Star Raiders HD

[ClausB]

Yes, the topic title is a teaser. Not an offer, just a question:

 

Has anyone hacked Star Raiders to use a higher res mode for the starfield? It looks like ANTIC mode D now. Seems like it could be modified to use mode E with little work or mode F with some more. Anyone?

[Rybags]

Not that I know of.

 

It's only an 8K cart, so it's surprising it hasn't been reverse-engineered yet. Although, I believe someone recently posted about hacking it to eliminate certain things like Hyperpsace drift and energy drain.

 

The game was written such that it runs with only 8K RAM - probably one of the main reasons it only uses lowly GR. 7.

 

Released from the tight constraints of 8K program/8K workspace, I see no reason why the game couldn't be improved for higher resolution graphics.

 

But, it means someone doing hours/days/weeks of work, for what essentially is just a revamp/mod of someone elses masterpiece.

[ClausB]

Not that I know of.

 

It's only an 8K cart, so it's surprising it hasn't been reverse-engineered yet. Although, I believe someone recently posted about hacking it to eliminate certain things like Hyperpsace drift and energy drain.

 

The game was written such that it runs with only 8K RAM - probably one of the main reasons it only uses lowly GR. 7.

 

Released from the tight constraints of 8K program/8K workspace, I see no reason why the game couldn't be improved for higher resolution graphics.

 

But, it means someone doing hours/days/weeks of work, for what essentially is just a revamp/mod of someone elses masterpiece.

Well, I'm giving it a go. I just want to modify the starfield and leave the rest of the masterpiece as is. Also, I want to learn "from the master" how this great game works.

 

I'm using a nice tool I found by Googling. It's "6502 Disassembler for Atari" by Eric Bacher and James Wilkinson. I started with the pre-hacked STARRAID.XEX file I found on these forums. It is relocated to $4000 and has a few cheats and mods already. It's convenient but once my mods are complete, I'll apply them to the original cart image. I'm testing the mods on the Atari++ emulator by THOR.

 

The 8K ROM space and 8K RAM space are packed tight! For the ANTIC mode E display, 4K more RAM is needed, obviously. But the display list also needs to grow and there's no room in the original space, so I had to break it out into an open area. Likewise, there's a table of display row pointers that had to move as it grew. So the end product will need 16K RAM -- not a problem.

 

The bigger problem is the code space. I could find no room for patches that need extra code. The .XEX file can grow to accomodate, but the end product likely will not fit into an 8K ROM image.

 

Modifying the display list has been a bigger challenge than I expected. It is very dynamic and is often updated from small tables that also need to get modified. I'm 90% done with that but you know what they say about the last 10%. If display RAM crosses a 4K boundary, the display list needs to reload the counter. Straightforward, except that, in this case, the boundary is in the middle of a scan line. So, I have to patch that somehow.

 

The table of screen row pointers is nice because everything that draws to the playfield refers to it -- almost. The code that draws the little TIE fighter on the targeting computer does go through the table but the code that erases it does not! I doubled this table to cover the larger display RAM, but now the index into the table has to double as well. This index comes from other tables (a lot of the game is table-driven) and I have yet to learn how to use it correctly.

 

It's a challenge, but a fun and interesting one. The PC tools make it so much easier than it would have been on a pure old Atari. I'll post the result when it is presentable -- don't want to deface a masterpiece.

[Rybags]

I think you're going about it the hard way.

 

The best thing to do would be:

 

Use the original ROM for starters. Call me purist, whatever, but you'll feel more satisfaction by starting with something that hasn't already been played around with. You can always add pre-existing hacks/cheats as you go along.

 

Get it disassembled, commented, and into a state where you can reassemble it and have it work.

 

Reverse engineer it - work out what each routine does.

 

Forget about 8K - you won't achieve anything retaining an 8K ROM footprint. I'd be aiming for a program size <= 16K. RAM usage - well, 16K should be easy, but it you need 32K then so be it.

 

 

I think the hardest part, of course, would be working out such things as tables, and also rejigging all the maths and world calculations for double or quad resolution.

 

Also, there will be slowdown to contend with. I've heard that some routines in SR are optimised for space, and that there is quite some scope for improvement. So, that would probably be another side project - redevelop some of the code such that it is optimised for full speed.

[ClausB]

I think you're going about it the hard way.

You are probably right. This is taking way too much time to find the little details without understanding the whole thing. I've finally got the display list dynamics sorted, but now I'm bogged down in the target computer animation. I think I'll give it a rest for now and save it as a rainy-day project. Then I'll do what you suggest -- produce source code, understand it, and modify it instead of just patching the object code. Then I'll have my modified game plus a well-documented source for the original. The source would be more valuable to the community.

 

Whatever happened to the original source code?

