Re: 6561 (PAL VIC-I) interlace mode bit

From: Gerrit Heitsch <>
Date: Sun, 28 Aug 2011 13:39:58 +0200
Message-ID: <>
On 08/28/2011 12:11 AM, Segher Boessenkool wrote:
> (167MB, more complete;
> uploading a new one)

I'm looking at that one and am wondering about a few pad designations:

R/_W seems to be an 'input-only' pad since I cannot see any driver logic 
next to it. Does that mean that the VIC does not actively pull R/_W to 
high when accessing RAM? The circuit diagram for the 250469 board where 
this VIC was used shows a 3.3KOhm pullup for R/_W.

Then, below _CS and above LP I see 4 unlabeled pads which seem to have 
drivers associated to them but, according to the pinout don't seem to be 
used and they have a different form. The lines leading to them lead 
towards the video output logic. Testpads? Same for the pad below LP 
which suggests an input.

Then there is the pad between A5 and A6, it looks as if it was used but 
you didn't put a label on it and the VIC pinout doesn't show a pin 
between A5 and A6.

> All these have single signals labelled; I can do some more modest-
> sized jpegs with just the functional blocks labelled, if people like
> that?

That would be nice.


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Received on 2011-08-28 12:00:17

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