Ancestors

Written by Foone🏳️‍⚧️ on 2025-01-02 at 06:26

tandy put their sound chip on the 1A interrupt? THE TIME SERVICES?

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 06:27

I started reverse engineering Where in the World is Carmen Sandiego (Enhanced DOS edition) and I'm trying to find how it generates its random seeds so I search on int 1a and the first thing I find is it's doing TANDY SOUNDS?

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 06:38

Funny fact: I was trying to get an online assembler to spit out the machine code for "int 1a" but couldn't get it to, so I just went "fuck it, I can probably just do that in my head!"

Turns out I can. My brain is weird.

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 06:56

Here's something I didn't know existed until just now: Where in the World is Carmen Sandiego checks your name against the list dossier list and rejects you if you use any of those names.

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 07:01

PRONOUNS DETECTED: THIS GAME IS WOKE

sadly they don't have they/them on here. What about the non-binary criminals, huh?

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 07:03

stretch goal: hack in at least on enby criminal with appropriate pronouns. maybe I'll just put myself in the game as one of the criminals you can apprehend

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 07:22

I faked this screenshot but this is what I mean

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 07:30

I think I might be able to do the hack I want by changing one byte.

I'm trying to change it so it has "daily challenges", and I think I can fix that by just switching a INT 1A from subfunction 00 to 04, making it seed the random function with the date instead of the ticks-since-midnight

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 08:06

eh, I used 5 bytes. I don't need to impress anyone

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 09:52

NORMAL CODE

random(*(byte )(undefined2 *)

                   (*(int *)(*(int *)0x39a6 * 0xe + local_c * 2 + 0x1d02) * 2 +

                   *(int *)(local_c * 2 + 0x24b)) - 1);

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 09:55

I found another set of pronouns!

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 09:56

I haven't figured out how this game stores gender, but I'm gonna go out on a limb and say it's like this:

male: 0

female: 4

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 09:59

why? because they have strings like:

char* HE="He\0\0She\0"

char* HIS="His\0Hers\0";

char* HIM="Him\0Her\0";

so they can do like:

printf("Follow %s to %s lair, and capture %s alive!", badguy->name, HIS+badguy->gender, HIM+badguy->gender);

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 10:00

I like how the game only asks your name, not your gender.

Player's don't have genders. Only thieves have genders.

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 10:01

It's a prequel to Disco Elysium, and your gender is set to COP

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Written by Foone🏳️‍⚧️ on 2025-01-02 at 10:33

why does ghidra's "search by instruction pattern" default to BINARY?

what kind of a freak remembers the machine code for INT 21 on x86 in BINARY?

it's CD21h, not 1100110100100001!

what are you, some kind of nerd?

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Toot

Written by Chartreuse on 2025-01-03 at 14:07

@foone clearly we need the compromise of octal. 315 061

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Descendants

Written by Foone🏳️‍⚧️ on 2025-01-03 at 14:26

@ChartreuseK not even supported by this ghidra dialog. Binary or hex are the only options.

And note the weird part where it's "search by instruction pattern" but typing in instructions isn't possible.

You need the machine code for int 21h, not just "int 21h"

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