the game internally has 5 drivers (as of 2.2, I have other versions here and they're different): CGA, Hercules, EGA, Tandy, VGA.

WHY ARE THERE TWO STRCATS

I've been working on cities.dat. I can now confirm that this game (Where in the World is Carmen Sandiego Enhanced (DOS, 1990)) has 30 cities, and they're the same 30 cities as the 1985 original.

hmm. I could reuse my readString code between these two formats, but it would technically enable world cities to have pronouns.

this game uses a fun text encoding method: both-ended null terminated!

It stores city names with a nul at the beginning because it reads them backwards. For some fucking reason.

why in the fuck is loading the data for Paris suddenly grabbing some random data out of Kigali? this implies some weird things about the compression, or the data normalization

going to moscow loads the same byte. strange.

they seek to position X
read 1 byte
read 99 more bytes
then seek to position X+100

now if you know how both math and random access files work, you'll realize something the programmers of Where in the World is Carmen Sandiego? Enhanced (1990, DOS) did not:

THEY'RE SEEKING TO THE POSITION THEY'RE ALREADY AT

I tried to corrupt the image to see if that'd tell me anything about how it was encoded, and it told me to put my hard drive back in.

the way this game does the investigations is interesting.
so the basic gameplay is that you're in location X, you get 3 hints, which lead you to location Y, where the whole process repeats.

But if you savescum to experience the same pursuit again, they'll always go through the same places... but if you don't get the hints, they won't be there.

like the hints will always tell you to go to sri lanka, but if you go there without first having heard those hints, then he won't be in sri lanka

Hah! the game apparently calculates some info ahead of time, but only a few steps. I changed who the suspect was by memory editing, and it didn't take effect... until I got to the third location.

Since I went from a robbery by Fast Eddie B to one by Merey LaRoc, it means the pronouns changed when I got to London.

Congrats on coming out as a trans woman, Merey.

ok I ran my dosspin tool to gibberish every byte of the save game file (it's only 102 bytes, so this is easy!) and none of them change where you start. very interesting... I'm guessing either the values are spread out too much for my gibberishing to reach, or you need to modify multiple bytes at once

huh, I found a hidden(?) key: if you hold down either shift, it skips all the pauses in the printing. so it goes at MAX CPU SPEED

ahh good. it's always fun to find code that looks like:
do{

while(variable!=0);

some one has a custom tick handler that's permutating a global!

can't be threading, this is 16-bit DOS. There is no threading.

looking at interrupts, and I think I found a bug.
they set handlers for various CPU errors, but they accidentally set 10 (COPROCESSOR ERROR) twice, instead of the 05 (BOUND check)/10 (COPRPOCESSOR) interrupts they save

someone copy-pasted and missed a bit

I finally found the two helper functions they use to get and set vectors!

all the 30 other places I've seen them set/get vectors, they do it manually, but hey, maybe they use the helpers too

could also be that this is a compiler-provided bit of code, which is left in because the runtime needs it, or they just didn't eliminate dead code

okay I've figured out there's a shared format they're using here. it chunks the file into chunks, which have a 16-bit ID (unique per file, but not globally), an offset, and 16-bit length