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Raiders of the Lost Ark

2600 conversion

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#1 phaeron OFFLINE  

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Posted Sun Jan 1, 2017 6:15 AM

A little conversion for the new year -- a port of the 2600 game Raiders of the Lost Ark to the 8-bit. It's not one of the most graphically intense games, but it's one of my favorites as I always thought of it as a more advanced Adventure. It requires 48K of memory, but should run on an 800.

 

Most of what is in the 2600 manual applies, except the B&W switch... which didn't work even on the 2600. Press Start to restart the game. The original game had a clunky two joystick setup where player 1 controlled the inventory and player 2 controlled Indy. This works in the conversion, except reversed so that joystick 1 controls Indy. Two other control schemes are now supported. The keyboard can be used to control the inventory, by ,[ and .] to move the cursor and space to drop items. You can also connect a Genesis 3-button gamepad and hold down the C button to control the inventory, with B being the regular action button. The gamepad must be connected when pressing the action button to start the game from the Well of Souls for the game to recognize it.

 

Conversion notes:

  • The original cartridge is an 8K banked cartridge. It about doubled during conversion because I expanded a lot of playfield data; it could probably be crunched down a lot since the playfield data is very sparse. The original code/data is all relocated down, but there are still some places in code where the high address byte for data is hardcoded.
  • Raiders doesn't use replication, but it uses HMOVE a lot, and worse, has no less than four different display kernels which use a 'display list' to drive both player 0 and several different hardware registers. I basically had to totally rewrite three of them. One annoying GTIA issue I ran into: can't detect collisions between missiles. Bad if you're emulating the ball with a missile and then find a M1-BL collision check in the code.
  • I spent more time verifying the graphics this time against the original game in Stella and it should largely match the 2600 version pixel for pixel. This was needed because the map room actually became unplayable if the VDELAY settings on the sprites weren't just right. Notable deviations: the left basket in the marketplace is a scanline off because of a timing issue in the display kernel and the lower temple entrances aren't squared off when the doors drop; those were too much of a pain and too minor to bother fixing.
  • The sound driver in the game is primitive, but the way it does sound effects is amusing -- it writes the same value for frequency and distortion.
  • No PAL speed compensation this time -- Raiders relies a lot on playfield collisions and some of the position checks and level boundaries would probably break if Indy could move faster than one pixel per frame, so just running the vertical blank processing 6/5ths faster won't work. Color compensation is also difficult because colors are embedded in the display lists.
  • All secrets and most bugs should be replicated, including the Yar and the signature. A couple of bugs didn't carry over because they are caused by wigging out the TIA sprite placement (walking off the right side).

indy.png

 

Attached Files



#2 Mclaneinc OFFLINE  

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Posted Sun Jan 1, 2017 6:29 AM

Ha ha...I thought you had been a little quiet...

 

Thank you so much for another excellent port...

 

All you need to do now is integrate 2600 and 7800 emulation, I give you a week to do it in :)

 

Seriously, thank you for the new year present...



#3 Heaven/TQA ONLINE  

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Posted Sun Jan 1, 2017 6:44 AM

Cool.... remember playing it as kid... standing at top of mountains and waiting for the sunset...

#4 macdlsa OFFLINE  

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Posted Sun Jan 1, 2017 10:45 AM

Hi there.

I'm not used to 8-bits Atari computers since I'm "only" a fan of the VCS...

Filippo "Philsan" told me there's that porting, and... oh, well, RotlA is one of my favs since the 1983, so... heh, I've just tried it ;) !!!

I played it on Altirra emulator and I could say the game is pretty much the same as the one already seen on the VCS  :thumbsup: !

.. with ALL its original gameplay (although the controls respond a little bit "laggy", but I think it's due to the emulation...) and, yep, also the two Easter-eggs !

 

:thumbsup:  :thumbsup:  :thumbsup: !!! Really a nice job !!!  :thumbsup:  :thumbsup:  :thumbsup:

 

I post here some videoclips, directly recorded from the emulator window (and, let me say it, it's a feature which would and should be implemented in every emulator... ;)  :thumbsup: ) to show you some "highlights" of a "full-game" with the 2 easter-eggs shown and the top-score of 20.5 "steps" !

 

> Clip 1 only shows a little "glitch" (if we could call it "glitch") in the timepiece... that "line" you can see on the right/up side of the entrance

 

> Clip 2 shows the 1st easter-egg, the "Yar"

> Clip 3 shows the Map room and the Ark position in this game

 

> Clip 4 shows the discovery of the Ark, the second easter egg (HowardScottWarshaw initials + "2" as it's his second game) and the Top-Score of 21 "steps"



#5 suspicious_milk OFFLINE  

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Posted Sun Jan 1, 2017 11:43 AM

Awesome!!!  Thank You.  I love RotLA and ET style games and I've always wanted this on A8!



