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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
02738 Documentation Minor N/A Dec 12, 2008, 23:50 Dec 27, 2008, 02:50
Tester Smitdogg View Status Public Platform
Assigned To aaron Resolution Fixed OS
Status [?] Resolved Driver
Version 0.128u5 Fixed in Version 0.129 Build
Fixed in Git Commit Github Pull Request #
Summary 02738: zoar: The rom marked as bad dump is not bad.
Description The rom marked as bad dump is not bad. I have the pcb and I dumped that rom many times and I get the same crc every time.
Steps To Reproduce
Additional Information
Github Commit
Flags Verified with Original
Regression Version
Affected Sets / Systems zoar
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Notes
7
User avatar
No.03291
Tafoid
Administrator
Dec 13, 2008, 00:16
From Source:
/* At location 0xD50A is what looks like an undocumented opcode. I tried
       implementing it given what opcode 0x23 should do, but it still didn't
       work in demo mode. So this could be another protection or a bad ROM read.
       I'm NOPing it out for now. */

Given your board isn't the original board used for the set and the roms are the same for that main cpu rom that has been around a long time and the repeated attempts - I'd lean on it being a opcode issue rather than a BAD_DUMP issue.
User avatar
No.03296
Haze
Senior Tester
Dec 13, 2008, 11:58
yeah, probably.. there are similar issues with treasure island too. It might be a subtle extra to the protection / encryption..

does this board (if it's an original you have) use one of those big data east CPU blocks too?
User avatar
No.03300
Smitdogg
Senior Tester
Dec 13, 2008, 16:23
Yeah, it's on there, says CPU-7 on it. I'm sending pics to Guru later and I will eventually get the pals dumped and I'm trying to get a rig set up where I can make pcb videos, so I'll have more info later.
User avatar
No.03301
Kale
Developer
Dec 13, 2008, 20:45
edited on: Dec 13, 2008, 20:47
Auto-citation (Treasure Island):
"At location 0xa2b6 there's a strange RLA followed by a BPL that reads from an
    unmapped area that causes the game to fail in several circumstances.On the Cassette
    version the RLA (33) is in reality a BIT (24),so I'm guessing that there's something
    wrong going on in the encryption scheme."

For sure it's not a ROM issue (unlikely it's a bitrot),more likely to be an encryption issue. Probably the DECO-7 can do more than just shifting the opcodes bits on write types,and it's likely that it should be properly converted & handled to a cpu-sub-type of M6502 instead of just change the opcodes at run time...
User avatar
No.03310
Smitdogg
Senior Tester
Dec 15, 2008, 20:22
I'm sending the board to Guru so he can "attack the epoxy block" and take measurements etc.
User avatar
No.03314
Haze
Senior Tester
Dec 15, 2008, 22:10
makes sense I guess, although I think there are bootlegs which reproduce the Burger Time encryption with simply logic (although this might be something more, and I guess it would be interesting to see exactly which CPU is inside the block, as it could be relying on custom behavior of the chips produced by a certain manufacturer..)
User avatar
No.03409
aaron
Developer
Dec 27, 2008, 02:50
Fixed the ROM definition. Other issues are still present, obviously.