 chips for 32kbytes total) ROM - Hitachi HN613256 32k x8-bit MASK ROM containing OS & BASIC LM324 - Texas Instruments LM324 Operational Amplifier MOD - UHF TV modulator UM1233-E36 CVBS - Composite color video output socket RGB - RGB monitor video output socket CASS - Cassette port PWR - 3-pin power input from internal power supply KBD_CONN - 22-pin keyboard connector SPKR - 2-pin internal speaker connector ****************************************************************************** Emulation notes: I don't have a real system to verify the behaviour of the emulation. The things that can be done through BASIC programs seem to behave properly (most of the time :). Incomplete: - Sound (sound is too high?) - Graphics (seems to be wrong for several games) - 1 MHz bus is not emulated - Bus claiming by ULA is not implemented - Currently the cartridge support always loads the upper rom in page 12 and the lower rom in page 0. This might need further documentation in the software list and loading code. Missing: - Support for floppy disks - Other peripherals ******************************************************************************/ #include "emu.h" #include "cpu/m6502/m6502.h" #include "includes/electron.h" #include "imagedev/cassette.h" #include "formats/uef_cas.h" #include "sound/beep.h" #include "softlist.h" static const rgb_t electron_palette[8]= { rgb_t(0x0ff,0x0ff,0x0ff), rgb_t(0x000,0x0ff,0x0ff), rgb_t(0x0ff,0x000,0x0ff), rgb_t(0x000,0x000,0x0ff), rgb_t(0x0ff,0x0ff,0x000), rgb_t(0x000,0x0ff,0x000), rgb_t(0x0ff,0x000,0x000), rgb_t(0x000,0x000,0x000) }; PALETTE_INIT_MEMBER(electron_state, electron) { palette.set_pen_colors(0, electron_palette, ARRAY_LENGTH(electron_palette)); } static ADDRESS_MAP_START(electron_mem, AS_PROGRAM, 8, electron_state ) AM_RANGE(0x0000, 0x7fff) AM_RAM AM_REGION("maincpu", 0x00000) /* 32KB of RAM */ AM_RANGE(0x8000, 0xbfff) AM_ROMBANK("bank2") /* Banked ROM pages */ AM_RANGE(0xc000, 0xfbff) AM_ROM AM_REGION("user1", 0x40000) /* OS ROM */ AM_RANGE(0xfc00, 0xfcff) AM_READWRITE(electron_fred_r, electron_fred_w ) /* FRED */ AM_RANGE(0xfd00, 0xfdff) AM_READWRITE(electron_jim_r, electron_jim_w ) /* JIM */ AM_RANGE(0xfe00, 0xfeff) AM_READWRITE(electron_sheila_r, electron_sheila_w ) /* SHEILA */ AM_RANGE(0xff00, 0xffff) AM_ROM AM_REGION("user1", 0x43f00) /* OS ROM continued */ ADDRESS_MAP_END INPUT_CHANGED_MEMBER(electron_state::trigger_reset) { m_maincpu->set_input_line(INPUT_LINE_RESET, PULSE_LINE); } static INPUT_PORTS_START( electron ) PORT_START("LINE.0") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("\xE2\x86\x92 | \\") PORT_CODE(KEYCODE_BACKSLASH) PORT_CHAR(UCHAR_MAMEKEY(RIGHT)) PORT_CHAR('|') PORT_CHAR('\\') // on the real keyboard, this would be on the 1st row, the 3rd key after 0 PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("COPY") PORT_CODE(KEYCODE_END) PORT_CHAR(UCHAR_MAMEKEY(F1)) PORT_CHAR('[') PORT_CHAR(']') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_UNUSED) PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_SPACE) PORT_CHAR(' ') PORT_START("LINE.1") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("\xE2\x86\x90 ^ ~") PORT_CODE(KEYCODE_EQUALS) PORT_CHAR(UCHAR_MAMEKEY(LEFT)) PORT_CHAR('^') PORT_CHAR('~') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("\xE2\x86\x93 _ }") PORT_CODE(KEYCODE_CLOSEBRACE) PORT_CHAR(UCHAR_MAMEKEY(DOWN)) PORT_CHAR('_') PORT_CHAR('}') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("RETURN") PORT_CODE(KEYCODE_ENTER) PORT_CHAR(13) PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("DELETE") PORT_CODE(KEYCODE_BACKSPACE) PORT_CHAR(8) PORT_START("LINE.2") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_MINUS) PORT_CHAR('-') PORT_CHAR('=') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("\xE2\x86\x91 \xC2\xA3 {") PORT_CODE(KEYCODE_OPENBRACE) PORT_CHAR(UCHAR_MAMEKEY(UP)) PORT_CHAR('\xA3') PORT_CHAR('{') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_QUOTE) PORT_CHAR(':') PORT_CHAR('*') PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_UNUSED) PORT_START("LINE.3") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_0) PORT_CHAR('0') PORT_CHAR('@') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_P) PORT_CHAR('p') PORT_CHAR('P') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_COLON) PORT_CHAR(';') PORT_CHAR('+') PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_SLASH) PORT_CHAR('/') PORT_CHAR('?') PORT_START("LINE.4") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_9) PORT_CHAR('9') PORT_CHAR(')') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_O) PORT_CHAR('o') PORT_CHAR('O') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_L) PORT_CHAR('l') PORT_CHAR('L') PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_STOP) PORT_CHAR('.') PORT_CHAR('>') PORT_START("LINE.5") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_8) PORT_CHAR('8') PORT_CHAR('(') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_I) PORT_CHAR('i') PORT_CHAR('I') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_K) PORT_CHAR('k') PORT_CHAR('K') PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_COMMA) PORT_CHAR(',') PORT_CHAR('<') PORT_START("LINE.6") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_7) PORT_CHAR('7') PORT_CHAR('\'') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_U) PORT_CHAR('u') PORT_CHAR('U') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_J) PORT_CHAR('j') PORT_CHAR('J') PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_M) PORT_CHAR('m') PORT_CHAR('M') PORT_START("LINE.7") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_6) PORT_CHAR('6') PORT_CHAR('&') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_Y) PORT_CHAR('y') PORT_CHAR('Y') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_H) PORT_CHAR('h') PORT_CHAR('H') PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_N) PORT_CHAR('n') PORT_CHAR('N') PORT_START("LINE.8") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_5) PORT_CHAR('5') PORT_CHAR('%') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_T) PORT_CHAR('t') PORT_CHAR('T') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_G) PORT_CHAR('g') PORT_CHAR('G') PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_B) PORT_CHAR('b') PORT_CHAR('B') PORT_START("LINE.9") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_4) PORT_CHAR('4') PORT_CHAR('$') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_R) PORT_CHAR('r') PORT_CHAR('R') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_F) PORT_CHAR('f') PORT_CHAR('F') PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_V) PORT_CHAR('v') PORT_CHAR('V') PORT_START("LINE.10") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_3) PORT_CHAR('3') PORT_CHAR('#') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_E) PORT_CHAR('e') PORT_CHAR('E') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_D) PORT_CHAR('d') PORT_CHAR('D') PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_C) PORT_CHAR('c') PORT_CHAR('C') PORT_START("LINE.11") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_2) PORT_CHAR('2') PORT_CHAR('"') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_W) PORT_CHAR('w') PORT_CHAR('W') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_S) PORT_CHAR('s') PORT_CHAR('S') PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_X) PORT_CHAR('x') PORT_CHAR('X') PORT_START("LINE.12") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