#6 Triads OFFLINE  

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Posted Sun Jan 1, 2017 1:47 PM

Excellent.. I think I still have my handwritten walkthrough I did as a kid..



#7 phaeron OFFLINE  

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Posted Sun Jan 1, 2017 3:37 PM

> Clip 1 only shows a little "glitch" (if we could call it "glitch") in the timepiece... that "line" you can see on the right/up side of the entrance

 

Which emulator version are you using? I can only reproduce this with an old version of Altirra (<2.40).



#8 Poison OFFLINE  

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Posted Sun Jan 1, 2017 9:17 PM

Wow! great conversion, thank you very much for that! :thumbsup:

 

Just question . . is possible to convert Double Dragon or Kung-Fu Master or Frosty from A2600 too?


Edited by Poison, Sun Jan 1, 2017 9:18 PM.


#9 macdlsa OFFLINE  

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Posted Sun Jan 1, 2017 10:12 PM

 

Which emulator version are you using? I can only reproduce this with an old version of Altirra (<2.40).

 

Right, Sorry... I forgot to mention I use Altirra 2.30... :woozy: [pic] Atari800_RotlA_TimepieceGlitch(Altirra2.30).png

I got your latest 2.81 right now, but I'm goin' to work... I think I could try it in the evening  :thumbsup: (maybe it will solve controls delay, too...). 

 

And, I was wrong saying the top score is 21 steps... in fact I would say it is 20.5 steps and I've never been able to do better.



#10 phaeron OFFLINE  

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Posted Sun Jan 1, 2017 11:30 PM

And, I was wrong saying the top score is 21 steps... in fact I would say it is 20.5 steps and I've never been able to do better.

 
The highest possible score is 20.25 steps, and the lowest possible score is one step. The complete scoring algorithm:

Spoiler

 



#11 eegad OFFLINE  

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Posted Mon Jan 2, 2017 4:01 PM

thank you for this....really liked this game back in the day.  although....haven't played it in years, so i now need to dig up the instructions (or walkthru) to figure out how to do it anymore!



#12 macdlsa OFFLINE  

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Posted Mon Jan 2, 2017 10:22 PM

 
The highest possible score is 20.25 steps, and the lowest possible score is one step. The complete scoring algorithm:

Spoiler

 

 

I already know all of the various hints (but that one, never used, though, of the secret exit in the guardian room) but the scoring chart is awesome !

Is it a thing that could be "seen" only with exploring the code or you (or someone else ?) wrote it by playing and try and re-try almost every possible situation ?
(I bet the first  ;) )

 

So, before that chart, the understanding of the score attribution could also be subjective... [pic]

RotlA_ArkFound+TopScore(steps).png

[ correct attribution is purple... ( ? )]

 

I'll try the latest Altirra soon and record a full-game to show you and so "deduce" if is the "top-score" or I could do better...



#13 phaeron OFFLINE  

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Posted Mon Jan 2, 2017 10:47 PM

 

I already know all of the various hints (but that one, never used, though, of the secret exit in the guardian room) but the scoring chart is awesome !

Is it a thing that could be "seen" only with exploring the code or you (or someone else ?) wrote it by playing and try and re-try almost every possible situation ?
(I bet the first  ;) )

 

Ha, no, I'm not that good. I didn't even know that you could enter the marketplace with the staff -- always blew the hole in the wall since they told you in the manual, and because frankly it was cool. A lot of it I uncovered when reversing the code, and then the rest when searching around the 'net for quirks and bugs that others had found to test. One of the last minute fixes I had to do was to the spider room, since I didn't know that Indy could move partially into the upper border there and had to put a workaround into the conversion code for it.

 

The scoring chart was determined from a routine in the code that computes your final score. The scoring items have been known and listed for years, but oddly everyone seems to get the Ark and shovel score bonuses swapped. BTW, there's apparently an issue with the extra lives scoring that I didn't notice -- apparently you always get at least +1 for your lives due to a code bug, so the lower bound is one point higher.

 

By 20.25 steps I mean 20 complete steps and a quarter of another step, where a step is four pixels tall. The game doesn't actually have a notion of steps -- it simply computes height, and everyone interprets it as steps because that's what you can see.



#14 macdlsa OFFLINE  

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Posted Tue Jan 3, 2017 9:47 AM

Sorry... I missed some things that you said in the "Scoring Chart"...

 

> Heh, never thought of that "hold-down-firebutton-to-set-the-ark-in-the-same-mesa" trick...

