Hardware Reset

[MiCV2]

Hi,

 

I'm missing a hardware reset on the GD7800 cartridge. Sometimes NTSC or A2600 programs hang and I have to turn off the A7800 console. A real reset button would protect the hardware. Can I do a real reset in the console (mainboard) that works 100%? Mainboard is PAL, Rev.3. Where on the mainboard could I attach the reset button, CPU?

 

Best regards 

[+-^CrossBow^-]

Not sure if this helps, but the Backbit pro has a reset to menu button on that doesn't use the normal console reset. Pretty sure all it does is ground pin 13 off the 4013 chip that handles the power on/off of the console. That is how it is on the NTSC 7800 anyway. The extra wire to have this features isn't required since most folks would just power the console on/off manually to switch games but it is an option that is there. So it might be possible to do something similar on the PAL consoles?

 

I will state that the reset function from the backbit cartridge working that way could be unique to the cartridge. There are also two dedicated reset pins on the 4013 that could be looked at also.

 

[+Stephen Moss]

18 hours ago, -^CrossBow^- said:

Pretty sure all it does is ground pin 13 off the 4013 chip that handles the power on/off of the console. That is how it is on the NTSC 7800 anyway.

Doesn't pin 1 handle the power On/Off & pin 13 is the reset line? It would make no sense to power off the console as that is not a reset and if you were gong to power off anyway then you may as well use the power switch.

Also pulling pin 13 directly to ground is a brute force way of doing it, if there is nothing to limit the current draw from the pin it will eventually fail so if it was me I would put a 1K resistor in the Reset line just after pin 13 and pull the side not connected directly to pin 13 down to ground.

18 hours ago, -^CrossBow^- said:

There are also two dedicated reset pins on the 4013 that could be looked at also.

Surely pulling the Reset (pin 4) of the 4013 high would power the console off, once off the only way of changing that would be to then be to...

1. Release the high in pin 4
2. Pull the Set pin (6) high, and then low to restore normal On/Off operation and then press the power button (seems a bit clumsy to me)

Also pulling the Reset (pin 10) high does nothing if Set is already high which it would be after power on thus you would need to manipulate both the Set & Reset pins of the 4013 as follows using a DPDT Switch momentary switch...

 

        Col 1          Col 2

Row 1   +5V            Gnd         Reset Condition (NO switch connections)

Row 2   R (pin 10)     S (pin 13)

Row 3   4013 Pin 2     C67/R48     Normal operation (NC switch connections)

 

 

[+-^CrossBow^-]

@Stephen Moss Guess I need to grammar better. When I stated Pin 13 from the 4013 and then said it controls the on/off status of the console, that was meant in generalizing what the 4013 IC is used for and not in stating what Pin 13 was used for. That is why that statement came after I named the 4013 IC?

 

The rest is just what I pulled up from looking at the pinouts on the 4013 and I was only providing some info to the OP on things to look at in more detail. 

 

Pin 13 is the pin used on the 4013 that an extra wire has to be attached to if someone with a BackBit Pro cartridge wants the reset back to menu to work. If they don't like that wire hanging out of their console, then a physical power on/off is required. I've not looked in detail, but I think that wire just attaches directly to a header pin soldered onto the adapter that goes to ground on the cartridge port. @evietron can provide more details on how she is accomplishing that since it is her design. I don't personally use the extra wire because again, I'm not a fan of the wire hanging out of my console exposed like that since it is the male connection end and thus exposed when not in use. For me I have the 7800 pretty much within arms reach anyway when playing it so powering the console off/on to reset back to the game menu selection isn't that big a deal to me.

 

But I appreciate the insight and detail Stephen! Should give more than enough info that @MiCV2 was looking for.

Edited Wednesday at 01:33 PM by -^CrossBow^-

[MiCV2]

Hello, the Atari 7800 is new for me. The GD7800 cartridge is a great addition. I just noticed that a real reset switch would be nice. If I start an a2600 game, I have no way of getting back into the menu. I always have to turn the console off and on again. That can't be good for the old chips. I'm surprised that no one has done that in their a7800, a small hidden hardware reset button 🤷‍♂️

[+-^CrossBow^-]

47 minutes ago, MiCV2 said:

Hello, the Atari 7800 is new for me. The GD7800 cartridge is a great addition. I just noticed that a real reset switch would be nice. If I start an a2600 game, I have no way of getting back into the menu. I always have to turn the console off and on again. That can't be good for the old chips. I'm surprised that no one has done that in their a7800, a small hidden hardware reset button 🤷‍♂️

Well the Backbit Pro cartridge does have a back to game menu reset on the cartridge. Not sure exactly how it works, but it does require a separate wire to be installed on the console and then attached onto the adapter board that the BBPro uses for the 7800. But, that adapter will play both 2600 and 7800 games and the reset to games menu does work on both. But again, I'm pretty sure it is just initiating a quick power off/on cycle on the console to do this.

 

Not sure on 2600 games, but the 7800GD does have an on screen menu you can pull up while playing games and there is an exit game option that will take you back to the game menu selection without having to power the console off/on? Does that not work when playing 2600 games? I honestly don't know since I only have 7800 games loaded up on my 7800GD.

 

[MiCV2]

13 minutes ago, -^CrossBow^- said:

Not sure on 2600 games, but the 7800GD does have an on screen menu you can pull up while playing games and there is an exit game option that will take you back to the game menu selection without having to power the console off/on? Does that not work when playing 2600 games? I honestly don't know since I only have 7800 games loaded up on my 7800GD.

Back to menu doesn't work with a2600 games.

Edited Wednesday at 04:20 PM by MiCV2