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it's too bad python's ctypes doesn't support 16-bit x86. it'd be handy right now

my latest bad idea: DUMBPATCH.

to avoid the complexity of generating functions and mapping them into the address space of the emulated PC, I instead designed a simple syntax:

a 16bit segmented address plus a number. that function is emulated as if it returned that number in AX. There are no other options. I suspect I'll be able to emulate up to 80% of complex subfunctions with this one bit of functionality

I need this because the decompression routine I'm emulating isn't entirely standalone: it calls malloc() at the beginning and free() at the end

so I'm replacing malloc() with a static value and free() with a return value no one will check

ideally I should be able to patch arbitrary python in there and do some kind of interop to return values to python

but that's hard. and way easier unflexible thing this is 80% of what I need that for

I forgot about callee cleanup. fucking stdcall is callee cleanup. I can't have a generic int blah(){return 0x1234;} function because it needs to know how many words of arguments were pushed.

RELOCATIONS!!!! *shakes fist at sky*

I took a look at the 1985 version to see if it had any other graphics command line options (it doesn't), but I did discover in passing that it uses a different pronoun system than the 1990 Enhanced version!

It uses @0 for "He/She", @1 for "he/she", and @2 for "his/her".

hacking a computer system by changing my pronouns to they/them so that it'll use up more memory composing strings referring to me and overflow the buffer

Where in the World is Carmen Sandiego? (1985) has an invert-y-axis option for the joystick, just in case you want to use flight simulator controls to navigate a menu

back on hacking Enhanced, DOS, 1990.

My best guess is that this game has between 4-6 compression algorithms, depending on how you count them. Possibly more are hidden in the bowels of this program.

that may be only the IMAGE compression algorithms, and they use a separate different compression algorithm for text.

everything is going WONDERFULLY

this is not the game to do it with, but I really wanna try swapping out the drawing routines for one of these games once. go into a VESA mode where I can run at 1024x768 or something, and just make the drawing write to that buffer instead. Could I make BIGSCREEN DOS GAMES?

maybe I'll try it with railroad tycoon sometime. that game has loadable graphics modules. if I figure out enough of how it works, I could write my own driver for VESA Railroads

I want a girl with a short skirt and loooong BUTTONS!

hah, I love DOS programmers.
This code mallocs 65516 bytes in a loop until malloc returns zero.

totally normal part of starting program: allocate all the RAM in the system.

I mean, it's DOS. There's nothing else running that could possibly call malloc. So why not?

You also have to remember that it's not going to succeed more than, like, 6-8 times?
There's just not that much memory in the system that this can touch, since it's not supporting any of the endless varieties of breaking the 640k barrier

there's a story on Old New Thing somewhere about Windows 95 accidentally breaking a DOS game, because it did this same trick of allocating all the memory, but since Win95 was running as the DPMS, it meant it had access to all of windows 95's virtual memory. including the swap.

So instead of mallocing all 8mb or whatever your 486 had, it malloced all that and then tried to use up YOUR ENTIRE HARD DRIVE, slowly.

And then it crashed because it didn't expect to succeed that many times. It had a fixed array of handles to memory, and it overflowed because it was run on a system with HUNDREDS OF MEGABYTES OF RAM, which is clearly impossible and unthinkable

I think the solution was that win95 just defaults DOS programs to maxing out at 16mb. It won't let them allocate more than that unless you adjust the EXE options

this game runs mostly in a 16 color mode, with some high-end modes being basically 16-colors within 64 or 256 colors, right?

SO WHY DOES IT USE 16-BIT INTEGERS FOR COLOR INDICES?

I'm not sure if anyone has ever designed a paletted graphics system that uses more than 256 colors. Probably at some point someone thought it was a good idea.

note to self: patch out the Romani slur in one of the hints for Budapest

EDIT: both of them

This game was released in 1990 but it has a hint that refers to the currency of Brazil as the "cruzado". But in 1989, it had been replaced by the cruzado novo. Clearly someone was using an out of date encyclopedia!

(Brazil has had 3/4 currency changes since then, depending on how you count it)

I'm thinking of dumping a list of all the hints in this game and calculating how many of them are wrong by now.

like, most of the flag clues. do you know how many countries have changed their flags since 1989? LOTS OF THEM

The description of Hungary says it's bordered by Czechoslovakia, Austria, Yugoslavia, Romania, and the Soviet Union.

Two of those are still right!

so I fly into Reykjavík, and immediately sleep for 8 hours. In the morning, I can go to either the airport or the hotel, but it'll take 3 hours to get to either.

Question: where am I right now, if I'm not at the hotel or the airport?

They initialized the SoundBlaster DSP backwards.
You're supposed to send a 0 to the reset port, wait 3 microseconds, send a 1, then wait up to 100 microseconds for an 0xAA to show up on the data port.

They instead send a 1, then a 0, then immediately start trying to read the data port.

they read from the ports instead of measuring time, because that'll take a certain amount of time on x86. I'm too tired to confirm if their timing logic is sound. It's possible they're just assuming the PC is slow enough that it'll wait long enough

I bet broderbund bought this sound code. It feels completely different: This was either compiled on a different compiler or was written in assembly.

yeah a compiler doesn't just start using CF to return bools instead of AX. This is assembly.

they're passing single bytes to functions! C widens integer parameters to a word, so on a 16bit system, they're passed in 16-bit registers.

they're sending a... internal soundblaster test command?
(DSP 0xF0)

I dunno why this code is like this.

I suspect there may be an issue here: I identified a variable as containing the Soundblaster IO port, right? and I'm assuming everything that uses it is Soundblaster code.

But it may just be "soundcard IO port" and there's other sound device code mixed in here. So that's why some of it doesn't make sense as soundblaster, it's actually tandy 3voice or something

I just found a function (inside another function!) that's a fixed delay. How long is it?
it's a loop that runs 256 times!

that's so cute that this code considers "256 instructions" to be a meaningful length of time.