Edited May 18, 2008 by ClausB

[kiwilove]

Just a few comments about the original game....

I always liked seeing the starfield effect --- but in playing the game, the moment you active your shield that nice starfield is lost with that dark green background. Maybe that's why Ace players play the game with no shields.

Anyone I would love to see a modded version, in which it is reversed - that with Shield On, it is the normal black starfield background, with Shield Off, it could be perhaps a dark red? It would make for a more enjoyable game - me thinks...

If you wanted to hack the game - you could perhaps improve (or change?) some of the graphics - like the spacebase. graphic, the robot/drone -- have a more spectacular explosion when you destroy a starbase. You could add in more damaged controls variations? There's an endless number of tweaks you can do... while keeping the basic excellent gameplays intact.. Obvioiusly if you change it from an 8K game to a 48K game - you could add some 'Star Trek' digitized sounds or 'Star Wars' etc..

 

Harvey

[Rybags]

Agreed about that ugly shield colour.

 

It'd be better to just dedicate some blank lines before/after the viewscreen and have their background colour reflect the shield status.

 

Another thing I'd do is have the computer HUD/crosshairs less obtrusive, and probably at a lower luminence.

 

ClausB - I checked that demo you sent me. Really, you can't tell much difference. Maybe consider Mode F? Problem then of course is that you lose colour ability.

Maybe use dithering tricks: If you have a pixel, blank then pixel you end up with a nice half-bright type line.

 

I guess though that using Mode F would present a whole new range of problems - for starters onscreen X co-ords suddenly need 2 bytes instead of 1.

 

Better starship - again, a possibility - doesn't the default one use just 2 players? I guess maybe a spare has to be kept incase an asteroid comes onscreen?

[doctorclu]

So how's this coming along? Just curious if we've seen more progress?

 

At least disassembly.

[Rybags]

ClausB sent me a running version some time back.

 

I think he didn't go any further, he was concerned by lack of interest.

 

Maybe it's worth a revisit - really, a source version would be handy - I reckon a remake with hires+Interlace might be worth doing.

 

The question would be - whether to go 320x480 or just 160x480.

[carmel_andrews]

Wakey wakey claus....how is it going there friend

 

Perhaps the zylon empire zapped the Aft view of his ship

 

Are you still with us Clausb

[peteym5]

I personally would not go beyond 160x192 or 320x192 mode since it may be played on TV sets. If interlace modes are used, the stars may be too small to be scene.

[a8isa1]

Just a few comments about the original game....

I always liked seeing the starfield effect --- but in playing the game, the moment you active your shield that nice starfield is lost with that dark green background. Maybe that's why Ace players play the game with no shields.

Anyone I would love to see a modded version, in which it is reversed - that with Shield On, it is the normal black starfield background, with Shield Off, it could be perhaps a dark red? It would make for a more enjoyable game - me thinks...

If you wanted to hack the game - you could perhaps improve (or change?) some of the graphics - like the spacebase. graphic, the robot/drone -- have a more spectacular explosion when you destroy a starbase. You could add in more damaged controls variations? There's an endless number of tweaks you can do... while keeping the basic excellent gameplays intact.. Obvioiusly if you change it from an 8K game to a 48K game - you could add some 'Star Trek' digitized sounds or 'Star Wars' etc..

 

Harvey

OT: Green backgrounds? That's interesting. Always been dark blue on my machines (NTSC 800 and 800XL).

 

The background color never distracted me until I did the Super Video XL mod (2.0 only) which seemed to boost blue saturation. This had the affect of making it easier to spot approaching ships with shields enabled than without. It feels like cheating.

 

I'm definitely not an 'ace' and would never think of playing without the shields. Guess I will just have to live with the enhancement (though I still keep the 800 accessible).

 

Back to the subject...

 

Claus, it might be worth doing a hi-res mockup of the starfield to see if you even like it, before you go to any more trouble.

 

- Steve Sheppard

[JokerCPoC]

Just a few comments about the original game....

I always liked seeing the starfield effect --- but in playing the game, the moment you active your shield that nice starfield is lost with that dark green background. Maybe that's why Ace players play the game with no shields.

Anyone I would love to see a modded version, in which it is reversed - that with Shield On, it is the normal black starfield background, with Shield Off, it could be perhaps a dark red? It would make for a more enjoyable game - me thinks...

If you wanted to hack the game - you could perhaps improve (or change?) some of the graphics - like the spacebase. graphic, the robot/drone -- have a more spectacular explosion when you destroy a starbase. You could add in more damaged controls variations? There's an endless number of tweaks you can do... while keeping the basic excellent gameplays intact.. Obviously if you change it from an 8K game to a 48K game - you could add some 'Star Trek' digitized sounds or 'Star Wars' etc..

