Impossible Mission weird-ism

[+Propane13]

An interesting find:

 

When you get home (if you're already there, then great!), pop in 7800 Impossible Mission.

 

Get to the room with the ORB, and the lift in the center of the room, and no robots. http://home.arcor.de/cybergoth/epyx/impyellow7.gif

Once here, go to the bottom right-hand corner. Search the toilet paper and the toilet. Then, spastically, start pressing up in random places (stay on the right-hand side of the elevator). Usually, it's best to search where the toilet was. If you're lucky, it'll one of these times say "searching", and the meter will go down. Then, when done, the bathtub ON THE LEFT of the elevator will disappear. I'm wondering if:

1) this bug exists in the PAL version

2) this is replicatable by someone else (I've done it twice)

3) this works in other places? Maybe its a good trick for those "hard-to-reach" areas with psychotic robots.

 

Thanks,

-John K. Harvey

[Eckhard Stolberg]

I have tried it with my PAL version, and it works there too. The room is green in my version though. I didn't have time to try this trick out in other locations, so you'll probably have to figure out the answer to your 3rd question on your own.

 

BTW, do you (or someone else) have the possibility to do a screen capture of Atari's colour tester program on a real PAL and NTSC 7800? That might help figuring out the differences in the colour translation table, that you mentioned.

 

 

Ciao, Eckhard Stolberg

[+Mitch]

Well, I could do it for an NTSC console. Unfortunately, my capture card doesn't handle PAL.

 

Mitch

http://atari7800.atari.org

[Albert]

quote:

---

Originally posted by Mitch:

Well, I could do it for an NTSC console. Unfortunately, my capture card doesn't handle PAL.

---

 

If you can capture it, I'll throw the video up here on AtariAge..

 

..Al

[+Propane13]

From Eckhard's earlier posting (and I think in the dev manual, though I don't remember where), we get:

 

NTSC PAL

$0x $0x

$1x $3x

$2x $4x

$3x $5x

$4x $6x

$5x $7x

$6x $8x

$7x $9x

$8x $ax

$9x $bx

$ax $cx

$bx $dx

$cx $ex

$dx $fx

$ex $1x

$fx $2x

 

From color changes in Impossible Mission (that have been fixed so far), I get:

 

(note that PAL and NTSC headings are inverted from above)

 

PAL NTSC OCCURances

$0x $0x 1

$1x $Ex 2

$2x $Fx 4

$2x $1x 2

$3x $2x 8

$3x $Fx 1

$3x $3x 1

$4x $3x 6

$4x $2x 2

$5x $4x 6

$6x $5x 4

$6x $6x 1

$7x $6x 1

$8x $7x 5

$9x $8x 3

$ax $9x 5

$bx $ax 2

$cx $bx 3

$dx $cx 4

$ex $dx 1

$fx $ex 2

 

So it looks more like:

{

If 0x, then 0x

If 1x or 2x PAL, then Ex and Fx NTSC accordingly

All Else PAL = 1 MS Nibble less for NTSC

}

 

Definitely interesting. I think it would be cool to try and figure out an optimal table.

 

Thanks,

-John K. Harvey

[+Propane13]

Eckhard,

 

I have access to a digital camera via a friend (which could give differences due to television hue/etc...), but that would be a preliminary way to do it. No screen capture tools--- yet

 

I've also got a palette table that I've created based on Impossible Mission palettes which I will post here in a little while (once completed). I'm sure that would be useful input to feed into this investigation.

 

-John K. Harvey

[jindroush]

quote:

---

Originally posted by John K. Harvey:

From Eckhard's earlier posting (and I think in the dev manual, though I don't remember where), we get:

---

 

That table is not correct - lots of blue colors are green then.

 

quote:

---

From color changes in Impossible Mission (that have been fixed so far), I get:

---

 

I just implemented PAL emulation in MESS and from disassembly of few PAL/NTSC counterparts I made table which goes off by one until 0x05, skips 0x06 and then goes off by two. That doesn't look that bad, but is not perfect (probably because there is no one by one conversion).

 

BTW: I made something I think is fixed NTSC version (not PAL->NTSC, but NTSC->NTSC) of Impossible Mission with simply patching 4 bytes in one place and cca 200 bytes in another as I described in my previous posting on that topic. Anybody with a burner wants to try that version?

[Eckhard Stolberg]

There only is a conversion table for the 2600 in the readme file. The table above was created by me fom comparing the output of my 7800 with the output of MESS. The colours in MESS seem to be much more intense than on my PAL 7800 though. That makes finding properly matching colours a bit difficult. Therefore it would be great, if you (Mitch) could capture the output of the colour test program on your NTSC 7800.

 

Looking at your (John) new table, I'm not quite convinced either. It's probably just as much off, as mine was. But if the intensity of the PAL and the NTSC 7800s really differ so much, that might explain why the programmers were not able to find one-on-one matches, as your research with Impossible Mission shows.

 

 

Ciao, Eckhard Stolberg

[+Mitch]

OK, I burned the color test program to an EPROM and put it on a cart. I was just looking at it again and realized that there are 256 possible screen colors! Did you want all of them? That could take a while. If you just want a few particular colors I could probably do that over the weekend.

 

Mitch

http://atari7800.atari.org

[Eckhard Stolberg]

I'd like a screen shot of all colours, if possible. But Atari's program should display all of them on the screen at once. Wouldn't doing one screen shot of this display be enough, or are there some problems with capturing it?

 

 

Ciao, Eckhard Stolberg

[+Mitch]

OK, I took three screenshots. They didn't turn out as well as I had hoped. I guess I really should do the S-Video mod one of these days.

 

Anyway, here they are:

http://members.aol.com/~Atari7800games4/color1.jpg

http://members.aol.com/~Atari7800games4/color2.jpg

http://members.aol.com/~Atari7800games4/color3.jpg

 

I hope they're good enough.

 

Mitch

http://atari7800.atari.org

[Eckhard Stolberg]

Thanks for posting the screenshots, Mitch. Creating a better emulator palette from them might be pretty difficult, but at least I now have a better idea of what the NTSC palette really looks like.

 

 

Thanks, Eckhard Stolberg