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Scramble - 2600


johnnywc

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  • 9 months later...

I have a question regarding the detection of gamepads: virtvic built me a two button arcade stick. It works fine in all games as a one button stick. However in Scramble I can’t get the second button to work. He wired it up as button C according to the Sega pinout. But I guess something is still missing... any ideas? A regular Sega gamepad works fine. 

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25 minutes ago, root42 said:

I have a question regarding the detection of gamepads: virtvic built me a two button arcade stick. It works fine in all games as a one button stick. However in Scramble I can’t get the second button to work. He wired it up as button C according to the Sega pinout. But I guess something is still missing... any ideas? A regular Sega gamepad works fine. 

Hmmm, does it say "GAMEPAD FOUND" on startup?  If not, then the auto-dectection scheme probably isn't working for the arcade stick based on a different reading of pin 5 on startup.

 

Looking at the Scramble init code, it thinks you have a 2-button Sega Genesis controller connected if INPT1 (pin 5 on the Atari) is logical "high" on startup.  Can you reach out to virtvic to see how he has wired up pin 5?  If he grounded it (maybe he didn't need it), then unfortunately Scramble will think you have a 1-button joystick connected as this pin (and pin 9) are both 'low' when regular joysticks are connected.  

 

Hope this helps!

John

 

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Hi there! I just wired up button one to the normal fire button pin 6 on the atari 9 pin d plug and button 2 to pin 9 on the atari 9 pin d plug (would be button C on a megadrive).

 

I THINK THAT I SHOULD MAYBE HAVE WIRED THE SECOND BUTTON TO PIN 5?

 

I don't have a 2600 with a Harmony cart to test any 2 button games, but I checked the 2nd button (megadrive button C) on sonic the hedge hog (jumping ok with buttons 1 and 2) / Golden Axe (button 2 was jumping - I think?) and when I checked one of the Ninja Gaiden games, the 2nd button would alternate with jump and pause ('start' on a megadrive) ?

Edited by virtvic
Mistake in my text (2ND BUTTON PIN)
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38 minutes ago, virtvic said:

Hi there! I just wired up button one to the normal fire button pin 6 on the atari 9 pin d plug and button 2 to pin 9 on the atari 9 pin d plug (would be button C on a megadrive).

 

I THINK THAT I SHOULD MAYBE HAVE WIRED THE SECOND BUTTON TO PIN 5?

 

I don't have a 2600 with a Harmony cart to test any 2 button games, but I checked the 2nd button (megadrive button C) on sonic the hedge hog (jumping ok with buttons 1 and 2) / Golden Axe (button 2 was jumping - I think?) and when I checked one of the Ninja Gaiden games, the 2nd button would alternate with jump and pause ('start' on a megadrive) ?

You might be right. Pin 5 was probably the way to go. Well, live and learn... I will try it out one of these days. 

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41 minutes ago, root42 said:

@johnnywc thanks for the info. I guess I will have to wire pin 5 to GND then. I think virtvic used pin 6 & 9. Maybe I’ll even put in a throw switch to toggle pin 5. :) Thanks for looking up the autodetect code!

You're welcome!  :idea: I may be wrong, but I think you need to wire pin 5 to VCC (not GND) if you want the arcade stick to be recognized as a 2-button gamepad by Scramble since it's expecting INPT1 (paddle B) to be '1' on startup.  

 

Good luck!

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2 hours ago, johnnywc said:

You're welcome!  :idea: I may be wrong, but I think you need to wire pin 5 to VCC (not GND) if you want the arcade stick to be recognized as a 2-button gamepad by Scramble since it's expecting INPT1 (paddle B) to be '1' on startup.  

 

Good luck!

You need a pull up resistor on pin 9, and a reverse bias diode from pin 7 to pin 5 if you wanna use it wit sms as well. I got a schematic somewhere...

 

Yup. This one uses a toggle switch to select between sms and 7800 modes. Works on 7800, 2600 homebrew, and sms.

 

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Neat. I just want to use it on the Atari 2600. For the MegaDrive I have other controllers. 

 

So wiring pin 5 via a pullup resistor to VCC should do the trick? But which pin is VCC? In the pinouts (https://pinouts.ru/Game/sega_ms_joy_pinout.shtml) I can't see VCC...

 

EDIT: Found it: https://old.pinouts.ru/Inputs/JoystickAtari2600_pinout.shtml -- Seems pin 7 is VCC. So a ~500 Ohm from pin 5 to pin 7 should do the trick? And I guess pin 9 stays there for button 2?

Edited by root42
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2 hours ago, root42 said:

Neat. I just want to use it on the Atari 2600. For the MegaDrive I have other controllers. 

 

So wiring pin 5 via a pullup resistor to VCC should do the trick? But which pin is VCC? In the pinouts (https://pinouts.ru/Game/sega_ms_joy_pinout.shtml) I can't see VCC...

