52 replies to this topic

[sometimes99er]

Take a cartridge like the 2600 Adventure, and there’s numerous “hacks” (someone changed the original binary). Some of which have just changed graphics, but some may have changed sounds, maps, number of lives, and beyond changing data, some may even have changed code.

I thought about speeding up Pac-Man/Ms. Pac-Man, or changing graphics, colors and more with TI Invaders.
Also I thought about a utility to have maybe a definition file for each cartridge locating “objects” like graphics, sprites, colors, sounds, text, invulnerability etc., and then the ability to easily “inject” changed objects.

Anyway, I ripped TI Invaders graphically. I start out with an 8K ROM and one 8K GROM.



Now it looks like the ROM is only 4K (same chunk repeated). I expected the GROM to be 6K, but then almost 1K looks rather empty. The last 2K obviously being “leftovers” and looks like intertwined repeats.

Well, just thought I’d tell you.

I’m having a few ideas about a hacked TI Invaders. Should have a twist, be slick and fun too.

[OLD CS1]

Looks like you have easily found the majority of the game's graphics.  Might be able to hack a special version.  If you do happen to make Pac-Man faster, that would be pretty neat.  Personally, I would love to fix the crappy music Atari gave us.  Meh, too late and too much work to think coherently.

[Stuart]

Just making sure you know that commented assembly source code for a disk version of TI Invaders is available ...?

[OLD CS1]

Stuart, on Tue Jul 3, 2012 6:54 AM, said:

Just making sure you know that commented assembly source code for a disk version of TI Invaders is available ...?

Where is the fun in that, I ask you?!  

[sometimes99er]

Stuart, on Tue Jul 3, 2012 6:54 AM, said:

Just making sure you know that commented assembly source code for a disk version of TI Invaders is available ...?

Yep, thanks, might come in handy. Think I’ll use Classic99 Debugger breakpoints for as much as I can - the practice there might be good for some other hacks.

[sometimes99er]

Just cut the ROM to 4K and the GROM to 6K and even 5K. Everything seems to work just fine with Classic99, Win994a and MESS.

[Stuart]

OLD CS1, on Tue Jul 3, 2012 8:21 AM, said:

Stuart, on Tue Jul 3, 2012 6:54 AM, said:

Just making sure you know that commented assembly source code for a disk version of TI Invaders is available ...?

Where is the fun in that, I ask you?!  

Exactly!

[Tursi]

Should note that as far as I know, no TI GROM was ever more than 6k - that was the memory size of the chips they made.

[sometimes99er]

Tursi, on Tue Jul 3, 2012 5:29 PM, said:

Should note that as far as I know, no TI GROM was ever more than 6k - that was the memory size of the chips they made.

Yep. Funny thing to "waste" 2K in the memory layout. Maybe chip design and method was easier to manufacture and protect.

[sometimes99er]

A memory dump from Classic99 put through Limelight (has to get colors too soon) shows a bit of the techniques used with TI Invaders. Invader graphics are, aside from being animated, pre-shifted in GROM and copied to VDP. One character set (8 characters across) is one color (one foreground and one background) basically making up one invader, but then the second line has the invader going down half a line (4 pixels), used both in the game, but also with “game over” when the invaders jump up and down intoxicated by victory.

Also notice the smileys, not only in GROM but copied to VDP too. Never seen them appear in the gameplay.

Edited by sometimes99er, Wed Jul 4, 2012 1:22 AM.

[retroclouds]

Just for fun, the source code of TI-Invaders is available as PDF in the development resources sticky thread.

[sometimes99er]

retroclouds, on Wed Jul 4, 2012 1:50 AM, said:

Just for fun, the source code of TI-Invaders is available as PDF in the development resources sticky thread.

Yep, and already mentioned (starting at post #3). AFAIK the source available is for the disk version only, but as I said, it might come in handy (if I can’t find the correct bits and bytes). Also the source is not in text (hence not being searchable or compilable). I haven’t got any OCR (Optical character recognition) software right now. Wonder if the source scan quality is okay for OCR.

[Stuart]

I've got the source already typed in and working. I'll try to upload a copy tonight.

