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Me Tarzan, you Jane....

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RobertoFresca 2016-05-28 13:09:29 -03:00
parent 958731ef5a
commit cc87a10563
1 changed files with 7 additions and 7 deletions
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src/mame/drivers/magicfly.cpp
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@ -253,23 +253,23 @@
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After check the last bit of $1800, code jump into a loop ($DA30)... After check the last bit of $1800, the code jumps into a loop ($DA30)...
BEHAVIOUR OF BOOT CHECK (magicfly): BEHAVIOUR OF BOOT CHECK (magicfly):
1) Fill the video RAM with spaces (0x20), and color RAM with 0x15. 1) Fills the video RAM with spaces (0x20), and color RAM with 0x15.
2) Check bit 7 of $1800 (video RAM, 1st offset) if activated. 2) Checks bit 7 of $1800 (video RAM, 1st offset) if it's active.
3) If true, go to $DA30 (incremented fill infinite loop). 3) If true, go to $DA30 (incremented fill infinite loop).
4) If not, fill the video RAM with spaces (0x20), and color RAM with 0x1F. 4) If not, fills the video RAM with spaces (0x20), and color RAM with 0x1F.
5) Check bit 7 of $1800 (video RAM, 1st offset) if activated. 5) Checks bit 7 of $1800 (video RAM, 1st offset) if it's active.
6) If not, go to $DA30 (incremented fill infinite loop). 6) If not, go to $DA30 (incremented fill infinite loop).
7) If true, returns and continue to NORMAL GAME. 7) If true, returns and continues to NORMAL GAME.
Since bits 0-2 are for regular colors, seems that bit 3 in color RAM Since bits 0-2 are for regular colors, seems that bit 3 in color RAM
(bit 2 for 7mezzo) is mirrored to bit 7 through a kind of device. (bit 2 for 7mezzo) is mirrored to bit 7 through a kind of device.
This is the only explanation I found to allow a normal boot, and seems to be This is the only explanation I found to allow a normal boot, and seems to be
created as a protection method that don't allow owners to use a ROM-swap on created as a protection method that doesn't allow owners to do a ROM-swap on
their boards, converting from one game to another. their boards, converting from one game to another.