// 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
******************************************************************************/
#include "emu.h"
#include "cpu/m6502/m6502.h"
#include "includes/electron.h"
#include "imagedev/cassette.h"
#include "formats/uef_cas.h"
#include "formats/csw_cas.h"
#include "sound/beep.h"
#include "screen.h"
#include "softlist.h"
#include "speaker.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));
}
void electron_state::electron_mem(address_map &map)
{
map(0x0000, 0x7fff).rw(this, FUNC(electron_state::electron_mem_r), FUNC(electron_state::electron_mem_w)); /* 32KB of RAM */
map(0x8000, 0xbfff).rw(this, FUNC(electron_state::electron_paged_r), FUNC(electron_state::electron_paged_w)); /* Banked ROM pages */
map(0xc000, 0xffff).rw(this, FUNC(electron_state::electron_mos_r), FUNC(electron_state::electron_mos_w)); /* OS ROM */
map(0xfc00, 0xfcff).rw(this, FUNC(electron_state::electron_fred_r), FUNC(electron_state::electron_fred_w)); /* FRED */
map(0xfd00, 0xfdff).rw(this, FUNC(electron_state::electron_jim_r), FUNC(electron_state::electron_jim_w)); /* JIM */
map(0xfe00, 0xfeff).rw(this, FUNC(electron_state::electron_sheila_r), FUNC(electron_state::electron_sheila_w)); /* SHEILA */
}
void electron_state::electron64_opcodes(address_map &map)
{
map(0x0000, 0xffff).r(this, FUNC(electron_state::electron64_fetch_r));
}
INPUT_CHANGED_MEMBER(electron_state::trigger_reset)
{
m_maincpu->set_input_line(INPUT_LINE_RESET, newval ? ASSERT_LINE : CLEAR_LINE);
if (newval)
{
m_exp->reset();
}
}
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(0xA3) 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 INPUT_PORTS_START( electron64 )
PORT_INCLUDE(electron)
PORT_START("MRB")
PORT_CONFNAME(0x03, 0x02, "MRB Mode")
PORT_CONFSETTING(0x00, "Normal")
PORT_CONFSETTING(0x01, "Turbo")
PORT_CONFSETTING(0x02, "64K")
INPUT_PORTS_END
MACHINE_CONFIG_START(electron_state::electron)
MCFG_DEVICE_ADD( "maincpu", M6502, 16_MHz_XTAL/8 )
MCFG_DEVICE_PROGRAM_MAP( electron_mem )
MCFG_SCREEN_ADD("screen", RASTER)
MCFG_SCREEN_RAW_PARAMS(16_MHz_XTAL, 1024, 0, 640, 312, 0, 256)
//MCFG_SCREEN_RAW_PARAMS(16_MHz_XTAL, 1024, 264, 264 + 640, 312, 31, 31 + 256)
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)
SPEAKER(config, "mono").front_center();
MCFG_DEVICE_ADD( "beeper", BEEP, 300 )
MCFG_SOUND_ROUTE( ALL_OUTPUTS, "mono", 1.00 )
MCFG_RAM_ADD(RAM_TAG)
MCFG_RAM_DEFAULT_SIZE("32K")
MCFG_CASSETTE_ADD( "cassette" )
MCFG_CASSETTE_FORMATS(bbc_cassette_formats)
MCFG_CASSETTE_DEFAULT_STATE(CASSETTE_PLAY | CASSETTE_MOTOR_DISABLED)
MCFG_CASSETTE_INTERFACE("electron_cass")
/* expansion port */
MCFG_ELECTRON_EXPANSION_SLOT_ADD("exp", electron_expansion_devices, "plus3", false)
MCFG_ELECTRON_EXPANSION_SLOT_IRQ_HANDLER(INPUTLINE("maincpu", M6502_IRQ_LINE))
MCFG_ELECTRON_EXPANSION_SLOT_NMI_HANDLER(INPUTLINE("maincpu", M6502_NMI_LINE))
/* software lists */
MCFG_SOFTWARE_LIST_ADD("cass_list", "electron_cass")
MCFG_SOFTWARE_LIST_ADD("cart_list", "electron_cart")
MCFG_SOFTWARE_LIST_ADD("flop_list", "electron_flop")
MCFG_SOFTWARE_LIST_ADD("rom_list", "electron_rom")
MACHINE_CONFIG_END
MACHINE_CONFIG_START(electron_state::btm2105)
electron(config);
MCFG_SCREEN_MODIFY("screen")
MCFG_SCREEN_COLOR(rgb_t::amber())
/* expansion port */
MCFG_DEVICE_MODIFY("exp")
MCFG_DEVICE_SLOT_INTERFACE(electron_expansion_devices, "m2105", true)
/* software lists */
MCFG_SOFTWARE_LIST_REMOVE("cass_list")
MACHINE_CONFIG_END
MACHINE_CONFIG_START(electron_state::electron64)
electron(config);
MCFG_DEVICE_MODIFY("maincpu")
MCFG_DEVICE_PROGRAM_MAP(electron_mem)
MCFG_DEVICE_OPCODES_MAP(electron64_opcodes)
MCFG_RAM_MODIFY(RAM_TAG)
MCFG_RAM_DEFAULT_SIZE("64K")
MACHINE_CONFIG_END
/* Electron Rom Load */
ROM_START(electron)
ROM_REGION( 0x4000, "mos", 0 )
ROM_LOAD( "b02_acornos-1.rom", 0x0000, 0x4000, CRC(a0c2cf43) SHA1(a27ce645472cc5497690e4bfab43710efbb0792d) )
ROM_REGION( 0x4000, "basic", 0 )
ROM_LOAD( "basic.rom", 0x0000, 0x4000, CRC(79434781) SHA1(4a7393f3a45ea309f744441c16723e2ef447a281) )
ROM_END
ROM_START(electron64)
ROM_REGION( 0x4000, "mos", 0 )
ROM_LOAD( "os_300.rom", 0x0000, 0x4000, CRC(f80a0cea) SHA1(165e42ff4164a842e56f08ebd420d5027af99fdd) )
ROM_REGION(0x4000, "basic", 0)
ROM_LOAD( "basic.rom", 0x0000, 0x4000, CRC(79434781) SHA1(4a7393f3a45ea309f744441c16723e2ef447a281) )
ROM_END
#define rom_btm2105 rom_electron
/* YEAR NAME PARENT COMPAT MACHINE INPUT CLASS INIT COMPANY FULLNAME FLAGS */
COMP ( 1983, electron, 0, 0, electron, electron, electron_state, empty_init, "Acorn", "Acorn Electron", MACHINE_IMPERFECT_SOUND | MACHINE_IMPERFECT_GRAPHICS )
COMP ( 1985, btm2105, electron, 0, btm2105, electron, electron_state, empty_init, "British Telecom Business Systems", "BT Merlin M2105", MACHINE_NOT_WORKING )
COMP ( 1987, electron64, electron, 0, electron64, electron64, electron_state, empty_init, "Acorn/Slogger", "Acorn Electron (64K Master RAM Board)", MACHINE_IMPERFECT_SOUND | MACHINE_IMPERFECT_GRAPHICS )