Kickstart ROM Checksums

vimfuego · 18 September 2009, 07:00

Hi All,

Not sure this is the right section for this question

Looking at a Kickstart ROM .bin file (3.0 as an example), the 32 bit checksum value is at $7FFE8 ($8B56E930), how is this calculated?

Thanks,

thomas · 18 September 2009, 07:41

Not sure about the Kick ROM, but usually if AmigaOS uses a checksum, it is choosen so that the sum of all longwords (including the checksum itself) calculates to 0. This means the checksum is the negative result of adding all longwords except the checksum itself.

Adding is done without taking overflow or carry flags into account.

18 September 2009, 07:00	#1
vimfuego Registered User Join Date: Apr 2009 Location: Melbourne / Australia Posts: 68	Kickstart ROM Checksums Hi All, Not sure this is the right section for this question Looking at a Kickstart ROM .bin file (3.0 as an example), the 32 bit checksum value is at $7FFE8 ($8B56E930), how is this calculated? Thanks,

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18 September 2009, 07:41	#2
thomas Registered User Join Date: Jan 2002 Location: Germany Posts: 7,002	Not sure about the Kick ROM, but usually if AmigaOS uses a checksum, it is choosen so that the sum of all longwords (including the checksum itself) calculates to 0. This means the checksum is the negative result of adding all longwords except the checksum itself. Adding is done without taking overflow or carry flags into account.

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