Sky Jinks

[glurk]

Just curious about this one.  I'm doing some 8-bit ports, and this one came up.  SO - just for the sake of curiosity, and because I'd like to look at it, has anyone done a disassembly of this old Activision title.  I searched around, even looked for Distella CFG files, and didn't find anything.  Not that I need another major project at this time, but I certainly wouldn't want to re-do something that was already done.  Is this one "out there" somewhere?  Thanks!

 

[glurk]

No response, so I made up a CFG file and DiStella'd it.  Really easy, as it's just 2K.  No comments added at all, it's just the bare disassembly.

 

Maybe someone will want to do that, LOL.  :)  Maybe I'll get around to it if no one else does.  I think it would be kind of cool to port to 8-bit, I've never seen anything on the 8-bit quite like it, with that particular type of vertical gameplay.

 

SkyJinks.asm

[+SpiceWare]

You can get better results with Stella.

1. load the ROM
2. play the game*
3. hit ` to enter the debugger
4. type savedis in the prompt

* the more things you do the better as it helps Stella figure out what each section of ROM is used for. If it knows something's used for graphics it will output it in a different format that makes it obvious what the graphics are.

 

Sky Jinks (1982) (Activision).asm

 

 

Stella's debugger:

 

 

Starting at F5FA for both, DiStella on left and Stella on right:

 

 

I created custom mode file for jEdit that colorizes binary values - it really makes graphic data pop in your code. You can learn more about jEdit in my blog.

 

 

 

 

[glurk]

Gadzooks!  I'm way behind the times, I had no idea Stella could do that!  Thanks!!  That's ENORMOUSLY helpful.

[glurk]

Incidentally, this one seems like a really underrated game (to me).  It's so smooth and pretty with the "artificial perspective" using shadows, and it has a sort of "late collision detection" so you can fly behind things.  And I haven't seen that done a whole lot, maybe ever.

 

I'm actually kind of surprised that those techniques haven't been used more often, it creates a cool 3D effect (in my opinion).

 

[Thomas Jentzsch]

Fully agreed, I was always impressed by the visuals too.

[+SpiceWare]

Off the top of my head Desert Falcon and Zaxxon both use shadows for a 3D effect, though not as impressively done as Sky Jinks.

 

 

 

 

[Thomas Jentzsch]

Yes, but Sky Jinks just a 2K game. And the main kernel is extremely clever. Use Stella's debug color mode to find out.

[+SpiceWare]

Agreed.  I recall looking at it before and was impressed that the objects (but not the plane) were all drawn using the ball and playfield.

Just checked again and forgot about the balloon using a missile to round out its shape.

[glurk]

This is not specifically about this game...  But say that I want to use Stella as an "interactive disassembler" and I want to change the RAM labels, like change "ram_80" to "frameCount" etc, etc, and then have 'savedis' save a disassembly with the more meaningful labels.

 

I can't figure this out, the label field appears to be read-only?  Because, my gosh, if it can't do this (?) what a great feature that would be.  Also to modify the SYM file on the fly.  This would make creating a disassembly a million times easier.

 

Maybe it already can do this, but I can't seem to figure out how...

[Thomas Jentzsch]

36 minutes ago, glurk said:

Maybe it already can do this, but I can't seem to figure out how...

No, Stella can't do this.

 

And since Stella's disassembly is based on DiStella, which is very limited, we probably would have to rewrite the disassembler from scratch. But feel free to create an issue on Github. Eventually we may come back to the disassembler and then it is good to have all issues and feature requests recorded.