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[Core/MD] added emulation of 68k delay during Z80 acccess to 68k bus (fixes graphical glitch on Rick Dangerous II title screen introduced after adding emulation of 68k bus refresh delays)

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ekeeke 2024-05-01 18:44:46 +02:00
parent 0c45a8a8ab
commit f9f16d7a55
5 changed files with 9 additions and 3 deletions
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3
HISTORY.txt
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@ -76,7 +76,8 @@ Genesis Plus GX 1.7.5 (xx/xx/xxxx) (Eke-Eke)
* added support for Everdrive extended SSF mapper * added support for Everdrive extended SSF mapper
* added support for MegaSD CD hardware overlay (MD+ hacks) and extended SSF2 / ROM write mappers * added support for MegaSD CD hardware overlay (MD+ hacks) and extended SSF2 / ROM write mappers
* added emulation of Z80 halt when accessing 68k bus during DMA from 68k bus * added emulation of Z80 halt when accessing 68k bus during DMA from 68k bus
* added basic emulation of 68k bus access refresh delays (fixes Super Airwolf graphical glitch during intro & some Krikzz's mcd-verificator timing tests) * added emulation of 68k delay during Z80 acccess to 68k bus
* added (basic) emulation of 68k bus refresh delays (fixes Super Airwolf graphical glitch during intro & some Krikzz's mcd-verificator timing tests)
* added (very basic) emulation of Flashkit MD hardware * added (very basic) emulation of Flashkit MD hardware
* added emulation of Micro Machines USA on-board TMSS bypass logic hardware * added emulation of Micro Machines USA on-board TMSS bypass logic hardware
* added SRAM support for games larger than 8MB * added SRAM support for games larger than 8MB

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9
core/memz80.c
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@ -108,8 +108,13 @@ static void z80_request_68k_bus_access(void)
} }
} }
/* average Z80 wait-states when accessing 68k area */ /* approximate 68k wait-states during Z80 access to 68k bus (cf https://docs.google.com/document/d/1ST9GbFfPnIjLT5loytFCm3pB0kWQ1Oe34DCBBV8saY8) */
Z80.cycles += 3 * 15; /* value is adjusted to get ride of graphical glitches in Rick Dangerous 2 title screen when bus refresh delays are also emulated and still get */
/* "M68K DELAY ON Z80 ROM READ" test "passed" in Ti_'s test ROM (misc_test.bin), although the measured delay value is still slightly too high. */
m68k.cycles += ((Z80.cycles % 7) + 68);
/* average Z80 wait-states when accessing 68k bus (cf https://docs.google.com/document/d/1ST9GbFfPnIjLT5loytFCm3pB0kWQ1Oe34DCBBV8saY8) */
Z80.cycles += (3 * 15);
} }
unsigned char z80_memory_r(unsigned int address) unsigned char z80_memory_r(unsigned int address)