Re: 6502/6510 ROM selection daughterboard

From: Gerrit Heitsch <*gerrit_at_laosinh.s.bawue.de*> Date: Thu, 07 Jun 2012 12:45:46 +0200 Message-ID: <4FD0865A.9060902@laosinh.s.bawue.de> · gerrit_at_laosinh.s.bawue.de

On 06/06/2012 10:44 PM, silverdr@wfmh.org.pl 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.

Yes.

> 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.

  Gerrit

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