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Omega Race Arcade?


Jess Ragan

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Yes, it would.

 

(BTW - Haven't been able to configure either z26, StellaX or PCAEwin to read the relocated paddles, but it's fine on my Supercharger. Do the emulators only "activate" paddles for specific known games? Anyone know?)

 

Thanks for cranking that out!

 

Initially, I couldn't get it to work either (Stella for Mac). But then, I just started poking around the keyboard, and happened to hit the right arrow key and that started the game! It also fires the guns, so the emulation appears to be working, except you just can't steer. But it's getting closer! :D

 

(I tried modifying the stella.pro file, but to no avail.)

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However, I couldn't get it to work on the Mac version of Stella either. I modified the Tac/Scan entry of the Stella.pro file to see if that would do the trick, but nope. Perhaps there's just some key "weirdness" to Tac/Scan that isn't emulated?

 

There shouldn't be, reading the paddles is really straightforeward. However, it does overlap with the joystick (ie: Moving the joystick right is the same as pushing paddle0's button) so I _think_ the emulators only allow the paddle for pre-determined games.

 

Let me just check that I haven't got paddles disabled completely...

 

Yep, when I run Super Breakout, z26 automatically configures Left/Right arrow keys to the paddle. StellaX automatically maps the mouse to the paddle. Pcaewin, I can't get to function at all with the paddle.

 

But the hacked Tacscan, which should be identical does not work. I'm suspicious that the emu's are "fixed" to only recognised paddles on certain pre-determined games because there are other similar "cheats" - In Kool-Aid Man there's a bug in the code which causes most emulators to go bonkers (but works okay on many real machines). Except z26. z26 runs Kool-Aid man just fine. However, if you replicate the bug in a different program, z26 goes nuts too. So z26 isn't really dealing with the bug, it's just thinking "This is Kool-Aid Man, better skip that bug".

 

I think the emus are doing the same thing here, except with paddles...

 

Chris...

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However, I couldn't get it to work on the Mac version of Stella either. I modified the Tac/Scan entry of the Stella.pro file to see if that would do the trick, but nope. Perhaps there's just some key "weirdness" to Tac/Scan that isn't emulated?

 

Hmmm... shouldn't have edited that part of my post out. :roll: I need to do more testing before posting. Or less editing. I'm a notorious post-editor.

 

There shouldn't be, reading the paddles is really straightforeward. However, it does overlap with the joystick (ie: Moving the joystick right is the same as pushing paddle0's button) so I _think_ the emulators only allow the paddle for pre-determined games.

 

I thought the Stella.pro file used to affect this somehow. I used to have to have it present for some paddle games to work, at least the first time they were run.

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The emulators aren't "cheating" with the paddles. They emulate them just fine. You only have to "unplug" the default joysticks and "plug in" the paddles. ;) For known paddle games some emulator do that automatically, but for your onw creations you have to handle that manually.

 

In z26 you can use the -mX command line switch to select the the paddle to emulate with the mouse. -m1XY allows you to select two independent paddles for each of the mouse axis. The -kX switch selects the paddle to emulate with the keyboard, and -pX selects the sensitivity for this.

 

In Stella you have to create a new entry in the STELLA.PRO file for your game and specify the controller type for the left and right ports.

 

PCAE doesn't autodetect controllers. If you want to use anything besides the default joysticks, you have to enable the desired controller in the configuration menu.

 

With Kool Aid Man we are really cheating. The game uses an unusual sequence of early accesses to the positioning registers to place the score display. Emulating this properly would require to systematially try out all possible combinations of registers with write accesses at all possible times. Since this only seems to affect one game (OK, the Anteater screenshots indiate a similar problem, but there is no binary available to try it out) we decided to be lazy and cheat. But if anyone wants to do the nessessary experimentation to come up with a table of object displacements or even a universal formula for object positioning, we'll gladly update z26. ;)

 

 

Ciao, Eckhard Stolberg

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In z26 you can use the -mX command line switch to select the the paddle to emulate with the mouse. -m1XY allows you to select two independent paddles for each of the mouse axis. The -kX switch selects the paddle to emulate with the keyboard, and -pX selects the sensitivity for this.

 

Heh, thanks Eckhard! You'd think I'd know better by now since the last time I was whining about z26 it was also user error....

 

But if anyone wants to do the nessessary experimentation to come up with a table of object displacements or even a universal formula for object positioning, we'll gladly update z26.  ;)  

 

While I'm normally a sucker for "put up or..." even after this experimentation the result would still be "wrong".

