Jump to content

Photo

Flash ROM Cart


477 replies to this topic

#476 ralphb OFFLINE  

ralphb

    Dragonstomper

  • Topic Starter
  • 654 posts
  • Location:Germany

Posted Thu Mar 28, 2019 12:03 PM

Oh, now I see.  Yes, you need either jumper of resistor -- otherwise, the signal is missing from the bank switching circuit! 



#477 Ksarul OFFLINE  

Ksarul

    Quadrunner

  • 5,271 posts

Posted Fri Apr 5, 2019 10:32 AM

That resistor normally just keeps the cartridge reset circuit from being a dead short when cartridges are inserted into the console. It is such a low value to ensure it doesn't do much to interfere with the signal, but if it isn't present, you would need the shorting wire across the pads to ensure the reset circuit actually forces a reset.



#478 ralphb OFFLINE  

ralphb

    Dragonstomper

  • Topic Starter
  • 654 posts
  • Location:Germany

Posted Sat Apr 6, 2019 3:58 AM

Jim, that's true for the connection between RESET and -5V, but this resistor has a different purpose.
 
It's used for bank switching, and dates back to Atarisoft cartridges.  You can read all about it in this earlier post: http://atariage.com/...cart/?p=3549738
 
Back then there was an issue with incorrectly wired capacitor and resistor.  Besides the incorrect wiring, it also turned out that modern components are so fast that the FlashROM doesn't need resistor or capacitor.  But since you need to have something connecting the signal in the cart port to the 377 doing the switching, I just said keep the resistor.
 
EDIT: clarification

Edited by ralphb, Sat Apr 6, 2019 3:59 AM.





0 user(s) are browsing this forum

0 members, 0 guests, 0 anonymous users