 

Harvey

OT: Green backgrounds? That's interesting. Always been dark blue on my machines (NTSC 800 and 800XL).

 

The background color never distracted me until I did the Super Video XL mod (2.0 only) which seemed to boost blue saturation. This had the affect of making it easier to spot approaching ships with shields enabled than without. It feels like cheating.

 

I'm definitely not an 'ace' and would never think of playing without the shields. Guess I will just have to live with the enhancement (though I still keep the 800 accessible).

 

Back to the subject...

 

Claus, it might be worth doing a hi-res mockup of the starfield to see if you even like it, before you go to any more trouble.

 

- Steve Sheppard

Maybe You weren't, But I think I was, But It was one of My very first Games on the Atari 400 that I had back in 1980.

 

Victor

[Rybags]

Shield-enabled background is green on every machine I've seen it on... it's probably the PAL/NTSC thing.

 

We also get an annoying Purple Alert instead of Red Alert, again thanks to colour differences.

[doctorclu]

Shield-enabled background is green on every machine I've seen it on... it's probably the PAL/NTSC thing.

 

We also get an annoying Purple Alert instead of Red Alert, again thanks to colour differences.

 

LOL!! Well definately an interest to see an updated Star Raiders.

 

You say there is a working improved version? As we are encouraging Claus to continue his work on this, is there any way we can see what he has done so far?

[Rybags]

I'd like to see an interlaced version... you just need to do 2 pixel high dots and vertical lines to avoid the flicker.

 

But the big issue is that your Y coordinates then become 9 bit numbers, so it's either a case of just render with less precision or redo lots of code.

 

Breaking the game down into a Source module, I think would be a great idea.

[FastRobPlus]

I'd like to see an interlaced version... you just need to do 2 pixel high dots and vertical lines to avoid the flicker.

 

Is there anything you wouldn't interlace?

[ClausB]

Wakey wakey claus....how is it going there friend

 

Perhaps the zylon empire zapped the Aft view of his ship

 

Are you still with us Clausb

I still lurk here once in a while. Too busy with life for much Atari fun, so had nothing to post (though that never stopped me from posting before). Did read "Racing the Beam" recently - very interesting. Makes me want to try to write a 2600 game.

 

I stopped working on SR HD last year because I hit a wall in understanding the disassembly. Would be nice to peek at the source. Here's how it looks in the higher resolution of mode E.

 

The attached .XEX has my patches so far (plus some others' mods). It still has some problems, such as the stars losing vertical motion at the top and bottom, and some blinking in the middle.

 

I don't like the way the rectangular stars look in an emulator or on an up-converting monitor, but on my plain old color TV, I think they look more like pinpoints, as stars should.

SRE.zip

[+Stephen]

Wakey wakey claus....how is it going there friend

 

Perhaps the zylon empire zapped the Aft view of his ship

 

Are you still with us Clausb

I still lurk here once in a while. Too busy with life for much Atari fun, so had nothing to post (though that never stopped me from posting before). Did read "Racing the Beam" recently - very interesting. Makes me want to try to write a 2600 game.

 

I stopped working on SR HD last year because I hit a wall in understanding the disassembly. Would be nice to peek at the source. Here's how it looks in the higher resolution of mode E.

 

The attached .XEX has my patches so far (plus some others' mods). It still has some problems, such as the stars losing vertical motion at the top and bottom, and some blinking in the middle.

 

I don't like the way the rectangular stars look in an emulator or on an up-converting monitor, but on my plain old color TV, I think they look more like pinpoints, as stars should.

Thanks for sharing - I've thought in the past about a high resolution Star Raiders - the gameplay is perfect, but a hi-res color version would be cool, especially since we are WAY past the 8KB barrier.

 

Stephen Anderson

[ClausB]

Here's how it looks in the higher resolution of mode E.

Any comments from the 25 downloaders?

[doctorclu]

Here's how it looks in the higher resolution of mode E.

Any comments from the 25 downloaders?

 

Gotta hit work, but I will try it afterwards. Damn work.

 

Thanks for the upload and please continue working on this!! A dream come true.

[+Allan]

Yea, it looks fantastic on the real thing!

 

Allan

[spookt]

I was waiting to try it on real kit this weekend, but it looks nice in the emulator.

[MEtalGuy66]

Looks good, but the pitch/yaw control/movement is a bit slow.. Maybe because of the doubled resolution... could you double-step the control movement to compensate for this?

[Rybags]

I think a very worthwhile project would be to make a full disassembly and reverse-engineer and document the workings of the game.

 

It would serve a historical purpose, as well as making any mods or games based on it somewhat easier.

 

I reckon an interlaced version using Vector Graphics in hires might be kinda cool.