 

According to the Stella documentation, modifying the HMxx registers within 24 cycles after an HMOVE is "unpredictable". And it truly is - it varies by machine.

 

While z26 "cheats" to run Kool-Aid Man "right", the other emus are actually "right" too because some consoles show the same behaviour. Originally it was thought only PAL 2600's exibited the bug while Kool-Aid Man was thought to run properly on NTSC 2600's. However, when I tried to use the bug as a NTSC/PAL autodetect, it turns out that many (all?) NTSC 2600Jrs exhibit the bug while some PAL 2600's do not.

 

My theory would be that Atari changed (fixed? Since the behaviour of later consoles is predicted by the emus and not exceptional as with earlier consoles) the TIA at some point (perhaps when the 7800 was introduced since the 7800 shows some other incompatabilities with the 2600?) and consoles from before that point run Kool-Aid Man properly and those after exhibit the bug.

 

 

Chris...

 

 

(Which also implies that exploiting the effects of changing HMxx illegally is a bad idea since it will behave diffently on different machines.)

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OK, first of all the big "HMOVE no-no" involves all object positioning registers, including RESPx and NUSIZx in some combinations. So not messing with all of those within the first 24 cycles after a HMOVE is a good advice to a programmer. But the object positions that result when you vialote this rule aren't really unpredictable. They are just different from normal.

 

Simple offences with changing only one positioning register work the same on all consoles. Quite a few games rely on these effects, like G.I. Joe or Double Dragon. John and I tried out all possible combinations and created a table for the misplacements. This table is now used in all three VCS emulators, and makes programming new games with them a lot easier, since there are less surprises when you fianlly try your code on a real VCS. ;)

 

The differences between the two types of VCS consoles only occur when you change more than one positioning register too close after a HMOVE. Affected by the Kool Aid Man positioning problem seem only some of the later 2600 Jrs. and some of the 7800. There are NTSC 7800s that play Kool Aid Man just fine, but all PAL 7800 don't. The PAL 7800 was released for Christmas of 1989, which might be the dividing line. But I haven't found a way to identify affected consoles without playing the game on it. It seems that there are more 2600 Jrs that are not affected than there are problematical ones, though. Therefore I think supporting Kool Aid Man should be the "right" behaviour in an emulator. (I know we are not properly doing it in z26 yet either.)

 

The mispositioning in the problematical 2600 Jrs. isn't unpredictable either. They all show the same off-positions for the score in Kool Aid Man, and it doesn't seem to be the same as in the emulators (including z26). So if an emulator author decides that this is the "right" behaviour for a 2600, then he should at least position the players "properly wrong". ;) This is where a new experimental table would come in handy, so no need to stop yourself from creating one, if you wanted to prove me that you could create it faster than me. You could always go and create positioning tables for both types of VCS consoles just to be on the safe side. ;)

 

 

Ciao, Eckhard Stolberg

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:D I got it to work! :D

 

Thanks to help from Voch (who maintains the stella.pro file), I added this entry to stella.pro:

 

"Cartridge.MD5" "9e5007131695621d06902ab3c960622a"

"Cartridge.Name" "Tac Scan (paddle hack) (1983) (Sega)"

"Cartridge.Manufacturer" "Sega"

"Cartridge.ModelNo" "001-01"

"Cartridge.Note" "Uses the Paddle Controllers"

"Cartridge.Rarity" "Uncommon"

"Cartridge.Type" "4K"

"Controller.Left" "Paddles"

"Controller.Right" "Paddles"

"Display.FrameRate" "60"

"Display.Height" "202"

"Display.Width" "152"

"Display.XStart" "8"

"Display.YStart" "44"

""

 

And presto - Tac/Scan now works in Stella! Where I'd gone wrong before, was I didn't have the correct checksum for the hacked version.

 

Thanks Christopher for making the hack!

 

tachack.gif

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Thanks to help from Voch (who maintains the stella.pro file), I added this entry to stella.pro

 

I've got it added to the Stella profile. I'm a bit confused as to whether it's "Tac-Scan" as suggested by this Atari 2600 box scan or "Tac/Scan" as suggested by the same box scan (see the copyright at the bottom of the second picture) and this KLOV entry. For now I'm using the dash because it's more file system friendly.

 

Voch

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Since this only seems to affect one game (OK, the Anteater screenshots indiate a similar problem, but there is no binary available to try it out) we decided to be lazy and cheat.

 

It seems most of the M-Network games use the same scoring display kernel (well, the same font style). What is it you see in the Anteater screen that would tip you off to a potential problem?