_1) PORT_CHAR('1') PORT_CHAR('!') PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_Q) PORT_CHAR('q') PORT_CHAR('Q') PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_A) PORT_CHAR('a') PORT_CHAR('A') PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_Z) PORT_CHAR('z') PORT_CHAR('Z') PORT_START("LINE.13") PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("ESCAPE") PORT_CODE(KEYCODE_ESC) PORT_CHAR(UCHAR_MAMEKEY(ESC)) PORT_BIT(0x02, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("FUNC") PORT_CODE(KEYCODE_TAB) PORT_CHAR(UCHAR_MAMEKEY(LALT)) PORT_BIT(0x04, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_LCONTROL) PORT_CODE(KEYCODE_RCONTROL) PORT_CHAR(UCHAR_SHIFT_2) PORT_BIT(0x08, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_CODE(KEYCODE_RSHIFT) PORT_CODE(KEYCODE_LSHIFT) PORT_CHAR(UCHAR_SHIFT_1) PORT_START("BRK") /* BREAK */ PORT_BIT(0x01, IP_ACTIVE_HIGH, IPT_KEYBOARD) PORT_NAME("BREAK") PORT_CODE(KEYCODE_F12) PORT_CHAR(UCHAR_MAMEKEY(F12)) PORT_CHANGED_MEMBER(DEVICE_SELF, electron_state, trigger_reset, 0) INPUT_PORTS_END static MACHINE_CONFIG_START( electron, electron_state ) MCFG_CPU_ADD( "maincpu", M6502, XTAL_16MHz/8 ) MCFG_CPU_PROGRAM_MAP( electron_mem) MCFG_SCREEN_ADD("screen", RASTER) MCFG_SCREEN_REFRESH_RATE( 50.08 ) MCFG_SCREEN_SIZE( 640, 312 ) MCFG_SCREEN_VISIBLE_AREA( 0, 640-1, 0, 256-1 ) MCFG_SCREEN_UPDATE_DRIVER(electron_state, screen_update_electron) MCFG_SCREEN_VIDEO_ATTRIBUTES(VIDEO_UPDATE_SCANLINE) MCFG_SCREEN_PALETTE("palette") MCFG_PALETTE_ADD( "palette", 16 ) MCFG_PALETTE_INIT_OWNER(electron_state, electron) MCFG_SPEAKER_STANDARD_MONO( "mono" ) MCFG_SOUND_ADD( "beeper", BEEP, 300 ) MCFG_SOUND_ROUTE( ALL_OUTPUTS, "mono", 1.00 ) MCFG_CASSETTE_ADD( "cassette" ) MCFG_CASSETTE_FORMATS(uef_cassette_formats) MCFG_CASSETTE_DEFAULT_STATE(CASSETTE_PLAY) MCFG_CASSETTE_INTERFACE("electron_cass") MCFG_GENERIC_CARTSLOT_ADD("cartslot", generic_plain_slot, "electron_cart") MCFG_GENERIC_LOAD(electron_state, electron_cart) /* expansion ports */ MCFG_ELECTRON_EXPANSION_SLOT_ADD("exp", electron_expansion_devices, nullptr) /* software lists */ MCFG_SOFTWARE_LIST_ADD("cass_list","electron_cass") MCFG_SOFTWARE_LIST_ADD("cart_list","electron_cart") MACHINE_CONFIG_END /* Electron Rom Load */ ROM_START(electron) ROM_REGION( 0x10000, "maincpu", ROMREGION_ERASEFF ) ROM_REGION( 0x44000, "user1", 0 ) /* OS Rom */ ROM_LOAD( "os.rom", 0x40000, 0x4000, CRC(bf63fb1f) SHA1(a48b8fa0cfb09140e808ac8a187316c605a0b32e) ) /* Os rom */ /* 00000 0 available for cartridges */ /* 04000 1 available for cartridges */ /* 08000 2 available for cartridges */ /* 0c000 3 available for cartridges */ /* 10000 4 available for cartridges */ /* 14000 5 available for cartridges */ /* 18000 6 available for cartridges */ /* 1c000 7 available for cartridges */ /* 20000 8 keyboard */ /* 24000 9 keyboard mirror */ /* 28000 10 Basic rom */ ROM_LOAD( "basic.rom", 0x28000, 0x4000, CRC(79434781) SHA1(4a7393f3a45ea309f744441c16723e2ef447a281) ) /* 2c000 11 Basic rom mirror */ ROM_COPY( "user1", 0x28000, 0x2c000, 0x4000 ) /* 30000 12 available for cartridges with a language ROM */ /* 34000 13 available for cartridges with a language ROM */ /* 38000 14 available for cartridges with a language ROM */ /* 3c000 15 available for cartridges with a language ROM */ ROM_END /* YEAR NAME PARENT COMPAT MACHINE INPUT CLASS INIT COMPANY FULLNAME */ COMP ( 1983, electron, 0, 0, electron, electron, driver_device, 0, "Acorn", "Acorn Electron", MACHINE_IMPERFECT_SOUND | MACHINE_IMPERFECT_GRAPHICS ) //COMP ( 1985, btm2501, electron, 0, electron, electron, driver_device, 0, "British Telecom Business Systems", "Merlin M2501", MACHINE_NOT_WORKING )