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Diffstat (limited to 'src/mame/machine/cchip.c')
-rw-r--r-- | src/mame/machine/cchip.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/src/mame/machine/cchip.c b/src/mame/machine/cchip.c new file mode 100644 index 00000000000..8424f33b711 --- /dev/null +++ b/src/mame/machine/cchip.c @@ -0,0 +1,184 @@ +/*************************************************************************** + + cchip.c + +This file contains routines to interface with the Taito Controller Chip +(or "Command Chip") version 1. It's currently used by Superman and Mega +Blast. [Further cchip emulation is in machine/rainbow.c, machine/volfied.c, +drivers/opwolf.c] + +According to Richard Bush, the C-Chip is an encrypted Z80 which communicates +with the main board as a protection feature. + + +Superman (revised SJ 060601) +-------- + +In Superman, the C-chip's main purpose is to handle player inputs and +coins and pass commands along to the sound chip. + +The 68k queries the c-chip, which passes back $100 bytes of 68k code which +are then executed in RAM. To get around this, we hack in our own code to +communicate with the sound board, since we are familiar with the interface +as it's used in Rastan and Super Space Invaders '91. + +It is believed that the NOPs in the 68k code are there to supply the +necessary cycles to the cchip to switch banks. + +This code requires that the player & coin inputs be in input ports 2-4. + + +Mega Blast +---------- + +C-Chip simply used as RAM, the game doesn't even bother to change banks. +It does read the chip id though. The dump is confirmed to be from an +original board. + +***************************************************************************/ + +#include "driver.h" +#include "includes/taito_f2.h" + +static UINT16 current_bank = 0; + +static UINT8 cc_port = 0; + +/* This code for sound communication is a hack, it will not be + identical to the code derived from the real c-chip */ + +static UINT8 superman_code[40] = +{ + 0x48, 0xe7, 0x80, 0x80, /* MOVEM.L D0/A0,-(A7) ( Preserve Regs ) */ + 0x20, 0x6d, 0x1c, 0x40, /* MOVEA.L ($1C40,A5),A0 ( Load sound pointer in A0 ) */ + 0x30, 0x2f, 0x00, 0x0c, /* MOVE.W ($0C,A7),D0 ( Fetch sound number ) */ + 0x10, 0x80, /* MOVE.B D0,(A0) ( Store it on sound pointer ) */ + 0x52, 0x88, /* ADDQ.W #1,A0 ( Increment sound pointer ) */ + 0x20, 0x3c, 0x00, 0xf0, 0x1c, 0x40, /* MOVE.L #$F01C40,D0 ( Load top of buffer in D0 ) */ + 0xb1, 0xc0, /* CMPA.L D0,A0 ( Are we there yet? ) */ + 0x66, 0x04, /* BNE.S *+$6 ( No, we arent, skip next line ) */ + 0x41, 0xed, 0x1c, 0x20, /* LEA ($1C20,A5),A0 ( Point to the start of the buffer ) */ + 0x2b, 0x48, 0x1c, 0x40, /* MOVE.L A0,($1C40,A5) ( Store new sound pointer ) */ + 0x4c, 0xdf, 0x01, 0x01, /* MOVEM.L (A7)+, D0/A0 ( Restore Regs ) */ + 0x4e, 0x75 /* RTS ( Return ) */ +}; + +MACHINE_RESET( cchip1 ) +{ + state_save_register_global(current_bank); + state_save_register_global(cc_port); +} + +/************************************* + * + * Writes to C-Chip - Important Bits + * + *************************************/ + +WRITE16_HANDLER( cchip1_ctrl_w ) +{ + /* value 2 is written here */ +} + +WRITE16_HANDLER( cchip1_bank_w ) +{ + current_bank = data & 7; +} + +WRITE16_HANDLER( cchip1_ram_w ) +{ + if (current_bank == 0 && offset == 0x03) + { + cc_port = data; + + coin_lockout_w(1, data & 0x08); + coin_lockout_w(0, data & 0x04); + coin_counter_w(1, data & 0x02); + coin_counter_w(0, data & 0x01); + } + else + { +logerror("cchip1_w pc: %06x bank %02x offset %04x: %02x\n",activecpu_get_pc(),current_bank,offset,data); + } +} + + +/************************************* + * + * Reads from C-Chip + * + *************************************/ + +READ16_HANDLER( cchip1_ctrl_r ) +{ + /* + Bit 2 = Error signal + Bit 0 = Ready signal + */ + return 0x01; /* Return 0x05 for C-Chip error */ +} + +READ16_HANDLER( cchip1_ram_r ) +{ + /* Check for input ports */ + if (current_bank == 0) + { + switch (offset) + { + case 0x00: return readinputportbytag("IN0"); /* Player 1 controls + START1 */ + case 0x01: return readinputportbytag("IN1"); /* Player 2 controls + START2 */ + case 0x02: return readinputportbytag("IN2"); /* COINn + SERVICE1 + TILT */ + case 0x03: return cc_port; + } + } + + /* Other non-standard offsets */ + + if (current_bank == 1 && offset <= 0xff) + { + if (offset < 40) /* our hack code is only 40 bytes long */ + return superman_code[offset]; + else /* so pad with zeros */ + return 0; + } + + if (current_bank == 2) + { + switch (offset) + { + case 0x000: return 0x47; + case 0x001: return 0x57; + case 0x002: return 0x4b; + } + } + +logerror("cchip1_r bank: %02x offset: %04x\n",current_bank,offset); + return 0; +} + + +/* Mega Blast */ + +UINT16 *cchip2_ram; + +WRITE16_HANDLER( cchip2_word_w ) +{ + logerror("cchip2_w pc: %06x offset %04x: %02x\n", activecpu_get_pc(), offset, data); + + COMBINE_DATA(&cchip2_ram[offset]); +} + +READ16_HANDLER( cchip2_word_r ) +{ + /* C-Chip ID */ + + if (offset == 0x401) + { + return 0x01; + } + + logerror("cchip2_r offset: %04x\n", offset); + + return cchip2_ram[offset]; +} + |