1 // license:BSD-3-Clause
2 // copyright-holders:Curt Coder
3 /**********************************************************************
4
5 Brown Boxes Double Quick Brown Box emulation
6
7 **********************************************************************/
8
9 /*
10
11 TODO:
12
13 - 64/128 mode switch
14 - dump of the initial NVRAM contents
15
16 */
17
18 #include "emu.h"
19 #include "dqbb.h"
20
21
22
23 //**************************************************************************
24 // DEVICE DEFINITIONS
25 //**************************************************************************
26
27 DEFINE_DEVICE_TYPE(C64_DQBB, c64_dqbb_cartridge_device, "c64_dqbb", "C64 Double Quick Brown Box cartridge")
28
29
30
31 //**************************************************************************
32 // LIVE DEVICE
33 //**************************************************************************
34
35 //-------------------------------------------------
36 // c64_dqbb_cartridge_device - constructor
37 //-------------------------------------------------
38
c64_dqbb_cartridge_device(const machine_config & mconfig,const char * tag,device_t * owner,uint32_t clock)39 c64_dqbb_cartridge_device::c64_dqbb_cartridge_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
40 device_t(mconfig, C64_DQBB, tag, owner, clock),
41 device_c64_expansion_card_interface(mconfig, *this),
42 device_nvram_interface(mconfig, *this),
43 m_cs(0),
44 m_we(0)
45 {
46 }
47
48
49 //-------------------------------------------------
50 // device_start - device-specific startup
51 //-------------------------------------------------
52
device_start()53 void c64_dqbb_cartridge_device::device_start()
54 {
55 // allocate memory
56 m_nvram.allocate(0x4000);
57
58 // state saving
59 save_item(NAME(m_cs));
60 save_item(NAME(m_we));
61 }
62
63
64 //-------------------------------------------------
65 // device_reset - device-specific reset
66 //-------------------------------------------------
67
device_reset()68 void c64_dqbb_cartridge_device::device_reset()
69 {
70 m_exrom = 0; // TODO 1 in 128 mode
71 m_game = 1;
72 m_cs = 0;
73 m_we = 0;
74 }
75
76
77 //-------------------------------------------------
78 // c64_cd_r - cartridge data read
79 //-------------------------------------------------
80
c64_cd_r(offs_t offset,uint8_t data,int sphi2,int ba,int roml,int romh,int io1,int io2)81 uint8_t c64_dqbb_cartridge_device::c64_cd_r(offs_t offset, uint8_t data, int sphi2, int ba, int roml, int romh, int io1, int io2)
82 {
83 if (!m_cs && (!roml || !romh))
84 {
85 data = m_nvram[offset & 0x3fff];
86 }
87
88 return data;
89 }
90
91
92 //-------------------------------------------------
93 // c64_cd_w - cartridge data write
94 //-------------------------------------------------
95
c64_cd_w(offs_t offset,uint8_t data,int sphi2,int ba,int roml,int romh,int io1,int io2)96 void c64_dqbb_cartridge_device::c64_cd_w(offs_t offset, uint8_t data, int sphi2, int ba, int roml, int romh, int io1, int io2)
97 {
98 if (!m_cs && m_we && (offset >= 0x8000 && offset < 0xc000))
99 {
100 m_nvram[offset & 0x3fff] = data;
101 }
102 else if (!io1)
103 {
104 /*
105
106 bit description
107
108 0
109 1
110 2 GAME
111 3
112 4 WE
113 5
114 6 EXROM
115 7 _CS
116
117 */
118
119 m_exrom = !BIT(data, 6);
120 m_game = !BIT(data, 2);
121 m_we = BIT(data, 4);
122 m_cs = BIT(data, 7);
123 }
124 }
125