Re: [stella] Chip Select Line

Subject: Re: [stella] Chip Select Line
From: mickey_m@xxxxxxxxx
Date: Sun, 12 Jan 2003 00:56:57 +0000
The 7407 is an open-collector device.  It needs to be pulled high.  Do you do 
that?  I dont think timing is your issue, the 7407 is rated at 27ns max, it 
shouldnt skew the A12 enough to mess up setup times and stuff.  I know it 
sounds basic, but sometimes I miss them the most.  But then again, I am a 
programmer, so there is a good chance I dont know what I am talking about.

> Hello !
> I have made a little testing with an original PacMan ROM chip.
> I made all the lines available for measuring the signals. 
> If I connect all lines to the PacMan ROM, as in the original cartridge,
> everything works fine.
> What I did now is, that I connected the A12 line to an 7407 buffer and from the
> output of that buffer back to the CS line o the ROM. It is not inverting, so it
> should work. But it doesn't. Why not ?
> What are the timing requirements for the A12 line ? What am I missing ?
> It should work, shouldn't it ?
> Kroko.
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