NES 2.0 Mapper 328: Difference between revisions
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(more information about this oddball) |
(→Random number generator or Protection ($CE80-$CEFF, $FE80-$FEFF, read): it's copy protection, we don't need to muse on that. also i disassembled the relevant program.) |
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==Random number generator or Protection ($CE80-$CEFF, $FE80-$FEFF, read)== | ==Random number generator or Protection ($CE80-$CEFF, $FE80-$FEFF, read)== | ||
Mask: unknown. If what CaH4e3 wrote (quoted below) is accurate, $ | Mask: unknown. If what CaH4e3 wrote (quoted below) is accurate, $BFFF. | ||
D~7654 3210 | D~7654 3210 | ||
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++-+- Random bits | ++-+- Random bits | ||
CaH4e3 wrote that the "PRG EPROM has copy protected areas with "weak bits", which is tested at some points of the program. [The random numbers are t]rying to simulate "weak bits" behaviour" | |||
The relevant program calculates a 16-bit checksum of the memory in each of these regions and loops until the checksum ''changes''. | |||
Latest revision as of 19:44, 27 September 2018
NES 2.0 mapper 328 is used for the Test Ver. 1.01 Dlya Proverki TV Pristavok test cartridge. Its UNIF board name is UNL-RT-01. There is only 16K of PRG and 2K of CHR and mirroring is hard-wired.
Random number generator or Protection ($CE80-$CEFF, $FE80-$FEFF, read)
Mask: unknown. If what CaH4e3 wrote (quoted below) is accurate, $BFFF.
D~7654 3210
---------
1111 RR1R
++-+- Random bits
CaH4e3 wrote that the "PRG EPROM has copy protected areas with "weak bits", which is tested at some points of the program. [The random numbers are t]rying to simulate "weak bits" behaviour"
The relevant program calculates a 16-bit checksum of the memory in each of these regions and loops until the checksum changes.