 

> The "hourglass" isn't unuseful, at all ! Just like the Ankh, it "carries" the same hook which could be used to travel through the mesa ! Some more care is needed, though : when you are in the "Mesa Field" do NOT scroll the selection dot on it if you don't need the hook, because as soon as you move the dot under it, the hook appears IMMEDIATELY, while with the Ankh is necessary to press the fire button. Also, the hourglass does not "teleport" Indy directly on the "Saucer Mesa" from anywhere in the game... it simply "release" the hook on the same mesa Indy is at that moment.

 

Well, in the clip above you can see my full-playthrough with highest score and both the easter eggs shown.

I played on Altirra rev2.81 and, yes, there's no more glitch in the entrance room  :thumbsup: .


 

 

 

Ha, no, I'm not that good. I didn't even know that you could enter the marketplace with the staff -- always blew the hole in the wall since they told you in the manual, and because frankly it was cool. A lot of it I uncovered when reversing the code, and then the rest when searching around the 'net for quirks and bugs that others had found to test. One of the last minute fixes I had to do was to the spider room, since I didn't know that Indy could move partially into the upper border there and had to put a workaround into the conversion code for it.

 

The scoring chart was determined from a routine in the code that computes your final score. The scoring items have been known and listed for years, but oddly everyone seems to get the Ark and shovel score bonuses swapped. BTW, there's apparently an issue with the extra lives scoring that I didn't notice -- apparently you always get at least +1 for your lives due to a code bug, so the lower bound is one point higher.

 

By 20.25 steps I mean 20 complete steps and a quarter of another step, where a step is four pixels tall. The game doesn't actually have a notion of steps -- it simply computes height, and everyone interprets it as steps because that's what you can see.

 

You mean enter in the "Temple Entrance" with the Amulet of Ra ?
Yep, it may be the only "secret" I've never discovered since a few years ago... I used to blew the wall with the granade (exactly, as the manual says...), too, so I obtained a maximum of 19.5 (or 19.75... ?!) steps.

 

Oh, the Spider Room's upper wall, yes... I never entered it anymore since it is almost unuseful for acquiring more points...

 

Extra lives scoring : interesting !

 

Heh... as I said in my prev. message, the understanding of the score attribution could be subjective, before your scoring chart, depending on "where" one could assume the single step is on the screen (see the "GREEN" and "BLUE" steps...), while the correct way to identificate a "step" is watching every 3pixels/lines "black hole" (purple in my prev. post picture) in the center of each section of the ladder...).



#15 phaeron OFFLINE  

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Posted Tue Jan 3, 2017 3:38 PM

> The "hourglass" isn't unuseful, at all ! Just like the Ankh, it "carries" the same hook which could be used to travel through the mesa ! Some more care is needed, though : when you are in the "Mesa Field" do NOT scroll the selection dot on it if you don't need the hook, because as soon as you move the dot under it, the hook appears IMMEDIATELY, while with the Ankh is necessary to press the fire button. Also, the hourglass does not "teleport" Indy directly on the "Saucer Mesa" from anywhere in the game... it simply "release" the hook on the same mesa Indy is at that moment.


That's the thing, there's nothing that the hourglass does that the Ankh doesn't do better. The Ankh can be activated anywhere to save time or save Indy, doesn't activate just by moving the cursor over it, and gives you a scoring bonus that the hourglass doesn't. You even get them in the same place.



#16 ZylonBane OFFLINE  

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Posted Tue Jan 3, 2017 11:19 PM

Just question . . is possible to convert Double Dragon or Kung-Fu Master or Frosty from A2600 too?

 

Two of those are arcade ports. Why would you ape the primitive 2600 versions instead of just making the best possible 8-bit version?



#17 Goochman OFFLINE  

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Posted Wed Jan 4, 2017 6:58 AM

Using Altirra has anyone else run into a problem moving between inventory?  Im using the keyboard "," and "." and unless I hold these keys down I dont get much movement.

 

Also - how do I buy a parachute?  I put the dot under a bag of gold, sit on the parachute and pressed the space bar.  The gold disappeared but I didnt get a parachute in my inventory.



#18 Poison OFFLINE  

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Posted Wed Jan 4, 2017 7:14 AM

 

Two of those are arcade ports. Why would you ape the primitive 2600 versions instead of just making the best possible 8-bit version?

 

It is very easy:) Full AAA 8bit game takes very much time. Like Rick Dangerous, Space Harrier and many others, many of them are not finished and may be will never be . . . This is game which looks very simple and may be easy for convert and I like theese three games, They are nice and good playable for me and Atari XL\XL have not any fighting game like theese two :)


Edited by Poison, Wed Jan 4, 2017 7:15 AM.


