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toggling roms.
#194665 - 06/29/09 04:30 AM
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There are two roms onboard that are toggled via 2 DIP switches ( 4 possible combinations. both may be selected, 1 selected, or both off ), the dips connect directly to the OE ( output enable ) pins to enable the specific rom outputs.
I have both ROMS loaded into the address space by default but would like the above toggle functionality in MAME. Is there a away to do this ? I'v looked through source and cannot find any examples.
Thanks...
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| Kale |
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Il Sindaco
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Reged: 09/26/03
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Posts: 155
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Loc: Naples, Italy
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Re: toggling roms.
[Re: palindrome]
#194693 - 06/29/09 03:04 PM
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From your description it looks like a normal ROM bankswitch. If so, you should see what I/O port the OE is connected and use the bankswitch system on it (maybe with external region(s) with ROMREGION_ERASEFF and a region size multiplied by 2, if that will simplify your life). For an example, check the bank instances in the sfbonus.c driver. When the ROM is enabled, you call a bankswitch with length = 0, when it's disabled, you call the bankswitch with length = size of the ROM. If done correctly, the latter case will call that region with everything filled with 0xff.
Edited by Kale (06/29/09 03:14 PM)
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