trunk/src/mess/machine/md_rom.c
| r21458 | r21459 | |
|---|
| 1072 | 1072 | /*------------------------------------------------- |
| 1073 | 1073 | BEGGAR PRINCE |
| 1074 | 1074 | This game uses cart which is the same as SEGA_SRAM |
| 1075 | | + bankswitch mechanism to remap some 256K chunk of |
| 1076 | | ROM and to enable/disable SRAM (not yet fully |
| 1077 | | emulated) |
| 1075 | + bankswitch mechanism for first 256KB of the image: |
| 1076 | depending on bit7 of the value written at 0xe00/2, |
| 1077 | accesses to 0x00000-0x3ffff go to the first 256KB |
| 1078 | of ROM, or to the second to last 256KB chunk (usually |
| 1079 | mapped to 0x380000-0x3bffff). SRAM is mapped at |
| 1080 | the end of ROM. |
| 1078 | 1081 | -------------------------------------------------*/ |
| 1079 | 1082 | |
| 1080 | 1083 | READ16_MEMBER(md_rom_beggarp_device::read) |
| 1081 | 1084 | { |
| 1082 | | if (m_mode & 2) |
| 1083 | | { |
| 1084 | | //000000-03ffff = ROM bank 15 x 256k |
| 1085 | | //040000-3bffff = ROM banks 2 to 15 x256k |
| 1086 | | //3c0000-3fffff = ?? SRAM ?? (32k?) |
| 1087 | | if (offset < 0x040000/2) |
| 1088 | | return m_rom[offset + 0x380000/2]; |
| 1089 | | else if (offset >= m_nvram_start/2 && offset <= m_nvram_end/2 && m_nvram_active) |
| 1090 | | return m_nvram[offset & 0x3fff]; |
| 1091 | | else if (offset < 0x400000/2) |
| 1092 | | return m_rom[offset & 0x1fffff]; |
| 1093 | | } |
| 1094 | | else |
| 1095 | | { |
| 1096 | | // currently not supported |
| 1097 | | // if (m_mode & 1) //00-40 = unmapped (open bus?) |
| 1098 | | |
| 1099 | | //00-40 = ROM banks 1 to 16 x256k |
| 1100 | | if (offset < 0x400000/2) |
| 1101 | | return m_rom[offset & 0x1fffff]; |
| 1102 | | } |
| 1085 | if (offset >= m_nvram_start/2 && offset <= m_nvram_end/2 && m_nvram_active) |
| 1086 | return m_nvram[offset & 0x3fff]; |
| 1087 | |
| 1088 | if (offset < 0x040000/2) |
| 1089 | return m_mode ? m_rom[offset + 0x380000/2] : m_rom[offset]; |
| 1090 | else if (offset < 0x400000/2) |
| 1091 | return m_rom[offset & 0x1fffff]; |
| 1103 | 1092 | |
| 1104 | 1093 | return 0xffff; |
| 1105 | 1094 | } |
| 1106 | 1095 | |
| 1107 | 1096 | WRITE16_MEMBER(md_rom_beggarp_device::write) |
| 1108 | 1097 | { |
| 1109 | | if (offset >= 0x0e00/2 && offset < 0x0f00/2) // it actually writes to 0xe00/2 |
| 1110 | | { |
| 1111 | | if (!m_lock) |
| 1112 | | m_mode = (data & 0xc0) >> 6; |
| 1113 | | |
| 1114 | | m_lock = BIT(data, 5); // lock bankswitch hardware when set, until hard reset |
| 1115 | | } |
| 1116 | | |
| 1117 | | // SRAM is only accessible in mode 2 |
| 1118 | | if (offset >= m_nvram_start/2 && offset <= m_nvram_end/2 && m_nvram_active && !m_nvram_readonly && m_mode == 2) |
| 1098 | if (offset >= 0x0e00/2 && offset < 0x0f00/2) |
| 1099 | m_mode = BIT(data, 7); |
| 1100 | |
| 1101 | if (offset >= m_nvram_start/2 && offset <= m_nvram_end/2 && m_nvram_active && !m_nvram_readonly) |
| 1119 | 1102 | m_nvram[offset & 0x3fff] = data; |
| 1120 | 1103 | } |
| 1121 | 1104 | |
| r21458 | r21459 | |
|---|
| 1137 | 1120 | /*------------------------------------------------- |
| 1138 | 1121 | LEGEND OF WUKONG |
| 1139 | 1122 | This game uses cart which is the same as SEGA_SRAM |
| 1140 | | + bankswitch mechanism for last 128k of the image: |
| 1123 | + bankswitch mechanism for last 128KB of the image: |
| 1141 | 1124 | first 2MB of ROM is loaded in 0-0x200000 and |
| 1142 | 1125 | mirrored in 0x200000-0x400000, but depending on |
| 1143 | 1126 | bit7 of the value written at 0xe00/2 accesses to |