 

EDIT: Found it: https://old.pinouts.ru/Inputs/JoystickAtari2600_pinout.shtml -- Seems pin 7 is VCC. So a ~500 Ohm from pin 5 to pin 7 should do the trick? And I guess pin 9 stays there for button 2?

Pullup resistors (vcc pin 7) to pins 5 and 9. The value isn't critical (I used the same 560 ohm resistors I built my 7800 controllers with) but paddle pins need to be pulled high to work. Fire button to pin 6. Auxiliary button to pin 9.

 

If you have a Genesis controller and for whatever reason it spazes out on the Atari homebrews, a diode from pin 7 to pin 5 (plus end goes to pin 7, minus to 5) will peg pin 5 (genesis vcc) at 4.4v minimum ensuring proper function on the Atari, and will not impact operation on the genesis.

 

A diode instead of a pullup to pin 5 is not absolutely necessary but will ensure your two button homebrew joystick will function properly on the Sega Master System as well. A handful of master system games do not pull up pin 7, causing Genesis controllers to function incorrectly. You would need to cut pin 7 on the genesis controller, or install an inline toggle switch to play these titles.

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I’ve just wired a 2 button joystick to try this out, but I don’t have the 2600 game to check 2 button functionality. I wired it like this, and it seems to sort of work with a few megadrive games, but mainly, the 2nd button (button C on megadrive) alternates between button C and START, so some games will perform an action, then pause and so on? Am I presuming this is correct for what we need on 2600 games? 

 

0B1128CA-C6A9-4E15-8457-30F9E3D11759.jpeg

Edited by virtvic
phone spelling mistakes
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On 9/21/2019 at 11:30 AM, virtvic said:

I’ve just wired a 2 button joystick to try this out, but I don’t have the 2600 game to check 2 button functionality. I wired it like this, and it seems to sort of work with a few megadrive games, but mainly, the 2nd button (button C on megadrive) alternates between button C and START, so some games will perform an action, then pause and so on? Am I presuming this is correct for what we need on 2600 games? 

 

0B1128CA-C6A9-4E15-8457-30F9E3D11759.jpeg

Yeah that will work for homebrew.

 

However on the genesis, running second button to both start and C is going to spaz out a lot of games. Also if pin 7 gets pulled low by select, it might register as a button press on pin 9. This cause incompatibility issues in a handful of games using genesis controller on SMS.

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  • 5 months later...

I finally got around to modding the joystick. I used this document here:

 

http://www.bjars.com/hacks/CX40mod.pdf
 

I wired a 330Ω resistor between pin 7 and the side of the button that connects to pin 9. It won’t work with the Genesis now, But I don’t care about that, I‘ve got a couple of 8bitdo for that. 
 

I tried Scramble and it works beautifully. Finally I have two fire buttons. :)

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  • 1 month later...
  • 1 year later...

Ok, I'm a dweeb, but I can't for the life of me get past a section of level one. It's the level where you go through a tunnel and the only thing in the tunnel are fuel tanks. At one point, you are at the bottom of the screen and then have to go all the way up to the top to get to the next opening. I've tried many many times and just can't get to the top without crashing. I'm at slow speed and I start up to the opening immediately after leaving the bottom opening. Help!

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35 minutes ago, Big Doggy Dog said:

Ok, I'm a dweeb, but I can't for the life of me get past a section of level one. It's the level where you go through a tunnel and the only thing in the tunnel are fuel tanks. At one point, you are at the bottom of the screen and then have to go all the way up to the top to get to the next opening. I've tried many many times and just can't get to the top without crashing. I'm at slow speed and I start up to the opening immediately after leaving the bottom opening. Help!

Hi there!  I'm glad you're enjoying Scramble.  By your description, I believe you're on the 4th stage (the maze), correct?  The trick is not to go at slow speed but to approach the upcoming area at FAST speed (ship all the way to the right), then move diagonally up and to the left to make the turn to give you the maximum amount of time.  By going slow, you are minimizing your turn time instead of maximizing it. :idea:  

 

Hope that helps!

John

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58 minutes ago, Big Doggy Dog said:

Ok, I'm a dweeb, but I can't for the life of me get past a section of level one. It's the level where you go through a tunnel and the only thing in the tunnel are fuel tanks. At one point, you are at the bottom of the screen and then have to go all the way up to the top to get to the next opening. I've tried many many times and just can't get to the top without crashing. I'm at slow speed and I start up to the opening immediately after leaving the bottom opening. Help!

What I think helps to realize in Scramble is your ship can never move backwards in relation to something it "passed". i.e. once it passes something, you passed it for good.

 

So knowing that, when you're at that section you're describing: zip all the way to the right OF THE SCREEN as much as you can, and once that long vertical back wall in the maze is behind your ship, you can safely start pulling back, going up or down without worry. You should be able to make it to the top (or bottom) just in time to start zipping to the right of the screen again for the next section. :)

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