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DU Update: Final Lap 3
#234929 - 09/28/10 08:03 PM
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| Fever |
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Reformed Sk3n3 Quitter
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Reged: 09/21/03
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Posts: 2090
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Loc: Britland
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Re: DU Update: Final Lap 3
[Re: Smitdogg]
#234945 - 09/28/10 09:38 PM
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Re: DU Update: Final Lap 3
[Re: Fever]
#234947 - 09/28/10 09:45 PM
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It's just a joke. Go to bed.
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Re: DU Update: Final Lap 3
[Re: Smitdogg]
#234956 - 09/29/10 01:48 AM
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Does having this board let us re-dump the "sys2c65c.bin" that is marked as BAD_DUMP? Or is there a MCU that needs to be decapped for that to happen?
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Re: DU Update: Final Lap 3
[Re: jonwil]
#234958 - 09/29/10 02:00 AM
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That situation is kind of interesting, I've been discovering stuff about it today, other people probably already knew... It's actually SYS2-C68 on this board and the dump matches the rom named that way in some Super World Stadium sets. I'm not sure if all Final Lap 3 sets use this one or if some of them used the SYS2C65C one or what, but it's definitely correct on this set for it to use the C68 one. I've powered up the board and it runs perfectly. The chip isn't anything special, any programmer can read it, I think it might have just been skipped over during some dumps because it's labeled funky? I don't know. This chip isn't an MCU, it looks like it's data for the MCU.
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Re: DU Update: Final Lap 3
[Re: Smitdogg]
#234962 - 09/29/10 03:00 AM
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> That situation is kind of interesting, I've been discovering stuff about it today,
> other people probably already knew... It's actually SYS2-C68 on this board and the
> dump matches the rom named that way in some Super World Stadium sets. I'm not sure if
> all Final Lap 3 sets use this one or if some of them used the SYS2C65C one or what,
> but it's definitely correct on this set for it to use the C68 one. I've powered up
> the board and it runs perfectly. The chip isn't anything special, any programmer can
> read it, I think it might have just been skipped over during some dumps because it's
> labeled funky? I don't know. This chip isn't an MCU, it looks like it's data for the
> MCU.
I'm trying to make sense of this MCU malarky. It's a bit confusing.
Most System 2 games use a 6805-based MCU with an internal ROM (the Namco C65). Not all games have the SYS2C65C etc. external ROM.
Later games use an M37450 MCU (which we don't currently support). There appear to be two variants - the Namco C68 with internal ROM and a ROM-less off-the-shelf Mitsubishi part which requires an external ROM.
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Re: DU Update: Final Lap 3
[Re: Phil Bennett]
#235000 - 09/29/10 03:52 PM
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Do we have a dump of the Namco C68 MCU? Or do we need to send one off for decapping?
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Re: DU Update: Final Lap 3
[Re: jonwil]
#235049 - 09/29/10 09:47 PM
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> Do we have a dump of the Namco C68 MCU? Or do we need to send one off for decapping?
No but there is one in the decapping queue. If I remember, Charles attempted to trojan the ROM but drew a blank.
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| R. Belmont |
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Cuckoo for IGAvania
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Re: DU Update: Final Lap 3
[Re: Phil Bennett]
#235054 - 09/29/10 10:54 PM
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> Later games use an M37450 MCU (which we don't currently support). There appear to be
> two variants - the Namco C68 with internal ROM and a ROM-less off-the-shelf
> Mitsubishi part which requires an external ROM.
I'll be doing an M50740/50741 core in the near future, which has the same instruction set as the 37450...
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Re: DU Update: Final Lap 3
[Re: Phil Bennett]
#235060 - 09/30/10 12:15 AM
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Phil, you are absolutely correct about the MCU differences. The early hardware used a 68705, and later games (mostly 3D ones with analog controls) used the M37450 which is a 6502 variant with more instructions.
The C68 MCU has a pin to select internal or external ROM that is brought out to a jumper on the motherboard. The pin is latched internally during a reset pulse so subsequent changes are ignored. Just to be sure I verified with a trojan that the pin state really is ignored after a reset.
I also tried various out-of-spec reset pulses, and changing the external memory map in hopes that it might crash. No such luck.
Some games like Suzuka 8 Hours will use the C68's internal ROM and have no external ROM. Others like Final Lap 3use the external ROM exclusively. I feel certain the internal ROM contents are the same for all boards that use the chip.
I sent a C68 to Guru for decapping, it's definitely on the list.
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| R. Belmont |
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Cuckoo for IGAvania
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> The C68 MCU has a pin to select internal or external ROM that is brought out to a
> jumper on the motherboard. The pin is latched internally during a reset pulse so
> subsequent changes are ignored. Just to be sure I verified with a trojan that the pin
> state really is ignored after a reset.
Couldn't you cut the trace and hardwire it to be pulled up or down, whichever selects "external ROM"?
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Re: DU Update: Final Lap 3
[Re: R. Belmont]
#235183 - 10/01/10 01:15 AM
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I am assuming that if you did that, the internal ROM would be locked out and inaccessible.
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