Re: 6567 revisions (was Re: 264/TED/Plus4 Story)

From: Marko Mäkelä <>
Date: Thu, 25 Aug 2011 20:02:15 +0300
Message-ID: <20110825170215.GB2692@x60s>
On Thu, Aug 25, 2011 at 06:13:03PM +0200, Gerrit Heitsch wrote:
>Hm, I own a 6569R3, some 6569R5 and some 8565R2. I don't notice any 
>difference in picture quality between the 6569-Revisions

Configure your screen to black-and-white, and you should notice that the 
6569R5 generates 9 luminance levels. Here is a simple test pattern:
Hit ctrl-9 to enter reverse mode, then hit ctrl-1, space, ctrl-2, space, 
..., ctrl-8, space, cbm-1, space, cbm-2, space, ..., cbm-8, space.

>the 8565R2 seems to provide a slighty brighter picture. It also has the 
>'grey-dots-bug'. If you write to the background or border color 
>register (even if this doesn't change the contents) you get a grey dot 
>on the screen at the moment the register is written to. The intro for 
>Giana Sisters does show that quite nicely. Looks like a kind of 'snow 
>effect' if done right. This doesn't happen on a 6569. On some 8565-VICs 
>it goes away once the chip warms up.
>The bug is also present with TED and the VIC used in the C128. It 
>seems as if it got introduced with the switch to HMOS.

Right, I can confirm this. I did not know that there was a HMOS VIC-II 
for the C64.

Hmm, now I got another question: What was the mysterious "always set 
this bit to 0" in the VIC-II? Was it used in some early 6567 revision? I 
do not remember any effect when I set it on any of the 6567 or 6569 that 
I had.

   D016       53270                 VIC Control Register
			    7-6    Unused
			    5      ALWAYS SET THIS BIT TO 0 !
			    4      Multi-Color Mode: 1 = Enable (Text or
			    3      Select 38/40 Column Text Display:
				     1 = 40 Cols
			    2-0    Smooth Scroll to X Pos

This is not to be confused with the C128 VIC-IIe test mode bit in $d02f 
or $d030 that really does something. This would not be the first bit 
that has been disabled in a Commodore video chip. In the NTSC VIC-I, 
there is a bit for enabling interlace mode. It does not work in the PAL 
VIC-I.  I wrote a test program for it: look for interlace.prg and 
interlace.tar.gz at

Best regards,


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Received on 2011-08-25 18:00:13

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