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Sega System 1's "SW 0 READ FROM" dip switch
#291138 - 07/07/12 01:43 PM
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I hope this is the right place to ask this, if not then just move or delete it.
What's the purpose of the "SW 0 READ FROM" dip switch (switch 8 on bank B)? I've been fiddling with it and can't see any obvious differences.
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Re: Sega System 1's "SW 0 READ FROM" dip switch
[Re: SanRinSanChan]
#291180 - 07/08/12 02:55 AM
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> What's the purpose of the "SW 0 READ FROM" dip switch (switch 8 on bank B)? I've been fiddling with it and can't see any obvious differences.
There is NO difference in MAME because BOTH IO adresses (0x0d AND 0x10) are mapped to read Dip Switch bank B :
Code:
AM_RANGE(0x0d, 0x0d) AM_MIRROR(0x02) AM_READ_PORT("SWB") /* DIP1 some games read it from here... */
AM_RANGE(0x10, 0x10) AM_MIRROR(0x03) AM_READ_PORT("SWB") /* DIP1 ... and some others from here but there are games which check BOTH! */
 Steph from The Ultimate Patchers 
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Re: Sega System 1's "SW 0 READ FROM" dip switch
[Re: stephh]
#291192 - 07/08/12 09:33 AM
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> > What's the purpose of the "SW 0 READ FROM" dip switch (switch 8 on bank B)? I've
> been fiddling with it and can't see any obvious differences.
>
> There is NO difference in MAME because BOTH IO adresses (0x0d AND 0x10) are mapped to
> read Dip Switch bank B :
>
> AM_RANGE(0x0d, 0x0d) AM_MIRROR(0x02) AM_READ_PORT("SWB") /* DIP1 some games read it
> from here... */
> AM_RANGE(0x10, 0x10) AM_MIRROR(0x03) AM_READ_PORT("SWB") /* DIP1 ... and some others
> from here but there are games which check BOTH! */
>
>
> Steph from The Ultimate Patchers
Ok, that's interesting, because on my Spatter PCB changing the eighth dip switch changes the backgrounds. In MAME always the same two backgrounds are shown during the gameplay demos in the attract mode. On mine changing the switch changes the backgrounds. I'll have to check it out further.
Thanks!
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I haven't been able to work out exactly what's happening. My Spatter ROMs are not in MAME and have higher numbers so it may be a later revision. It's different in any case, because it definitely has the ability to change backgrounds.
I've found a few more games where I have unemulated versions, the US version of Monster Maulers, a UK version of Pleiads, a newer version of Iron Horse, a new version of Escape from the Planet of the Robot Monsters, a version of SDI I'm not sure about, a conversion from After Burner to After Burner II and a few more I have to check out.
[ATTACHED IMAGE]
Edited by SanRinSanChan (08/03/12 10:15 AM)
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Re: Sega System 1's "SW 0 READ FROM" dip switch
[Re: SanRinSanChan]
#293256 - 08/03/12 11:47 PM
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Only one way to find out, try your romset in MAME. Though if I had to guess, I think there's more chance it's a small MAME bug somewhere and not due to ROM revision.
Bonus question: got time/willingness to dump and include your unemulated games to MAME?
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