#19 macdlsa OFFLINE  

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Posted Wed Jan 4, 2017 9:20 AM

That's the thing, there's nothing that the hourglass does that the Ankh doesn't do better. The Ankh can be activated anywhere to save time or save Indy, doesn't activate just by moving the cursor over it, and gives you a scoring bonus that the hourglass doesn't. You even get them in the same place.

 

Well, I find "handy" having both Ankh and Hourglass with me because (as seen in the clip of my game) first I have to use the hook to go to the lower mesa and so enter in the map room; then, if I have the hourglass when I go out of the map room I have immediately available another hook which allow me to go to the right mesa, without forcing me to go back to the treasure room again...  ;)



#20 macdlsa OFFLINE  

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Posted Wed Jan 4, 2017 10:26 AM

Using Altirra has anyone else run into a problem moving between inventory?  Im using the keyboard "," and "." and unless I hold these keys down I dont get much movement.

 

Also - how do I buy a parachute?  I put the dot under a bag of gold, sit on the parachute and pressed the space bar.  The gold disappeared but I didnt get a parachute in my inventory.

 

Yep, I found the same "delay" with default keys, but I usually use an external USB joypad to move Indy, so I set Altirra in this way:
Input >>> Port1=Gamepad->Joystick(Port1) -:- Port2=ArrowKeys->Joystick(Port2)

[with this last setting you use arrow Left/Right and CTRL or SPACE to release the item... no "lag"  :thumbsup: , except of the "original delay" of the VCS controls, which is still known on this game]   
 

For the "parachute issue", you were probably in a wrong place, maybe even for few pixels... Indy has to be just under the White Sheik, aligned with him (look at the video of my game where I placed indy to catch the parachute  ;) ).



#21 Atari_Force OFFLINE  

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Posted Wed Jan 4, 2017 12:12 PM

phaeron, Is there a topic with all your previous A2600 ports?



#22 phaeron OFFLINE  

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Posted Wed Jan 4, 2017 2:38 PM

Using Altirra has anyone else run into a problem moving between inventory?  Im using the keyboard "," and "." and unless I hold these keys down I dont get much movement.

 

Also - how do I buy a parachute?  I put the dot under a bag of gold, sit on the parachute and pressed the space bar.  The gold disappeared but I didnt get a parachute in my inventory.

 

The game only allows the cursor to move every 8 frames, and those keys are just mirrored onto the player 2 movements, so yeah, you do need to hold them down a little bit. If you have upgraded from an old version of Altirra, you may still have the keyboard on cooked mode; changing it to raw mode in latest versions will give better response.

 

For buying any of the items from the sheiks in the markets, it is critical that Indy not be touching the sheik, or you'll get nothing.

 

phaeron, Is there a topic with all your previous A2600 ports?

 

http://atariage.com/...-for-atari-800/

http://atariage.com/...st-for-the-800/

http://atariage.com/...lone/?p=2913934

http://atariage.com/...8bit/?p=3310520



#23 devwebcl OFFLINE  

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Posted Thu Jan 5, 2017 5:49 AM

activision tennis, barnstorm, to mention some cool games from 2600.

#24 Drummerboy OFFLINE  

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Posted Thu Jan 5, 2017 8:18 PM

Amazing!!. 

 

Congratulations and thanks!. 

 

Just as suggest 2600 game names, could be nice ported to 8bit Computers: ET 2600; Robot Tank, Presure Cooker, Moon Patrol (i know we have a better version, but 2600 is nice), Kung Fu Master, Star Master,  Enduro (i know we have GACCRR, but could be funny Enduro 2600), California Games (To have even that version on Atari 8Bit Computers). 

 

Anyway, great job! 


Edited by Drummerboy, Thu Jan 5, 2017 8:31 PM.


#25 Philsan ONLINE  

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Posted Fri Jan 6, 2017 1:23 AM

Amazing!!. 

 

Congratulations and thanks!. 

 

Just as suggest 2600 game names, could be nice ported to 8bit Computers: ET 2600; Robot Tank, Presure Cooker, Moon Patrol (i know we have a better version, but 2600 is nice), Kung Fu Master, Star Master,  Enduro (i know we have GACCRR, but could be funny Enduro 2600), California Games (To have even that version on Atari 8Bit Computers). 

 

Anyway, great job! 

Would love ET, perhaps the fixed version.

Recently I found that a version for ZX Spectrum was made called E.T.X. There an interesting story about that game and the fact Atari did nothing to stop it on Retro Gamer Issue 162.






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