Re: Re: PET video to VGA

After a significative break on the subject, I finally managed to have a "perfect" display to my VGA LCD screen using a GB8220 and a simple 74LS02.

The secret is on R03 that needs to have it's 4 high bit at least =2 (vSync width) ... but not zero.

Knowing that, my setting for R00 to R09 on the 8032 at 50Kz/15.63Khz (measured at osciliscope) for text mode are (in decimal) : 63,40,53,33,33,7,25,32,0,8.

 

Regards - Hervé

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Message du : 19/12/2013 17:53
De : "Rob Clarke " <crock@clarke-family.org.uk>
A : cbm-hackers@musoftware.de
Copie à : 
Sujet : Re: PET video to VGA


 Here's my spreadsheet with all the timings from all common ROM's I could 
find plus the others that are on zimmers. You can use this to twiddle 
with the values and see the effect on the frequencies.

http://inchocks.co.uk/commodore/PET/PET_CRTC.xls

Anders is correct for the 80 column edit roms. For the 40 column ROM's 
the registers are at E7B1 and E7C3.

Rob

On 19/12/2013 13:21, Anders Carlsson wrote:
> Hervé wrote:
>
>> - What are registers values supposed to be OK ?
>
> Perhaps André:s site can help you?
> http://www.6502.org/users/andre/hwinfo/crtc/
> http://www.6502.org/users/andre/petindex/crtc.html
>
> It seems to that changing the register R2 would move the image to 
> either left or right. The second page has actual register values, see 
> the ones for CS/A65 as those were tuned for a 50 Hz TV. André also has 
> links to the composite video adapters and mentions that the CRTC 
> values need to be changed in order to get them to work.
>
>> - Locations, in this hacked ROM, to patch to change those registers 
>> values ?
>
> A quick hunt with the xpet monitor suggests $E72A (lower case?) and 
> $E73C (upper case/graphics?), but I'm not entirely sure.
>
> Best regards
>
> Anders Carlsson
>
>
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