1 /***************************************************************************
2
3 cchip.c
4
5 This file contains routines to interface with the Taito Controller Chip
6 (or "Command Chip") version 1. It's currently used by Superman and Mega
7 Blast. [Further cchip emulation is in machine/rainbow.c, machine/volfied.c,
8 drivers/opwolf.c]
9
10 According to Richard Bush, the C-Chip is an encrypted Z80 which communicates
11 with the main board as a protection feature.
12
13
14 Superman (revised SJ 060601)
15 --------
16
17 In Superman, the C-chip's main purpose is to handle player inputs and
18 coins and pass commands along to the sound chip.
19
20 The 68k queries the c-chip, which passes back $100 bytes of 68k code which
21 are then executed in RAM. To get around this, we hack in our own code to
22 communicate with the sound board, since we are familiar with the interface
23 as it's used in Rastan and Super Space Invaders '91.
24
25 It is believed that the NOPs in the 68k code are there to supply the
26 necessary cycles to the cchip to switch banks.
27
28 This code requires that the player & coin inputs be in input ports 4-6.
29
30
31 Mega Blast
32 ----------
33
34 C-Chip simply used as RAM, the game doesn't even bother to change banks.
35 It does read the chip id though. The dump is confirmed to be from an
36 original board.
37
38 ***************************************************************************/
39
40 #include "driver.h"
41 #include "state.h"
42
43 static int current_bank = 0;
44
45 static UINT8 cc_port = 0;
46
47 /* This code for sound communication is a hack, it will not be
48 identical to the code derived from the real c-chip */
49
50 static UINT8 superman_code[40] =
51 {
52 0x48, 0xe7, 0x80, 0x80, /* MOVEM.L D0/A0,-(A7) ( Preserve Regs ) */
53 0x20, 0x6d, 0x1c, 0x40, /* MOVEA.L ($1C40,A5),A0 ( Load sound pointer in A0 ) */
54 0x30, 0x2f, 0x00, 0x0c, /* MOVE.W ($0C,A7),D0 ( Fetch sound number ) */
55 0x10, 0x80, /* MOVE.B D0,(A0) ( Store it on sound pointer ) */
56 0x52, 0x88, /* ADDQ.W #1,A0 ( Increment sound pointer ) */
57 0x20, 0x3c, 0x00, 0xf0, 0x1c, 0x40, /* MOVE.L #$F01C40,D0 ( Load top of buffer in D0 ) */
58 0xb1, 0xc0, /* CMPA.L D0,A0 ( Are we there yet? ) */
59 0x66, 0x04, /* BNE.S *+$6 ( No, we arent, skip next line ) */
60 0x41, 0xed, 0x1c, 0x20, /* LEA ($1C20,A5),A0 ( Point to the start of the buffer ) */
61 0x2b, 0x48, 0x1c, 0x40, /* MOVE.L A0,($1C40,A5) ( Store new sound pointer ) */
62 0x4c, 0xdf, 0x01, 0x01, /* MOVEM.L (A7)+, D0/A0 ( Restore Regs ) */
63 0x4e, 0x75 /* RTS ( Return ) */
64 };
65
MACHINE_INIT(cchip1)66 MACHINE_INIT( cchip1 )
67 {
68 state_save_register_int ("cchip1", 0, "current_bank", ¤t_bank);
69 state_save_register_UINT8("cchip1", 0, "cc_port", &cc_port, 1);
70 }
71
WRITE16_HANDLER(cchip1_word_w)72 WRITE16_HANDLER( cchip1_word_w )
73 {
74 if (offset == 0x600)
75 {
76 current_bank = data;
77 }
78 else if (current_bank == 0 && offset == 0x003)
79 {
80 cc_port = data;
81
82 coin_lockout_w(1, data & 0x08);
83 coin_lockout_w(0, data & 0x04);
84 coin_counter_w(1, data & 0x02);
85 coin_counter_w(0, data & 0x01);
86 }
87 else
88 {
89 logerror("cchip1_w pc: %06x bank %02x offset %04x: %02x\n",activecpu_get_pc(),current_bank,offset,data);
90 }
91 }
92
READ16_HANDLER(cchip1_word_r)93 READ16_HANDLER( cchip1_word_r )
94 {
95 /* C-Chip ID */
96
97 if (offset == 0x401)
98 {
99 return 0x01;
100 }
101
102 /* Check for input ports */
103
104 if (current_bank == 0)
105 {
106 switch (offset)
107 {
108 case 0x000: return readinputport(4);
109 case 0x001: return readinputport(5);
110 case 0x002: return readinputport(6);
111 case 0x003: return cc_port;
112 }
113 }
114
115 /* Other non-standard offsets */
116
117 if (current_bank == 1 && offset <= 0xff)
118 {
119 if (offset < 40) /* our hack code is only 40 bytes long */
120 return superman_code[offset];
121 else /* so pad with zeros */
122 return 0;
123 }
124
125 if (current_bank == 2)
126 {
127 switch (offset)
128 {
129 case 0x000: return 0x47;
130 case 0x001: return 0x57;
131 case 0x002: return 0x4b;
132 }
133 }
134
135 logerror("cchip1_r bank: %02x offset: %04x\n",current_bank,offset);
136 return 0;
137 }
138
139
140 /* Mega Blast */
141
142 data16_t *cchip_ram;
143
WRITE16_HANDLER(cchip2_word_w)144 WRITE16_HANDLER( cchip2_word_w )
145 {
146 logerror("cchip2_w pc: %06x offset %04x: %02x\n", activecpu_get_pc(), offset, data);
147
148 COMBINE_DATA(&cchip_ram[offset]);
149 }
150
READ16_HANDLER(cchip2_word_r)151 READ16_HANDLER( cchip2_word_r )
152 {
153 /* C-Chip ID */
154
155 if (offset == 0x401)
156 {
157 return 0x01;
158 }
159
160 logerror("cchip2_r offset: %04x\n", offset);
161
162 return cchip_ram[offset];
163 }
164
165