[The source verbatim won't assemble using the assemblers we have available now so I've had to make a few tweaks to get it to work. See [http://tech.groups.y...4A/message/6947]].

[sometimes99er]

Stuart, on Wed Jul 4, 2012 5:18 AM, said:

I've got the source already typed in and working. I'll try to upload a copy tonight.

[The source verbatim won't assemble using the assemblers we have available now so I've had to make a few tweaks to get it to work. See [http://tech.groups.y...4A/message/6947]].

That would sure be nice. Also if you got it working with the Asm994a assembler.

[Stuart]

Soft copy of TI Invaders source code attached. This will assemble with Asm994a, and load with the E/A cartridge option 3 (program name SLOAD). Runs on Classic99 and Win994A. Will presumably run on the real hardware as well, but haven't tried it myself. Some more details at the top of the file.

** Retroclouds ** could you put in a copy in the TI-99/4A Development Resources sticky beneath the scanned copy in Section 7, Tutorials?

Stuart.

Attached Files

•  TI Invaders (TI-99_4A Disk Version).txt   102.25K   34 downloads

[kl99]

Before you start I suggest using the rare but known TI Invaders Version that has the 838 cheat enabled. This way your hacked version will be even more interesting for gamers.

[sometimes99er]

kl99, on Thu Jul 5, 2012 6:29 AM, said:

Before you start I suggest using the rare but known TI Invaders Version that has the 838 cheat enabled. This way your hacked version will be even more interesting for gamers.

Personally I'd rather not have the cheats, forcing the gamer to go as far as he can, if he wants to see later levels and graphics.

[sometimes99er]

TI Invaders ...



Took a look at some early Space Invaders arcades and variants. I'm quite surprised at how much the invaders share the same basic design.

Even Gorf looks much the same (in the 1st mission of 5). Changed a few things to make it fit the 9918.

[sometimes99er]

Gorf on the Coleco (using the 9918). They redesigned the invaders - don't know why.

[sometimes99er]

I didn't actually see much of the Coleco in Denmark back in the day, but there's a Danish site, so I guess something must have been going on. There's a game called Spectron and it looks like those later Space Invaders II spinoffs. Looking at the Coleco games back then, and they're generally quite big and fancy. Dragon's Lair is amazing too, but maybe only for the Adam ?

Edited by sometimes99er, Fri Jul 6, 2012 1:00 AM.

[rocky007]

i liked very much Cabbage Patch Kid, it looks like Pitfall

[sometimes99er]

rocky007, on Fri Jul 6, 2012 1:59 AM, said:

i liked very much Cabbage Patch Kid, it looks like Pitfall

Yeah, very pretty graphics, and actually both plays and looks a bit like Pitfall.

[Tursi]

sometimes99er, on Thu Jul 5, 2012 11:17 PM, said:

Gorf on the Coleco (using the 9918). They redesigned the invaders - don't know why.

That's actually Laser Attack, level 2 in the arcade Gorf. Level 1 was Space Invaders, 2 was Laser Attack (original to Gorf), 3 was Galaxian (apparently dropped in home ports), 4 was Space Warp (original), and 5 was the Flag Ship (original).
(edit: duh, ignore me here -- it's a video, not a screenshot, you saw all the stages... )

http://en.wikipedia.org/wiki/Gorf

Dragon's Lair as released was Adam only, yes, though I understand there was a port of the home computer version /programmed/ for ColecoVision but not completed.

Edited by Tursi, Fri Jul 6, 2012 1:49 PM.

[sometimes99er]

Shields have patterns, colors and positions changed.

 tiinvadershack1.zip   11.38K   29 downloads

Extract binaries for use with Classic99. Choose Cartridge menu, User, Open, - then just pick ti-invac.bin (ti-invag.bin will be included automatically).

Extract rpk from zip for use with MESS.

[retroclouds]

Stuart, on Wed Jul 4, 2012 11:21 AM, said:

...
** Retroclouds ** could you put in a copy in the TI-99/4A Development Resources sticky beneath the scanned copy in Section 7, Tutorials?
...
Stuart.

Done!

EDIT: Also gave it quick spin. Assembles very nicely.

Edited by retroclouds, Sun Jul 8, 2012 5:46 AM.