1 // license:BSD-3-Clause
2 // copyright-holders:Nigel Barnes
3 /**********************************************************************
4 
5     JAFA Systems ROMPlus-144
6 
7 **********************************************************************/
8 
9 
10 #include "emu.h"
11 #include "romp144.h"
12 
13 
14 //**************************************************************************
15 //  DEVICE DEFINITIONS
16 //**************************************************************************
17 
18 DEFINE_DEVICE_TYPE(ELECTRON_ROMP144, electron_romp144_device, "electron_romp144", "JAFA Systems ROMPlus-144")
19 
20 
21 //-------------------------------------------------
22 //  device_add_mconfig - add device configuration
23 //-------------------------------------------------
24 
device_add_mconfig(machine_config & config)25 void electron_romp144_device::device_add_mconfig(machine_config &config)
26 {
27 	/* rom sockets */
28 	GENERIC_SOCKET(config, m_romslot[0], generic_plain_slot, "electron_rom", "bin,rom");
29 	m_romslot[0]->set_device_load(FUNC(electron_romp144_device::rom0));
30 	GENERIC_SOCKET(config, m_romslot[1], generic_plain_slot, "electron_rom", "bin,rom");
31 	m_romslot[1]->set_device_load(FUNC(electron_romp144_device::rom1));
32 	GENERIC_SOCKET(config, m_romslot[2], generic_plain_slot, "electron_rom", "bin,rom");
33 	m_romslot[2]->set_device_load(FUNC(electron_romp144_device::rom2));
34 	GENERIC_SOCKET(config, m_romslot[3], generic_plain_slot, "electron_rom", "bin,rom");
35 	m_romslot[3]->set_device_load(FUNC(electron_romp144_device::rom3));
36 	GENERIC_SOCKET(config, m_romslot[4], generic_plain_slot, "electron_rom", "bin,rom");
37 	m_romslot[4]->set_device_load(FUNC(electron_romp144_device::rom4));
38 	GENERIC_SOCKET(config, m_romslot[5], generic_plain_slot, "electron_rom", "bin,rom");
39 	m_romslot[5]->set_device_load(FUNC(electron_romp144_device::rom5));
40 	GENERIC_SOCKET(config, m_romslot[6], generic_plain_slot, "electron_rom", "bin,rom");
41 	m_romslot[6]->set_device_load(FUNC(electron_romp144_device::rom6));
42 }
43 
44 //**************************************************************************
45 //  LIVE DEVICE
46 //**************************************************************************
47 
48 //-------------------------------------------------
49 //  electron_romp144_device - constructor
50 //-------------------------------------------------
51 
electron_romp144_device(const machine_config & mconfig,const char * tag,device_t * owner,uint32_t clock)52 electron_romp144_device::electron_romp144_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
53 	: device_t(mconfig, ELECTRON_ROMP144, tag, owner, clock)
54 	, device_electron_cart_interface(mconfig, *this)
55 	, m_romslot(*this, "rom%u", 7)
56 {
57 }
58 
59 //-------------------------------------------------
60 //  device_start - device-specific startup
61 //-------------------------------------------------
62 
device_start()63 void electron_romp144_device::device_start()
64 {
65 	m_rom_select = 0xff;
66 	m_rom_latch = 0xff;
67 
68 	save_item(NAME(m_rom_select));
69 	save_item(NAME(m_rom_latch));
70 }
71 
72 //-------------------------------------------------
73 //  read - cartridge data read
74 //-------------------------------------------------
75 
read(offs_t offset,int infc,int infd,int romqa,int oe,int oe2)76 uint8_t electron_romp144_device::read(offs_t offset, int infc, int infd, int romqa, int oe, int oe2)
77 {
78 	uint8_t data = 0xff;
79 
80 	if (oe)
81 	{
82 		if (romqa)
83 		{
84 			if ((m_rom_select & 0x07) == 0x00)
85 				data = m_ram[offset & 0x3fff];
86 			else
87 				data = m_romslot[(m_rom_select & 0x07) - 1]->read_rom(offset & 0x3fff);
88 		}
89 		else
90 		{
91 			if ((m_rom_select & 0x0f) == 0x08)
92 				data = m_ram[(offset & 0x3fff) | 0x4000];
93 			else
94 				data = m_rom[offset & 0x1fff];
95 
96 			/* roms selected with a read to latch */
97 			if ((offset & 0x3f00) == 0x3f00)
98 			{
99 				m_rom_latch = offset & 0x0f;
100 			}
101 		}
102 	}
103 
104 	return data;
105 }
106 
107 //-------------------------------------------------
108 //  write - cartridge data write
109 //-------------------------------------------------
110 
write(offs_t offset,uint8_t data,int infc,int infd,int romqa,int oe,int oe2)111 void electron_romp144_device::write(offs_t offset, uint8_t data, int infc, int infd, int romqa, int oe, int oe2)
112 {
113 	if (oe)
114 	{
115 		if (romqa)
116 		{
117 			if ((m_rom_select & 0x07) == 0x00)
118 				m_ram[offset & 0x3fff] = data;
119 		}
120 		else
121 		{
122 			if ((m_rom_select & 0x0f) == 0x08)
123 				m_ram[(offset & 0x3fff) | 0x4000] = data;
124 
125 			/* roms selected with a write to select */
126 			if ((offset & 0x3f00) == 0x3f00)
127 			{
128 				/* does the write match the read (upper RAM cannot be de-selected to protect *RSUBSTITUTE) */
129 				if (m_rom_latch == (offset & 0x0f) && m_rom_select != 0x08)
130 				{
131 					m_rom_select = m_rom_latch;
132 				}
133 			}
134 		}
135 	}
136 }
137 
138 
139 //**************************************************************************
140 //  IMPLEMENTATION
141 //**************************************************************************
142 
load_rom(device_image_interface & image,generic_slot_device * slot)143 image_init_result electron_romp144_device::load_rom(device_image_interface &image, generic_slot_device *slot)
144 {
145 	uint32_t size = slot->common_get_size("rom");
146 
147 	// socket accepts 8K and 16K ROM only
148 	if (size != 0x2000 && size != 0x4000)
149 	{
150 		image.seterror(IMAGE_ERROR_UNSPECIFIED, "Invalid size: Only 8K/16K is supported");
151 		return image_init_result::FAIL;
152 	}
153 
154 	slot->rom_alloc(0x4000, GENERIC_ROM8_WIDTH, ENDIANNESS_LITTLE);
155 	slot->common_load_rom(slot->get_rom_base(), size, "rom");
156 
157 	// mirror 8K ROMs
158 	uint8_t *crt = slot->get_rom_base();
159 	if (size <= 0x2000) memcpy(crt + 0x2000, crt, 0x2000);
160 
161 	return image_init_result::PASS;
162 }
163