 

Btw, Thunderground also suffers from the same TIA incompatibility. Paul Slocum mentioned this a few months ago - http://www.atariage.com/forums/viewtopic.php?t=14625

 

One of the Z26 programmers must have been aware of it, since the score is shown properly with later versions. Does anyone know if any other games are affected by this??

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The mispositioning in the problematical 2600 Jrs. isn't unpredictable either. They all show the same off-positions for the score in Kool Aid Man, and it doesn't seem to be the same as in the emulators (including z26). So if an emulator author decides that this is the "right" behaviour for a 2600, then he should at least position the players "properly wrong".  ;)  This is where a new experimental table would come in handy, so no need to stop yourself from creating one, if you wanted to prove me that you could create it faster than me. You could always go and create positioning tables for both types of VCS consoles just to be on the safe side.  ;)  

 

 

Ciao, Eckhard Stolberg

 

Intentionally or otherwise, this thread has scared me out of EVER attempting to program something for Atari 2600. What a nightmare! :P

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i cant wait to see/play that ant eater game. I love the oils well style gameplay.

 

But on an unrelated note to the variance of the topic, can u guys talk about making a more arcade accurate 2600 omega race again, please :-) I love omega race! It's got to have the music as accurate as possible too. Vic-20 Omega Race is a great place to look for suggestions (as its raster also,), its my favorite home version of omega race ever.

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if u never knew u could use a paddle with it, you probably never played it. great 2600 shooter.

 

I have played it on an emulator. I got the cart at a flea market and never could get it to work--or so I thought. The cart takes about five or six tries to get it to load correctly. I just thought the 2600 wasn't reading it right.

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Well I know it's not nostalgia for me, as I've tried omega race in mame on several ocassions, and I still MUCH prefer the vic version. (It kills the weak c64 version too.) I only wish someone would figure out some way to take that game code and make it run full speed and flicker/slowdown-less on the higher levels. Some people ported it to the turbo graphic 16 on a pir8 multi cart filled with nothing but vic-20 games (no lie,) one of my fave tg16 carts of all time. Has mutant herd, omega race, radar rat race, seamus and many of my other vic-20 faves. The vic-20's games always really reminded me of 2600 games (In a good way,) but just a bit more buff....

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OK, first of all the big "HMOVE no-no" involves all object positioning registers, including RESPx and NUSIZx  

 

Ah! Now that explains some strangeness...

 

Simple offences with changing only one positioning register work the same on all consoles.  

 

Ah, okay. Good to know - Is there documentation available (ie: Is your table posted somewhere?)

 

The differences between the two types of VCS consoles only occur when you change more than one positioning register too close after a HMOVE.  

 

Ah, okay, that makes sense. My assumption, obviously, was that all such positionings showed the incompatibility problems.

 

You could always go and create positioning tables for both types of VCS consoles just to be on the safe side.  ;)  

 

Yeah, but since Kool-Aid Man (Thunderground? Anteater...) is about the only game affected by this, and presumably no new games are going to do this (at least on purpose) given the compatibility problems it introduces between the two flavours of consoles it's information of dubious value.

 

Thanks for all the info!

 

Chris....

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Intentionally or otherwise, this thread has scared me out of EVER attempting to program something for Atari 2600.  What a nightmare! :P

 

Please keep in mind that as far as 2600 technobable goes, this is pretty extreme/obscure/hardcore stuff...

 

"Bleeding edge" stuff on any console (or any skilled activity, really) usually gets pretty complicated, regardless (or else it wouldn't be "bleeding edge", would it?)...

 

Chris...

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I just want to mention that Chris Tumber programmed an Omega Race port for the Vectrex which is an update of the vector arcade version .. It is called Omega Chase and there is a version that supports the Atari Indy 500 driving controller (on the Vectrex!). Plus there is an option for two players at the same time. Omega Chase won best homebrew game of the year for 2001..

 

OC is a whip ass .. clean your clock kinda game ...

 

Rob Mitchell, Atlanta, GA

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Please keep in mind that as far as 2600 technobable goes, this is pretty extreme/obscure/hardcore stuff...

 

"Bleeding edge" stuff on any console (or any skilled activity, really) usually gets pretty complicated, regardless (or else it wouldn't be "bleeding edge", would it?)...

 

Chris...

 

I have a feeling this is a bleeding edge indeed. If I attempted to program a 2600 game using all those tricks and make it work right, I'd cut myself and let the blood run out. It would be much less painful! :(

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