flashing/cycling backgrounds

[gimbal]

Ever since I owned an Amiga I have been wondering about something: what's with all the colour cycling backgrounds in amiga games?

If you don't know what I'm talking about, I attached a screeny. That one is specific to last ninja remix, most games have their own specific form of flashing (different colours, thickness of lines, movement of the lines).

Now it seems that it is something that is mostly specific to cracked games, but I have seen it used also when the game wants you to swap disks (or is that also because the game was cracked and the disk swapping code was changed? Hmmm...). I could be wrong of course, maybe it's not related to cracks at all.

What is the use for it, next to giving you an epileptic attack? If it was just random it would have stuck to only a few games, but there are just to many that have it... What secret am I missing?

[Codetapper]

It's a common display mechanism used in crunchers to show that the program has not crashed. Often the original game held more data than a normal disk, or the game was encrypted and the crackers simply grabbed the file after it had finished decrypting. These files were usually pretty big and in the age of 2400 baud modems, the files had to be packed.

Since depacking is quite slow on a 68000 and could sometimes take 10 seconds to depack 512k, the crackers probably figured some people would think that game had crashed if the screen stayed black, so added a line like:

move.w d5,$dff180

in the main loop of the depacking routine. That flashes the background with whatever word is being written into memory causing the flashing you see.

Note that there are actually a lot of commercial games that use the exact same packers the crackers did *but* they often removed the flash instruction so the display would stay black. Almost all of my WHDLoad installs that use cracked files I remove the flashing from as it's very quick if it's in fast memory and looks more professional.

[Galaxy]

If you love in-game colour cycling (not the decrunch stuff) check out Super Gridrunner!

i remember a while back I transfered one of my original amiga games to adf format on my pc ran the game in the emualtor and seen a similar a result at first i thought something when wrong with the transfer proccess but later discovered it was the kickstart i was using. It appears this game needed a specific kickstart to run in the emulator and if you were using the wrong one like i was the flicky colors would appear and the game would halt i wonder how many other games have this feature

[plasmatron]

The game with the longest decrunching ever, was the cracked version of Codemasters MIG29 Sowiet Fighter.
http://hol.abime.net/2472

The decrunching takes over a minutes. No joke.

It was an Angels crack

[Ironclaw]

Originally Posted by Galaxy

If you love in-game colour cycling (not the decrunch stuff) check out Super Gridrunner!

Or play C64 games.

[Phiber]

Originally Posted by Ironclaw

Or play C64 games.

Definately. Real machine. With a tapedrive. Use tape turbos and see the spectrum of pretty little flashes..

Hehe.. back when i was a wee little lad, and i just had my first c-64 with a tapedrive, i used to know exactly at which point the game was loading by looking the turbotape flashing on the screen.. I still remember what Uridium looks like even today, because i used to play it atleast once a day..

How about speccie's ....
I remember booting commando for like half an hour or so...
Not to mention Friday the 13th !!!

[gimbal]

Originally Posted by plasmatron

The game with the longest decrunching ever, was the cracked version of Codemasters MIG29 Sowiet Fighter.
http://hol.abime.net/2472

The decrunching takes over a minutes. No joke.

It was an Angels crack

Actually, I remember a gods demo disk that took three minutes or so (that's three minutes worth of flashing) :s I think it was Amiga Power.

But thanks for the info people, another mystery solved for me!