1 // license:BSD-3-Clause
2 // copyright-holders:Nathan Woods
3 /***************************************************************************
4
5 coco_orch90.cpp
6
7 Code for emulating the CoCo Orch-90 (Orchestra 90) sound cartridge
8
9 The Orch-90 was a simple sound cartridge; it had two 8-bit DACs
10 supporting stereo sound. The left channel was at $FF7A, and the right
11 channel was at $FF7B
12
13
14 Hidden Code exists in the ORCH-90 to produce a higher quality output.
15 Once you start the PAK, hit "SHIFT+ENTER" at the title screen. Once you
16 are at command, type the following (playing the William Tell default):
17 "S" + "ENTER"
18 "P" + "SHIFT+ENTER"
19
20 The output will be cleaner due to code causing a change in CPU speed by
21 addressing CPU registers to run the 6809 at 2x speed.
22
23 "P" + "ENTER" will play at regular CPU speed. The difference should be
24 very noticeable.
25
26 ***************************************************************************/
27
28 #include "emu.h"
29 #include "coco_orch90.h"
30 #include "cococart.h"
31
32 #include "sound/dac.h"
33 #include "speaker.h"
34
35
36 //**************************************************************************
37 // ROM DECLARATIONS
38 //**************************************************************************
39
40 ROM_START(coco_orch90)
41 ROM_REGION(0x2000, "eprom", ROMREGION_ERASE00)
42 ROM_LOAD("orchestra 90,1984,26 - 3143,tandy.rom", 0x0000, 0x2000, CRC(15fb39af) SHA1(6a20fee9c70b36a6435ac8378f31d5b626017df0))
43 ROM_END
44
45
46 //**************************************************************************
47 // ORCH90 DEVICE CLASS
48 //**************************************************************************
49
50 namespace
51 {
52 // ======================> coco_orch90_device
53
54 class coco_orch90_device :
55 public device_t,
56 public device_cococart_interface
57 {
58 public:
59 // construction/destruction
coco_orch90_device(const machine_config & mconfig,const char * tag,device_t * owner,u32 clock)60 coco_orch90_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
61 : device_t(mconfig, COCO_ORCH90, tag, owner, clock)
62 , device_cococart_interface(mconfig, *this)
63 , m_eprom(*this, "eprom")
64 , m_ldac(*this, "ldac")
65 , m_rdac(*this, "rdac")
66 {
67 }
68
69 // optional information overrides
70 virtual void device_add_mconfig(machine_config &config) override;
71
72 protected:
73 // device-level overrides
device_start()74 virtual void device_start() override
75 {
76 // install handlers
77 install_write_handler(0xFF7A, 0xFF7A, write8smo_delegate(*this, FUNC(coco_orch90_device::write_left)));
78 install_write_handler(0xFF7B, 0xFF7B, write8smo_delegate(*this, FUNC(coco_orch90_device::write_right)));
79
80 // Orch-90 ties CART to Q
81 set_line_value(line::CART, line_value::Q);
82 }
83
device_rom_region() const84 virtual const tiny_rom_entry *device_rom_region() const override
85 {
86 return ROM_NAME(coco_orch90);
87 }
88
89 // CoCo cartridge level overrides
get_cart_base()90 virtual u8 *get_cart_base() override
91 {
92 return m_eprom->base();
93 }
94
get_cart_memregion()95 virtual memory_region *get_cart_memregion() override
96 {
97 return m_eprom;
98 }
99
100 virtual u8 cts_read(offs_t offset) override;
101
102 private:
write_left(u8 data)103 void write_left(u8 data) { m_ldac->write(data); }
write_right(u8 data)104 void write_right(u8 data) { m_rdac->write(data); }
105
106 // internal state
107 required_memory_region m_eprom;
108 required_device<dac_byte_interface> m_ldac;
109 required_device<dac_byte_interface> m_rdac;
110 };
111 };
112
113
114 //**************************************************************************
115 // MACHINE AND ROM DECLARATIONS
116 //**************************************************************************
117
device_add_mconfig(machine_config & config)118 void coco_orch90_device::device_add_mconfig(machine_config &config)
119 {
120 SPEAKER(config, "lspeaker").front_left();
121 SPEAKER(config, "rspeaker").front_right();
122 DAC_8BIT_R2R(config, m_ldac, 0).add_route(ALL_OUTPUTS, "lspeaker", 0.5); // ls374.ic5 + r7 (8x20k) + r9 (8x10k)
123 DAC_8BIT_R2R(config, m_rdac, 0).add_route(ALL_OUTPUTS, "rspeaker", 0.5); // ls374.ic4 + r6 (8x20k) + r8 (8x10k)
124 }
125
126 //-------------------------------------------------
127 // cts_read
128 //-------------------------------------------------
129
cts_read(offs_t offset)130 u8 coco_orch90_device::cts_read(offs_t offset)
131 {
132 return m_eprom->base()[offset & 0x1fff];
133 }
134
135
136 //**************************************************************************
137 // DEVICE DECLARATION
138 //**************************************************************************
139
140 DEFINE_DEVICE_TYPE_PRIVATE(COCO_ORCH90, device_cococart_interface, coco_orch90_device, "coco_orch90", "CoCo Orch-90 PAK")
141