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Diffstat (limited to 'src/devices/bus/rs232/mboardd.cpp')
-rw-r--r-- | src/devices/bus/rs232/mboardd.cpp | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/src/devices/bus/rs232/mboardd.cpp b/src/devices/bus/rs232/mboardd.cpp new file mode 100644 index 00000000000..1ec2bdc8c9b --- /dev/null +++ b/src/devices/bus/rs232/mboardd.cpp @@ -0,0 +1,144 @@ +// license:BSD-3-Clause +// copyright-holders:R. Belmont + +/* + mboardd.cpp - Mockingboard D emulation + by R. Belmont + + The Apple IIc didn't have slots, so Sweet Micro Systems came up with this, a Mockingboard + in a little box that attached to the IIc's modem port. There's nothing special about the + IIc though - with a proper cable, anything that speaks 9600 8N1 RS-232 could drive this + device. + + A decent disassembly of the 6803 firmware is available from the Apple II Documentation Project: + https://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Interface%20Cards/Audio/Sweet%20Microsystems%20Mockingboard/Source%20Code/ + +*/ + +#include "emu.h" +#include "mboardd.h" + +#include "cpu/m6800/m6801.h" +#include "sound/ay8910.h" + +#include "speaker.h" + + +namespace { + +ROM_START(mboardd) + ROM_REGION(0x800, "mbcpu", 0) + ROM_LOAD("mockingboard d rom.bin", 0x000000, 0x000800, CRC(277b1813) SHA1(e8d20f4b59fe867ff76434d35a14d2cbdc8533e3)) +ROM_END + +class mockingboard_d_device : public device_t, public device_rs232_port_interface +{ +public: + mockingboard_d_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock); + + virtual void input_txd(int state) override; + + required_device<m6803_cpu_device> m_cpu; + required_device<ay8913_device> m_ay1; + required_device<ay8913_device> m_ay2; + +protected: + virtual void device_start() override ATTR_COLD; + virtual void device_reset() override ATTR_COLD; + virtual void device_add_mconfig(machine_config &config) override ATTR_COLD; + virtual const tiny_rom_entry *device_rom_region() const override ATTR_COLD; + +private: + u8 p2_r() { return m_rx_state<<3; }; + void p1_w(u8 data); + + void ser_tx_w(int state) { output_rxd(state); } + + void c000_w(u8 data) { m_c000_latch = data; }; + + void m6803_mem(address_map &map) ATTR_COLD; + int m_rx_state; + u8 m_c000_latch; +}; + +mockingboard_d_device::mockingboard_d_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) + : device_t(mconfig, SERIAL_MOCKINGBOARD_D, tag, owner, clock) + , device_rs232_port_interface(mconfig, *this) + , m_cpu(*this, "mbdcpu") + , m_ay1(*this, "ay1") + , m_ay2(*this, "ay2") +{ +} + +void mockingboard_d_device::device_add_mconfig(machine_config &config) +{ + M6803(config, m_cpu, 4.9152_MHz_XTAL); // value reverse-engineered from 9600 baud SCI rate needed + m_cpu->set_addrmap(AS_PROGRAM, &mockingboard_d_device::m6803_mem); + m_cpu->in_p2_cb().set(FUNC(mockingboard_d_device::p2_r)); + m_cpu->out_p1_cb().set(FUNC(mockingboard_d_device::p1_w)); + m_cpu->out_ser_tx_cb().set(FUNC(mockingboard_d_device::ser_tx_w)); + + SPEAKER(config, "speaker", 2).front(); + AY8913(config, m_ay1, 1022727); + m_ay1->add_route(ALL_OUTPUTS, "speaker", 0.5, 0); + AY8913(config, m_ay2, 1022727); + m_ay2->add_route(ALL_OUTPUTS, "speaker", 0.5, 0); +} + +const tiny_rom_entry *mockingboard_d_device::device_rom_region() const +{ + return ROM_NAME(mboardd); +} + +void mockingboard_d_device::device_start() +{ +} + +void mockingboard_d_device::device_reset() +{ + output_dcd(0); + output_dsr(0); + output_cts(0); +} + +void mockingboard_d_device::m6803_mem(address_map &map) +{ + map(0x8000, 0x83ff).ram(); + // SSI-263 at a000/a001 + map(0xc000, 0xc000).w(FUNC(mockingboard_d_device::c000_w)); + map(0xf800, 0xffff).rom().region("mbcpu", 0); +} + +void mockingboard_d_device::input_txd(int state) +{ + m_rx_state = (state & 1); +} + +void mockingboard_d_device::p1_w(u8 data) +{ + if (BIT(data, 3)) + { + m_ay2->address_w(m_c000_latch); + //printf("%02x to AY2 address\n", m_c000_latch); + } + else if (BIT(data, 2)) + { + m_ay2->data_w(m_c000_latch); + //printf("%02x to AY2 data\n", m_c000_latch); + } + else if (BIT(data, 1)) + { + m_ay1->address_w(m_c000_latch); + //printf("%02x to AY1 address\n", m_c000_latch); + } + else if (BIT(data, 0)) + { + m_ay1->data_w(m_c000_latch); + //printf("%02x to AY1 data\n", m_c000_latch); + } +} + +} // anonymous namespace + + +DEFINE_DEVICE_TYPE_PRIVATE(SERIAL_MOCKINGBOARD_D, device_rs232_port_interface, mockingboard_d_device, "mockingboardd", "Sweet Micro Systems Mockingboard D") |