Alice Averlong🏳️⚧️oh hello copy protection, fancy meeting you here
oh hey that's fun. this game has two layers of copy protection! if I hack the "check weird sector" code to always return 0 (for found-it), it tells me "Diskette/version out of phase"
they call the copy protection on two different sectors, and throw the out-of-phase error if they give the same result, I think
so you can't just overwrite check_copyprotection_sector with return 0
oh god they overwrite the DOS interrupt 1E in the middle, to make DOS think it's a different kind of floppy disk.
okay I now know HOW to crack the game, I just gotta write the x86 assembly.
normal people don't do this. normal people don't write 16bit DOS assembly in 2025.
I have 37 bytes. this won't be hard
and... it doesn't work.
tertiary copy protection?
tertiary copy protection?
I think they might be depending on the value of the weird sector elsewhere. like they're loading it SOMEWHERE, maybe they overwrite some code?
I need a comparative DOS CPU tracer.
Like, load two copies of the same EXE, and run until the execution diverges
THEY CHECKSUM THE FIRST 16KB OF EXECUTABLE RAM?
I patched the EXE to have the right value, but then they checksum it, and now the value is wrong!
insert pop-team-epic "you are motherfucker" here
they checksum memory MORE THAN ONCE!?
I patched out the checksumming and I think I've got it.
okay, so, the copy protection:
1. It checks for a sector that should not exist: Track 38, sector 113.
It's on a single-sided double density floppy (160kb), so there's supposed to be 8 sectors per track. But as we saw in this post:https://digipres.club/@foone/115011910054706753
this disk DOES have a sector 113.
Foone🏳️⚧️ (@[email protected])
Attached: 1 image oh hello copy protection, fancy meeting you here
so step one to bypassing the copy protection is hack that function to return "yes the sector exists".
EXCEPT THAT WON'T WORK. For two reasons. The first I'll get to later. The second is that the actual value of that sector matters, it gets read into memory and the bytes at 0x7-0x8 are checked later.
so I make sure those 2 bytes in memory are set. Easy!
the next phase of copy protection checks another sector: track 39, sector #25.
Another sector that doesn't exist, but it does, and it's 128 bytes long, and... they're doing evil things to DOS to make this readable. They switch the DOS format in memory, reset the disk IO system, and try to successfully read a 128byte sector. Somehow, apparently, this works?
I think there's another layer of protection that I bypassed on accident
trying to figure out this possible third layer of protection before I continue.
today's scores- emulators crashed:
1. DOSBOX: 2 times
2. MartyPC 1 time
3. 86Box: 0 times
okay, tracked it down: it's just coming from the same sector 113 as loaded in step one. Anyway, if this isn't loaded properly, we'll trigger a "Diskette/Version out of phase" error. I fix this by just never checking if it's loaded: I NOP'd that part out
gloriouscow@foone is this repeatable? i'd like to fix any crashes :)
ity [unit X-69] - VIOLENT FUCK@foone what about PCBox
Dianora (Diane Bruce)@foone I remember writing a TSR for an ATARI that would intercept the disk I/O calls to fake the right data returned. 128 byte sector eh? oh boy.
jmj
Maki 🔻 🌹@foone They probably studied at the California Institute of the Arts: https://en.wikipedia.org/wiki/A113
Gemini6Ice@foone checkmor, if you will
I love this, so I@foone they were VERY serious about their anti-piracy and anti-cheat measures.
mmu_man@foone 🎶 Too many sums, too many sums… Too many sums, too many sums…
Matt Palmer@foone I am behind seven checksums, I am uncrackable.
Athena L.M.@foone copies protected
Rue Mohr@foone so just make the last instructions in the checksum code return the value they want, or NOP the branch that would say otherwise.
dr. fennec 
@foone as a treat
Geoff 🏴@foone Cosmic ray detection?
Aaron Sawdey, Ph.D.@_thegeoff @foone 🤣 Exactly what I was going to post: "You're inventing a particle detector"
Very Human Robot@foone actually that would be pretty rad!
Bloognoo@foone sync function stepping between two DOS boxes and xor the output?
Sentry23@foone Remind me so much of old 68k protections on late ST games.
Jay it works. Wait, why can't I control anything on level 2...
Mendie 
37 bytes , I'm not sure if facetious or
Molive
Fuchsiii~~~@foone .... but I do have a book about it!
Cloudmom Colette
vfig@foone seems perfectly normal to me. its only a few weeks ago that i was writing some 16 bit assembly in debug . com so i could call absolute it from qbasic . com
Petherfile@foone don't be normal. Totally overrated.
Phil M0OFX@foone Fun people on the other hand...
Leah 
@foone meanwhile, the foone at work: 
F4GRX Sébastien
Nuclear OatmealSecurity via obscurity is a _type_ of security.
Kawaoneechan@foone True. Last time I wrote 16 bit DOS assembly was last year.
It was to detect sound cards.
J.V.B.@foone Your reference point for normal people seems to have become like https://xkcd.com/2501/
wyatt@foone thankfully you're abnormal
Spindley Q Frog@foone that was mostly a 2023 thing for me, true
Brian Danger Hicks@foone Yeah but have you seen what passes for normal in 2025?
?@ity yeah, close enough!
Garth KiddNORMAL PEOPLE DON’T
… like it when anyone labels or describes normality from the outside. That’s for them, not for us, and pointing that out will test the nerves of even the most ardent of allies. Listen here, you little shit, don’t ever treat us like we treat yo—
Feeling riled, any? Do tell.
All of which, I mention only to give context for my chain of reactions to the mental image of a “normal people don’t” T shirt:
1. MAY, because funny
2. SHOULD NOT, because confronting
3. MUST, because confronting
Indigo 🏳️⚧️
@foone which game?