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robinhedwards / UnoCart-2600

SD card multi-cart for the Atari 2600 (based on my UnoCart design)
GNU General Public License v3.0
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Support a psuedo-reset button #6

Open unwiredben opened 6 years ago

unwiredben commented 6 years ago

A feature that seems doable would be to have a pseudo-reset button on the board hooked up to a GPIO and pull-up resistor which would cause the firmware to start sending a series of BRK instructions until the button was released, upon which the cart would start serving the menu program. This would save wear-and-tear on the power switch on the console and allow switching games quicker.

DFL-git commented 6 years ago

Agree, a reset button will be great. The STM32 has an NRST line and maybe can be used to restart the main program. I'm not an expert on A2600, but if I understood, the unwiredben's post is to take care of the initial code vector, right?

unwiredben commented 6 years ago

Yes, it was a way to getting the currently running 6502 code on the 2600 back into a known state, although that might not be sufficient to act like a just powered-on 2600. Most games will init everything to the state they want, but I know some make assumptions about the state of RAM that wouldn't hold in this situation.