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[Core/MD] added emulation of "Micro Machines USA" on-board TMSS bypass logic hardware (fixes lockout when TMSS Boot ROM is enabled)

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ekeeke 2021-02-23 14:59:59 +01:00
parent bb8f3b3113
commit bc8d1ae2b2
6 changed files with 32 additions and 2 deletions
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1
HISTORY.txt
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@ -55,6 +55,7 @@ Genesis Plus GX 1.7.5 (xx/xx/xxxx) (Eke-Eke)
* added support for some new unlicensed games with copy protection (Thunderbolt II, Tom Clown, Chaoji Puke / Super Poker, Rock Heaven, Rock World)
* added support for Everdrive extended SSF mapper
* added (very basic) emulation of Flashkit MD hardware
* added emulation of Micro Machines USA on-board TMSS bypass logic hardware
* improved console region auto-detection for a few PAL-only games (The Smurfs Travel the World & Williams Arcade's Greatest Hits)
* improved I2C EEPROM boards emulation accuracy
* improved SVP memory handlers accuracy (fixes Virtua Racing debug mode)

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builds/genesis_plus_gx_libretro.dll
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builds/genplus_cube.dol
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31
core/cart_hw/md_cart.c
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@ -2,7 +2,7 @@
* Genesis Plus
* Mega Drive cartridge hardware support
*
* Copyright (C) 2007-2020 Eke-Eke (Genesis Plus GX)
* Copyright (C) 2007-2021 Eke-Eke (Genesis Plus GX)
*
* Many cartridge protections were initially documented by Haze
* (http://haze.mameworld.info/)
@ -79,6 +79,7 @@ static void mapper_256k_multi_w(uint32 address, uint32 data);
static void mapper_wd1601_w(uint32 address, uint32 data);
static uint32 mapper_64k_radica_r(uint32 address);
static uint32 mapper_128k_radica_r(uint32 address);
static void mapper_sr16v1_w(uint32 address, uint32 data);
static void default_time_w(uint32 address, uint32 data);
static void default_regs_w(uint32 address, uint32 data);
static uint32 default_regs_r(uint32 address);
@ -737,6 +738,11 @@ void md_cart_init(void)
zbank_memory_map[i].write = mapper_smw_64_w;
}
}
else if ((*(uint16 *)(cart.rom + 0x04) == 0x0000) && (*(uint16 *)(cart.rom + 0x06) == 0x0104) && (rominfo.checksum == 0x31fc))
{
/* Micro Machines (USA) custom TMSS bypass logic */
m68k.memory_map[0xa1].write8 = mapper_sr16v1_w;
}
else if (cart.romsize > 0x400000)
{
/* assume linear ROM mapping by default (max. 10MB) */
@ -1897,6 +1903,29 @@ static uint32 mapper_128k_radica_r(uint32 address)
return 0xffff;
}
/*
Custom logic (ST 16S25HB1 PAL) used in Micro Machines US cartridge (SR16V1.1 board)
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
/VRES is asserted after write access to 0xA14101 (TMSS bank-shift register)
with D0=1 (cartridge ROM access enabled instead of TMSS Boot ROM) being detected
*/
static void mapper_sr16v1_w(uint32 address, uint32 data)
{
/* 0xA10000-0xA1FFFF address range is mapped to I/O and Control registers */
ctrl_io_write_byte(address, data);
/* cartridge uses /LWR, /AS and VA1-VA18 (only VA8-VA17 required to decode access to TMSS bank-shift register) */
if ((address & 0xff01) == 0x4101)
{
/* cartridge ROM is enabled when D0=1 */
if (data & 0x01)
{
gen_reset(0);
}
}
}
/************************************************************
default !TIME signal handler
*************************************************************/

2
core/cart_hw/md_cart.h
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@ -2,7 +2,7 @@
* Genesis Plus
* Mega Drive cartridge hardware support
*
* Copyright (C) 2007-2020 Eke-Eke (Genesis Plus GX)
* Copyright (C) 2007-2021 Eke-Eke (Genesis Plus GX)
*
* Most cartridge protections were initially documented by Haze
* (http://haze.mameworld.info/)