Re: 6502/6510 ROM selection daughterboard

From: Gerrit Heitsch <>
Date: Thu, 07 Jun 2012 12:45:46 +0200
Message-ID: <>
On 06/06/2012 10:44 PM, wrote:
> I would prefer a "universal" method that would apply to all boards. I
> take that CS on pin 21 is active HIGH and connected to +5 all the time
> but the other is active LOW and needs to be pulled up if not connected.


> Unless it is already pulled up somewhere on the board (rather than
> inside PLA - I have to check it), a pull-up resistor should be added.

The schematics don't list a pullup for the ROM _CS lines.

The only universal method that'll work on all boards is to de-solder the 
ROM, but not everyone can do that.


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Received on 2012-06-07 11:00:06

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