#Nes xevious rom code

The Miscellaneous ROM Area, if present, follows the CHR-ROM area and occupies the remainder of the file. If the CHR-ROM size is 16 KiB, the both units use the same bank-switched 16 KiB CHR-ROM data. Dual System ROM images, if the CHR-ROM size is 32 KiB, the first 16 KiB belong to the first unit, and the second 16 KiB of CHR-ROM belong to the second unit. If the CHR-ROM data has an odd size that cannotД«e represented by either notation, the data must be padded to a size that can be represented.ДЇor Vs. The exponent-multiplier form may only be used if the CHR-ROM size cannot be specified correctly using the simpler notation. The actual CHR-ROM size therefore becomes 2^E * (MM*2+1). If the MSB nibble is $0-E, LSB and MSB together simply specify the CHR-ROM size in 8 KiB units: Header byte 5 (LSB) and bits 4-7 of Header byte 9 (MSB) The CHR-ROM Area, if present, follows the Trainer and PRG-ROM Areas and precedes the Miscellaneous ROM Area.

The second unit only executes a dummy program that does nothing except set a flag in the shared WRAM at $6000-$67FF.

Second 8 KiB represent the second unit's PRG-ROM at CPU $E000-$FFFF.

First 32 KiB represent the first unit's PRG-ROM at CPU $8000-$FFFF.

Second 8 KiB represent the CPU $8000-$9FFF area with $4016 D2=1.

First 32 KiB represent the entire CPU $8000-$FFFF area, including the CPU $8000-$9FFF area with $4016 D2=0.

System ROM images with a total of 40 KiB PRG-ROM, which are defined to represent 32 KiB +8 KiB instead: Dual System.ДЄn exception is granted for two oddly-sized Vs. Dual System ROM images, the first half block of the specified PRG-ROM size belongs to the first unit, and the second half block of PRG-ROM belongs to the the second unit.Дў4 KiB (half-)blocks are mapped to $A000-$FFFF both in Vs. If the PRG-ROM data has an odd size that cannotД«e represented in either notation, the data must be padded to a size that can be represented. The exponent-multiplier form may only be used if the PRG-ROM size cannot be specified correctly using the simpler notation. The actual PRG-ROM size is 2^E *(MM*2+1) bytes. If the MSB nibble is $F, an exponent-multiplier notation is used: If the MSB nibble is $0-E, LSB and MSB together simply specify the PRG-ROM size in 16 KiB units: Header byte 4 (LSB) and bits 0-3 of Header byte 9 (MSB) together specify its size. The PRG-ROM Area follows the 16-byte Header and the Trainer Area and precedes the CHR-ROM Area.

#Nes xevious rom code

Such as early RAM cartridges and emulators, and which put some additional compatibility code into those address ranges. It is only used by some games that were modified to run on different hardware from the original cartridges, It is always 512 bytes in size if present,ДЄnd contains data to be loaded into CPU memory at $7000. The Trainer Area follows the 16-byte Header and precedes the PRG-ROM area if bit 2 of Header byte 6 is set. When Byte 7 AND 3 =3: Extended Console Type If the shift count is zero, there is no CHR-(NV)RAM. ++++- CHR-NVRAM size (non-volatile) shift count

|||| ++++- CHR-RAM size (volatile) shift count If the shift count is non-zero, the actual size is

If the shift count is zero, there is no PRG-(NV)RAM. ++++- PRG-NVRAM/EEPROM (non-volatile) shift count |||| ++++- PRG-RAM (volatile) shift count |||| || 0: Nintendo Entertainment System/Family Computer |||| | 1: Present between Header and PRG-ROM data |||| ||+- 'Battery' and other non-volatile memory |||| ||| 0: Horizontal or mapper-controlled |||| |||+- Hard-wired nametable mirroring type If (iNESFormat=true & (header&0x0C)=0x08)ДЄ NES 2.0 file contains a sixteen-byte header, followed by Trainer, PRG-ROM, CHR-ROM and Miscellaneous ROM data.Д -3 Identification String.

If (header='N' & header='E' & header='S' & header=0x1A) A file is a NES 2.0 ROM image file if it begins with 'NES' (same as iNES) and, additionally, the byte at offset 7 has bit 2 clear and bit 3 set: